Patent Publication Number: US-2021166584-A1

Title: Interactive education system for teaching patient care

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 15/223,795 (the “&#39;795 application), filed Jul. 29, 2016, the entire disclosure of which is hereby incorporated herein by reference in its entirety. 
     The &#39;795 application claims the benefit of the filing date of, and priority to, U.S. Provisional Patent Application No. 62/202,564, filed Aug. 7, 2015, which is hereby incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to interactive education systems for teaching patient care. In particular, the present disclosure relates to an interactive educational eye assembly including a set of animatronic eyes that resemble real-life human eyes, both in appearance and dynamics, to allow execution of medical tests for educational and diagnostic purposes. The disclosed interactive educational eye assembly may be referred to as a simulator or a multipurpose eye motion trainer. 
     BACKGROUND 
     It is desirable to train medical personnel and students in patient care protocols before allowing physical contact with real patients. Such training may involve training material such as textbooks and flashcards. However, textbooks and flash cards lack failed to provide the important benefits of hands-on practice to the students. On the other hand, allowing inexperienced students to perform medical procedures on actual patients that would allow for the hands-on practice cannot be considered a viable alternative because of the inherent risk to the patient. Because of these factors, patient care education has often been taught using medical instruments to perform patient care activity on a simulator, such as a manikin. A manikin is, for example, a life-sized anatomical human model used for educational and instructional purposes. 
     Existing simulators fail to exhibit accurate symptoms and to respond appropriately to student stimuli, thereby failing to provide realistic medical training to the students. Existing simulators also fail to look and feel lifelike, which fails to improve the training process. As such, there is a need to provide a simulator that overcomes the above deficiencies of existing stimulators. To that end, the present disclosure discloses an interactive education system for use in conducting patient care training sessions that is realistic and/or includes additional simulated features. 
     SUMMARY 
     The present disclosure provides interactive education systems, apparatus, components, and methods for teaching patient care. In various embodiments, a patient simulator may include a right eye including a right eyelid and a right pupil, and a left eye including a left eyelid and a left pupil, wherein the right pupil is configured to move within an area of the right eye and the left pupil is configured to move within an area of the left eye. The right pupil and the left pupil may move in a horizontal direction or a vertical direction or a combination of the horizontal direction and the vertical direction. The patient simulator may include at least one infrared (IR) transmitter to transmit IR radiation towards an object placed in front of the eye assembly, at least one IR sensor to receive an IR response signal reflected off the object, and a microprocessor to determine a location of the object based on the sensing of the IR response signal by the at least one IR sensor, and to effect movement of the right pupil and/or the left pupil based on the determined location of the object. The IR transmitter may transmit the IR radiation in a burst of frequency modulated pulses 
     In various embodiments, to effect movement of the right pupil and/or the left pupil, the microprocessor may compare a current position of the right pupil and/or the left pupil with the determined location of the object. The microprocessor may effect movement of the right pupil jointly with respect to the movement of the left pupil or may effect movement of the right pupil independently with respect to the movement of the left pupil. In various embodiments, the microprocessor may effect movement of the right pupil by a first displacement amount and to effect movement of the left pupil by a second displacement amount, the first displacement amount being different from the second displacement amount. 
     A method used in the patient simulator may include transmitting, via a first infrared (IR) transmitter, first IR radiation and transmitting, via a second infrared (IR) transmitter, second IR radiation towards an object placed in front of the simulator. The method may also include sensing, via a first IR sensor, a predetermined number of readings of first sensed data based on the first IR radiation being reflected off the object and sensing, via a second IR sensor, a predetermined number of readings of second sensed data based on the second IR radiation being reflected off the object. Further, the method may include averaging, via a microprocessor, the predetermined number of readings of the first sensed data to calculate average first sensed data and the predetermined number of readings of the second sensed data to calculate average second sensed data, and comparing the average first sensed data with the average second sensed data. Finally, the method may include determining a location of the object based on the comparing of the average first sensed data with the average second sensed data, and effecting movement of the right pupil and/or the left pupil based on a result of the comparing of the average first sensed data with the average second sensed data. 
     In various embodiments, the transmitting the first IR radiation and/or the transmitting the second IR radiation includes transmitting IR radiation in a burst of frequency modulated pulses. Also, the sensing may include recording a value corresponding to an intensity of the first and/or second IR radiation being reflected off the object. In various embodiments, the effecting movement of the right pupil and/or the left pupil includes effecting movement of the right and/or left pupil in a horizontal or a vertical direction, or a combination of horizontal and the vertical direction. The determining the location of the object may include determining that the location of the object is in front of the first IR sensor when the first average sensed data is greater than the second average sensed data, and the effecting movement of the right pupil and/or the left pupil may include orienting a position of the right pupil and/or the left pupil towards the determined location of the object in front of the first IR sensor. In various embodiments, the effecting movement of the right pupil and/or the left pupil may include effecting movement of the right pupil jointly or independently with respect to the movement of the left pupil. 
     A patient simulator may include a right eye assembly including a right pupil having a right iris and a left eye assembly including a left pupil having a left iris. A right optical sensor may sense a light condition associated with the right eye, and provide a right electrical signal based on the same, and a left optical sensor may sense a light condition associated with the left eye, and provide a left electrical signal based on the same. In various embodiments, a microprocessor may change a size of the right iris based on the right electrical signal, and change a size of the left iris based on the left electrical signal. The microprocessor may be electrically connected to the right optical sensor and to the left optical sensor, and may receive the right electrical signal and the left electrical signal. In various embodiments, the right optical sensor is placed within the right eye and the left optical sensor is placed within the left eye. 
     The microprocessor may change the size of the right iris by increasing or decreasing a circular size of the right iris, and may change the size of the left iris by increasing or decreasing a circular size of the left iris. In various embodiments, the microprocessor may increase or decrease the circular size of the right iris and/or the left iris within a diametric range of 1 mm to 8 mm. Also, the microprocessor may change the circular size of the right iris and/or the left iris to a default size, a totally constricted size, or a totally dilated size. The microprocessor may decrease the circular size of the right iris and/or the left iris to simulate constriction and may increase the circular size of the right iris and/or the left iris to simulate dilation. In various embodiments, the microprocessor may simulate constriction under bright light conditions and may simulate dilation under dark light conditions. The microprocessor may change a circular size of the right iris by electrically actuating a right size motor that is mechanically coupled to the right iris, and may change a circular size of the left iris by electrically actuating the left size motor that is mechanically coupled to the left iris. In various embodiments, a single motor may be used to implement the right size motor and the left size motor. 
     A method used in the patient simulator may include sensing, via a right optical sensor, a light condition associated with the right eye including a right pupil having a right iris, and sensing, via a left optical sensor, a light condition associated with the left eye including a left pupil having a left iris. The method may further include changing, via a microprocessor, a size of the right iris based on the right electrical signal and of the left iris based on the left electrical signal. The sensing the light condition associated with the right eye may include sensing the light condition associated with the right eye by the right optical sensor from within the right eye, and the sensing the light condition associated with the left eye may include sensing the light condition associated with the left eye by the left optical sensor from within the left eye. 
     The changing the size may include receiving, at the microprocessor, the right electrical signal from the right optical sensor and the left electrical signal from the left optical sensor. In various embodiments, the changing the size includes changing the size of the right iris by increasing or decreasing a circular size of the right iris, and changing the size of the left iris by increasing or decreasing a circular size of the left iris. The changing the size may further include increasing or decreasing the circular size of the right iris and/or the left iris within a diametric range of 1 mm to 8 mm. In various embodiments, the changing the size may include changing the circular size of the right iris and/or the left iris to a default size, a totally constricted size, or a totally dilated size. The changing the size includes simulating constriction under bright light conditions and to simulate dilation under dark light conditions. Further, the changing may include changing a circular size of the right iris by electrically actuating the right size motor that is mechanically coupled to the right iris, and changing a circular size of the left iris by electrically actuating the left size motor that is mechanically coupled to the left iris. 
     A patient simulator may include a right eye assembly including a right eyelid and a right pupil and a left eye assembly including a left eyelid and a left pupil. At least one blink motor may be coupled to the right eyelid and to the left eyelid, and a microprocessor may electrically actuate the at least one blink motor to rotate, wherein rotation of the at least one blink motor results in motion of the right eyelid and/or the left eyelid to simulate blinking. The patient simulator may further include a right eyelid position sensor that electrically reports a current position of the right eyelid, and a left eyelid position sensor that electrically reports a current position of the left eyelid. 
     The right eyelid and/or the left eyelid and may move between a closed position and an open position. The closed position maybe the default position. In various embodiments, the motion of the right eyelid is independent from the motion of the left eyelid. The microprocessor may continuously monitor positions of the right eyelid using the right eyelid position sensor and of the left eyelid using the left eyelid position sensor. In various embodiments, the microprocessor may actuate rotation of the at least one blink motor in a first direction to effect closing of the right eyelid and the left eyelid, and may actuate rotation of the at least one blink motor in a second direction to effect opening of the right eyelid and the left eyelid. The microprocessor may actuate rotation of the motor in the second direction when right eyelid or the left eyelid is in the closed position. The microprocessor may control a speed of motion of the right eyelid and/or the left eyelid, and may control a speed of rotation of the at least one blink motor to control a rate of blinking of the right eyelid and/or the left eyelid. 
     A method for using the patent simulator may include mechanically coupling at least one blink motor to a right eyelid of a right eye and to a left eyelid of the left eye, and electrically actuating, via a microprocessor, the at least one blink motor to rotate, wherein rotation of the at least one blink motor results in motion of the right eyelid and/or the left eyelid to simulate blinking. The electrically actuating may include receiving electrical signals associated with a current position of the right eyelid from a right eyelid position sensor, and receiving electrical signals associated with a current position of the left eyelid from a left eyelid position sensor. The motion of the right eyelid and/or the left eyelid may include motion between a closed position and an open position. The electrically actuating may also include continuously monitoring positions of the right eyelid using the right eyelid position sensor and of the left eyelid using the left eyelid position sensor. 
     In various embodiments, the electrically actuating may include actuating rotation of the at least one blink motor in a first direction to effect closing of the right eyelid and the left eyelid, and actuating rotation of the at least one blink motor in a second direction to effect opening of the right eyelid and the left eyelid. The electrically actuating may include actuating rotation of the motor in the second direction when the right eyelid or the left eyelid is in the closed position. Finally, the electrically actuating may include controlling a speed of rotation of the at least one blink motor to control a speed of motion of the right eyelid and/or the left eyelid, and controlling a speed of rotation of the at least one blink motor to control a rate of blinking of the right eyelid and/or the left eyelid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present disclosure will become apparent in the following detailed description of illustrative embodiments with reference to the accompanying of drawings, of which: 
         FIG. 1  illustrates an exemplary schematic block diagram  100  of the simulator according to various embodiments of the present disclosure. 
         FIG. 2  illustrates a simulator  200  including the exemplary multipurpose eye motion trainer according to various embodiments of the present disclosure. 
         FIG. 3A  illustrates a plan view of an exemplary range of horizontal movement for the right and left pupils according to various embodiments of the present disclosure. 
         FIG. 3B  illustrates a plan view of another exemplary range of horizontal movement for the right and left pupils according to various embodiments of the present disclosure. 
         FIG. 4  illustrates an exemplary method  400  for performing simulation of horizontal movements in the joint tracking mode according to various embodiments of the present disclosure. 
         FIG. 5  illustrates an exemplary method  500  for performing simulation of horizontal movements in the independent tracking mode according to various embodiments of the present disclosure. 
         FIGS. 6A-6F  illustrate exemplary positions of the right and left pupils according to various embodiments of the present disclosure. 
         FIG. 7  illustrates a simulator  700  including the exemplary multipurpose eye motion trainer according to various embodiments of the present disclosure. 
         FIGS. 8A-8C  illustrate an exemplary range of vertical movement for the right and left pupils according to various embodiments of the present disclosure. 
         FIG. 9  illustrates an exemplary method  900  for performing simulation of vertical movements in the joint tracking mode according to various embodiments of the present disclosure. 
         FIG. 10  illustrates an exemplary method  1000  for performing simulation of vertical movements in the independent tracking mode according to various embodiments of the present disclosure. 
         FIG. 11A  illustrates an electro-mechanical block diagram  1100  of the simulator according to various embodiments of the present disclosure. 
         FIG. 11B  illustrates an exemplary front view of an eye of the simulator according to various embodiments of the present disclosure. 
         FIGS. 12A-12C  illustrate exemplary changes in the size of the iris according to various embodiments of the present disclosure. 
         FIG. 13  illustrates an exemplary method  1300  for performing simulation of pupillary changes according to various embodiments of the present disclosure. 
         FIG. 14  illustrates an electro-mechanical block diagram  1400  of the simulator according to various embodiments of the present disclosure. 
         FIG. 15  illustrates an exemplary mechanism  1500  used for horizontal movement of a pupil (right or left) according to various embodiments of the present disclosure. 
         FIGS. 16A-B  illustrate exemplary mechanisms  1600  used for vertical movement of a pupil (right or left) according to various embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is intended. Any alterations and further modifications in the described devices, instruments, methods, and any further application of the principles of the disclosure as described herein are contemplated as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and/or steps described with respect to one embodiment may be combined with the features, components, and/or steps described with respect to other embodiments of the present disclosure. 
     As discussed above, the present disclosure discloses an interactive educational system for use in conducting patient care training sessions that is realistic and/or includes additional simulated features. In various embodiments, the presently disclosed simulator or multipurpose eye motion trainer realistically replicates the motion of a human eye in response to user stimuli in a way that is useful for medical educational and diagnostic purposes. The multipurpose eye motion trainer includes novel eye movement and eye tracking features. These features are critical because eye movement conveys important health information regarding the patient. For example, impaired eye movement may indicate that the patient has suffered from or is at risk of suffering from a stroke and/or brain/muscle damage. 
     In various embodiments, the presently disclosed simulator or multipurpose eye motion trainer may replicate performance of an “accommodation test,” which is used to examine any impairment in the eyes of a patient. During the “accommodation test,” a doctor instructs the patient to view an object, and to track horizontal and vertical movements of the object with the patient&#39;s eyes (without moving their head). If the patient is unable to follow the object with both eyes, such that, for example, one eye lags behind another during the tracking, then this impaired eye movement indicates that the patient has a motor impairment with respect to the eyes, which often results due to having suffered a stroke and/or brain damage. In this way, the presently disclosed multipurpose eye motion trainer serves as an educational and diagnostic simulator by simulating eye movement and eye tracking. However, existing simulators do not include the novel eye movement or eye tracking features. As such, the existing simulators fail to provide realistic educational or diagnostic training to the students. 
     Simulation of Movement:  FIG. 1  illustrates an exemplary schematic block diagram  100  of the simulator according to various embodiments of the present disclosure. The simulator (see  FIG. 2 ) may be a manikin in the form of a human face, and may include an eye assembly. The eye assembly may include a right eye assembly  101  of the simulator, a left eye assembly  105  of the simulator, and associated circuitry to control functions to be performed by the right and left eyes  101 ,  105 . The right eye assembly  101  may include a right pupil  102  and a right eyelid  103 . The left eye assembly  105  may include a left pupil  106  and a left eyelid  107 . The simulator may include a microcontroller  110 , one or more IR sensors  120 , one or more IR transmitters  130 , an electronic memory  180 , and an input/output interface  190 . As discussed in further detail below, for simulating horizontal movement, the simulator may include a right pupil position sensor  140 , a right pupil motor  150 , a left pupil position sensor  160 , a left pupil motor  170 . Similarly, for simulating vertical movement, the simulator may include a right pupil position sensor  240 , a right pupil motor  250 , a left pupil position sensor  260 , a left pupil motor  270 . The separate right and left motors  150 ,  170  allow independent control of horizontal movement of the right and left pupils  102 ,  106 , respectively. Similarly, the separate right and left motors  250 ,  270  allow independent control of vertical movement of the right and left pupils  102 ,  106 , respectively. The independent control of the pupils is relevant because it allows medical tests to be performed individually on each eye. The right and left pupil position sensors  140 ,  160 ,  240 ,  260  may be rotary position sensors that sense rotational positions of the right and left pupils  102 ,  106  respectively. 
     The microcontroller  110  may include an integrated circuit (e.g., ASIC) and may be programmed with appropriate software to allow the simulated eye tracking and eye movements of the right and left pupils  102 ,  106 . The input/output interface  190  may include peripheral input devices like a keyboard, mouse and joystick, and output devices such as a display, speakers, and a printer. The microcontroller  110  may exchange information with connected components (internal and external) by using a Universal Serial Bus (USB), a one-wire RS-232 communication interface, or a I2C communication interface. 
     The microcontroller  110  may be electrically connected to the one or more IR transmitters  130 , and controls operations of the one or more IR transmitters  130 . For example, the microcontroller  110  controls radiation of the IR radiation from each of the IR transmitters  130 . Also, the microcontroller  110  is electrically connected to the one or more IR sensors  120 , and controls operation of the one or more IR sensors  120 . For example, the microcontroller  110  controls sensing of reflected IR response signals by the one or more IR sensors  120 . That is, to simulate eye tracking and eye movement, the microcontroller  110  instructs at least one IR transmitter  130  to transmit IR radiation and instructs at least one IR sensor  120  to sense IR response signals reflected off the object. The microcontroller  110  may store the sensed IR response signals by the at least one IR sensor  120  in the electronic memory  180 . Based on the IR response of the sensed IR response signals, the microcontroller  110  decodes the presence and location of the object. In various embodiments, the sensing of the IR response signals may include sensing an intensity of the reflected IR response signals, and recording a (digital) value corresponding to the sensed intensity of the IR response signals. The microcontroller  110  may compare the recorded values, and may determine that the object is placed closest to the sensor that records the greatest value. That is, the microcontroller  110  may determine that the object is placed closest to the sensor that senses IR response signals having the highest intensity. When two IR sensors measure substantially equal IR responses, the microcontroller  110  may determine that the object is placed in between the two IR sensors. For example, the microcontroller  110  may calculate a difference between two different values recorded by two different IR sensors, and may determine that the object is placed between the two different IR sensors when the calculated difference is less than a predetermined threshold value. In various embodiments, the IR response may have to be equal to or greater than a predetermined threshold IR response value for the at least one IR sensor to sense the IR response signal. 
     Once the microcontroller  110  has decoded the location of the object with respect to the known locations of the IR sensors  120 , the microcontroller  110  may instruct the right pupil position sensor  140  to report a current position of a right pupil  102  within the right eye  101 . Similarly, the microcontroller  110  may instruct the left pupil position sensor  160  to report a current position of the left pupil  106  within the left eye  105 . The microcontroller  110  may then independently compare the current positions of the right and left pupils  102 ,  106  with respect to the decoded location of the object, and determine whether the current positions of the right and left pupils  102 ,  106  correspond to the decoded location of the object. For example, to determine whether the current positions of the right and left pupils  102 ,  106  correspond to the decoded location of the object, the microcontroller  110  may determine whether the current positions of the right and left pupils  102 ,  106  are oriented towards the decoded location of the object. 
     The microcontroller  110  may determine to effect no change in the current positions of the right and left pupils  102 ,  106  when it is determined that the current positions of both the right and left pupils  102 ,  106  correspond to the decoded location of the object. However, the microcontroller  110  may instruct the right pupil motor  150  to change the current position of the right pupil  102  when it is determined that the current position of the right pupil  102  does not correspond to the decoded location of the object. For example, the microcontroller  110  may instruct the right pupil motor  150  to position the right pupil  102  such that the right pupil  102  is oriented (i.e., looking) towards the decoded location of the object. Similarly, the microcontroller  110  may instruct the left pupil motor  170  to change the current position of the left pupil  106  when it is determined that the current position of the left pupil  106  does not correspond to the decoded location of the object. For example, the microcontroller  110  may instruct the left pupil motor  170  to position the left pupil  106  such that the left pupil  106  is oriented (i.e., looking) towards the decoded location of the object. 
     In various embodiments, the microcontroller  110  may change the positions of the right and left pupils  102 ,  106  in the horizontal direction, the vertical direction, and in a combination of horizontal and vertical directions. The ability of the simulator to effect changes in the positions of the right and left pupils  102 ,  106  in all of the above directions allows the simulator to realistically simulate various medical tests performed by doctors on human eyes. Further, the microcontroller  110  may change the current position of the right pupil  102  independently from the current position of the left pupil  106 . Further, the microcontroller  110  may change the current position of the right pupil  102  by an amount of displacement that is lower than, equal to, or greater than a displacement of the left pupil  106 , and vice versa. 
     Horizontal Movement: Simulation of horizontal movement of the right and left pupils  102 ,  106  in accordance with placement and movement of an object (e.g., pencil, finger, etc.) will now be described. Simulating horizontal movement includes placing the object at an eye-level in front of the simulator and moving the object in a horizontal plane that is parallel to the horizontal plane that includes the left and right eyes  101 ,  105 . The right and left eyes  101 ,  105  are sized, shaped, and colored to simulate natural human eyes. The simulator senses the presence and the movement of the object using the three IR sensors  120 ,  121 ,  122  and the four IR transmitters  130 ,  131 ,  132 ,  133 , and allows for corresponding horizontal movements of the right and left pupils  102 ,  106 . In various embodiments, the horizontal movement of the right and left pupils  102 ,  106  may be controlled such that the right and left pupils  102 ,  106  move together. Alternatively, in various embodiments, the horizontal movement of the right pupil  102  is controlled independently from the horizontal movement of the left pupil  106 . Further, the amount of horizontal displacement of the right pupil  102  may be same or different with respect to the amount of horizontal displacement of the left pupil  106 . 
       FIG. 2  illustrates a simulator  200  including the exemplary multipurpose eye motion trainer according to various embodiments of the present disclosure. The simulator  200  may be a manikin in the form of a human face, and may include an eye assembly. The eye assembly may include the above discussed right and left eyes  101 ,  105 , and associated circuitry to control functions to be performed by the right and left pupils  102 ,  106 . The right eye  101  may include a right eyelid  103 , and the left eye  105  may include a left eyelid  107 . The associated circuitry for simulation of horizontal movement may include three infrared (IR) sensors  120 ,  121 ,  122  and four infrared (IR) transmitters  130 ,  131 ,  132 ,  133  that are electrically controlled by the microcontroller  110 . The IR sensors and the IR transmitters may be placed under silicone skin (with special openings) of the simulator  200 . This allows the simulator  200  to appear more lifelike. 
     In various embodiments, the IR sensors  120 ,  121 ,  122  may be placed in a forehead section of the simulator  200  in close proximity to the eyes  101 ,  105 . For example, as shown in  FIG. 2 , the IR sensors  120 ,  121 ,  122  may be placed in a horizontal plane above the horizontal plane that includes the right and left eyes  101 ,  105 . However, in various embodiments, the IR sensors  120 ,  121 ,  122  may be placed in different horizontal planes as long as they allow the functions to be performed by the eye assembly discussed in the present disclosure. Also, the IR transmitters  130 ,  131 ,  132 ,  133  may be placed in a horizontal plane in close proximity to the right and left eyes  101 ,  105 . For example, as shown in  FIG. 2 , the IR transmitters  130 ,  131 ,  132 ,  133  may be placed in a horizontal plane near the horizontal plane that includes the right and left eyes  101 ,  105 . However, in various embodiments, the IR transmitters  130 ,  131 ,  132 ,  133  may be placed in different horizontal planes as long as they allow the functions to be performed by the eye assembly discussed in the present disclosure. In various embodiments, the eye movement and/or eye tracking is simulated using the IR sensors  120 ,  121 ,  122  and the IR transmitters  130 ,  131 ,  132 ,  133 . 
     One or more of the three IR sensors  120 ,  121 ,  122  may be coupled to sensing IR response signals originating from one or more of the four IR transmitters  130 ,  131 ,  132 ,  133  to form respective sensor-transmitter pairs. For example, in the present embodiment for horizontal movement, the IR sensor  120  may be configured to sense IR response signals resulting from IR transmissions from the IR transmitter  130 , the IR sensor  121  may be configured to sense IR response signals resulting from IR transmission from two IR transmitters  131 ,  132 , and the IR sensor  122  may be configured to sense IR response signals resulting from IR transmissions from the IR transmitter  132 . In various embodiments, the two IR transmitters  131 ,  132  may be connected in series and may operate together such that the two IR transmitters  131 ,  132  are turned on and off at the same time. An IR sensor may be coupled to an IR transmitter by tuning the sensing frequency of the IR sensor to the transmitting modulated frequency of the IR transmitter and/or by positioning the IR sensor in close proximity to the IR transmitter. The tuning of the sensing frequency to the transmitting modulated frequency results in the IR sensor being isolated from environmental conditions so as to allow accurate sensing of the IR response signal. 
       FIG. 3A  illustrates a plan view of an exemplary range of horizontal movement for the right and left pupils  102 ,  106  according to various embodiments of the present disclosure. The right and the left pupils  102 ,  106  may be identical, but maybe controlled independently from each other with respect to movement (e.g., horizontal, vertical, etc.). The exemplary range of horizontal motion may be 60° with the center being at 30°, as shown  FIG. 3A . That is, each pupil  102 ,  106  may be centered at the default position of 30°, and may be rotated to the left of the default position by 30° (to the 60° position) and to the right of the default position by 30° (to the 0° position).  FIG. 3A  shows the 30° position as the default position of the right and left pupils  102 ,  106 . In the default position, the right and left pupils  102 ,  106  may be placed in the center of the right and left eyes  101 ,  105 , respectively, to simulate a person looking substantially straight ahead.  FIG. 3A  also shows a position of the right and left pupils  102 ,  106  rotated to the right of the default position by 15° (the 15° position). This position simulates a person slightly looking to the right. Further,  FIG. 3A  shows a position of the right and left pupils  102 ,  106  rotated to the right of the default position by 30° (the 0° position). This position simulates a person looking further to the right.  FIG. 3A  shows a position of the right and left pupils  102 ,  106  rotated to the left of the default position by 15° (the 45° position). This position simulates a person slightly looking to the left. Finally,  FIG. 3A  shows a position of the right and left pupils  102 ,  106  rotated to the left of the default position by 30° (the 60° position). This position simulates a person looking further to the left. 
       FIG. 3B  illustrates a plan view of another exemplary range of horizontal movement for the right and left pupils  102 ,  106  according to various embodiments of the present disclosure. In various embodiments, the total range of horizontal movement may be divided into zones. For example, as shown in  FIG. 3B , the range of horizontal movement may be divided into three equal zones. The three equal zones may be, for example, a right view zone, a central view zone, and a left view zone. In the default position, the right and left pupils  102 ,  106  may be placed in the central view zone of the right and left eyes  101 ,  105 , respectively, to simulate a person looking substantially straight ahead. The right and left pupils  102 ,  106  may be placed in the right view zone of the right and left eyes  101 ,  105 , respectively, to simulate a person looking substantially to the right. Finally, the right and left pupils  102 ,  106  may be placed in the left view zone of the right and left eyes  101 ,  105 , respectively, to simulate a person looking substantially to the left. 
     The simulation of horizontal movement of the right and left pupils  102 ,  106  may be conducted in two modes—the joint tracking mode or the independent tracking mode. In the joint tracking mode, both the right and the left pupils  102 ,  106  may be controlled together such that the right and left pupils  102 ,  106  are displaced jointly in the same direction. Alternatively, in the independent tracking mode, the right pupil  102  may be controlled independently with respect to the left pupil  106  such that the right pupil  102  may move with a different amount of displacement with respect to the left pupil  106 . For example, when an object is placed to the left of the simulator  200 , the left pupil  106  may be rotated to the left of its default position by 15° (to the 45° position) and the right pupil  102  may be rotated to the left of its default position by 30° (to the 60° position). In addition, in the independent tracking mode, the right pupil  102  may move in a different direction with respect to the left pupil  106 . For example, two objects may be placed in front of the simulator  200 , such that a first object is in front of the IR sensor  120  and a second object is in front of the IR sensor  122 . In this case, the right pupil  102  may be rotated to the right of its default position by 15° (to the 15° position) or by 30° (to the 0° position) to be oriented (i.e., looking) towards the object in front of the IR sensor  120 , and the left pupil  106  may be rotated to the left of its default position by 15 (to the 45° position) or 30° (to the 60° position) to be oriented (i.e., looking) towards the object in front of the IR sensor  122 . 
       FIG. 4  illustrates an exemplary method  400  for performing simulation of horizontal movements in the joint tracking mode according to various embodiments of the present disclosure. The method starts at step  401 . At step  402 , the microcontroller  110  places both the right and left pupils  102 ,  106  in the default positions such that both eyes appear to be looking substantially straight ahead. For example, the microcontroller  110  may instruct the right pupil motor  150  to place the right pupil  102  in its default position at 30° and may instruct the left pupil motor  170  to place the left pupil  106  in its default position at 30°. At this time, an object (e.g., finger, pencil, etc.) may be placed at eye-level in front of the simulator. 
     At step  403 , the microcontroller  110  turns on the first coupled sensor-transmitter pair of the IR sensor  120  and the IR transmitter  130 . In various embodiments, when the first coupled sensor-transmitter pair is turned on, the IR transmitter  130  may transmit a burst of frequency modulated IR radiations. The burst may include 100 pulses, each pulse having a period of about 2 μs and a duty cycle of 50%. The transmitted pulses of IR radiations may reflect off the surface of the object in front of the simulator and the resulting IR response signals are sensed by the IR sensor  120 . As previously discussed, the IR sensor  120  may sense the IR response signals and record a value corresponding to the sensed intensity of the reflected IR response signals. At this time, the first coupled sensor-transmitter pair of the IR sensor  120  and the IR transmitter  130  may be turned off. 
     At step  404 , the microprocessor  110  stores the IR response data sensed by the IR sensor  120  in the electronic memory  180  as a reading of first sensed data. 
     At step  405 , the microcontroller  110  turns on the second coupled sensor-transmitter pair of the IR sensor  121  and IR transmitters  131 ,  132  connected in series. In various embodiments, when the second coupled sensor-transmitter pair is turned on, the IR transmitters  131 ,  132  may transmit bursts of frequency modulated IR radiations. The burst may include 100 pulses, each pulse having a period of about 2 μs and a duty cycle of 50%. The transmitted pulses of IR radiations may reflect off the surface of the object in front of the simulator and the resulting IR response signals are sensed by the IR sensor  121 . As previously discussed, the IR sensor  121  may sense the IR response signals and record a value corresponding to the sensed intensity of the reflected IR response signals. At this time, the second coupled sensor-transmitter pair of the IR sensor  121  and the IR transmitters  131 ,  132  may be turned off. 
     At step  406 , the microprocessor  110  stores the IR response data sensed by the IR sensor  121  in the electronic memory  180  as a reading of second sensed data. 
     At step  407 , the microcontroller  110  turns on the third coupled sensor-transmitter pair of the IR sensor  122  and the IR transmitter  133 . In various embodiments, when the third coupled sensor-transmitter pair is turned on, the IR transmitter  133  may transmit a burst of frequency modulated IR radiations. The burst may include 100 pulses, each pulse having a period of about 2 μs and a duty cycle of 50%. The transmitted pulses of IR radiations may reflect off the surface of the object in front of the simulator and the resulting IR response signals are sensed by the IR sensor  122 . As previously discussed, the IR sensor  122  may sense the IR response signals and record a value corresponding to the sensed intensity of the reflected IR response signals. At this time, the third coupled sensor-transmitter pair of the IR sensor  122  and the IR transmitter  133  may be turned off. 
     At step  408 , the microprocessor  110  stores the IR response data sensed by the IR sensor  122  in the electronic memory  180  as a reading of third sensed data. 
     At step  409 , once all the sensor-transmitter pairs have been cycled through and sensed data from all the IR sensors has been recorded, the microprocessor  110  increments a counter having an initial value of zero. That is, at step  409 , the microprocessor  110  increments the counter to have a value of 1. This signifies that one cycle of collecting and recording data from all the IR sensors has been completed. 
     At step  410 , the microprocessor  110  determines whether the counter value is equal to a predetermined value. This predetermined value may be a predetermined number of cycles for collecting and recording data from all the IR sensors after which the microprocessor  110  processes the recorded data to determine the location of the object and to effect movement of the right and left pupils  102 ,  106  to correspond to the determine location of the object. In the present embodiment, the predetermined value is set to 5. That is, the data is collected and recorded from all the IR sensors for five cycles after which the microprocessor  110  processes the recorded data to determine the location of the object and to effect corresponding movement of the right and left pupils  102 ,  106 . However, any integer value greater than zero may be used as the predetermined value. 
     If the microprocessor  110  determines that the counter value is not equal to the predetermined value, then the method moves to step  403 . Alternatively, if the microprocessor  110  determines that the counter value is equal to the predetermined value, the method moves to step  411 . At this point, the microprocessor  110  has determined that five cycles of collecting and recording data from all the IR sensors has been completed. 
     At step  411 , the microprocessor  110  resets the counter such that the counter value is equal to zero. 
     At step  412 , the microprocessor  110  averages the five readings of the first sensed data and records the results as average first sensed data, averages the three readings of the second sensed data and records the result as average second sensed data, and averages the three readings of the third sensed data and records the result as average third sense data. 
     At step  413 , the microprocessor  110  compares the values of the average first sensed data, the average second sensed data, and the average third sensed data. Based on the comparison, the microprocessor  110  determines which average sensed data has the highest value. 
     At step  414 , the microprocessor  110  determines the location of the object to be in front of the IR sensor associated with the average sensed data having the highest value. For example, if at step  413 , the microprocessor  110  determines that the first average sensed data has the highest value, then the microprocessor  110  determines that the location of the object is in front of the IR sensor  120 . Similarly, if at step  413 , the microprocessor  110  determines that the second average sensed data has the highest value, then the microprocessor  110  determines that the location of the object is in front of the IR sensor  121 . Finally, if at step  413 , the microprocessor  110  determines that the third average sensed data has the highest value, then the microprocessor  110  determines that the location of the object is in front of the IR sensor  122 . Also, as discussed previously, the microcontroller  110  may calculate a difference between two different values recorded by two different IR sensors, and may determine that the object is placed between the two different IR sensors when the calculated difference is less than a predetermined threshold value. 
     Once the microprocessor  110  has determined the location of the object, at step  415 , the microprocessor  110  may determine the current positions of the right and left pupils  102 ,  106 . In various embodiments, the microprocessor  110  may instruct the right and left pupil sensors  140 ,  160  to respectively report the current positions of the right and left pupils  102 ,  106 . 
     At step  416 , the microprocessor  110  may effect horizontal movement of the right and left pupils  102 ,  106 . In order to do so, the microprocessor  110  may first compare the reported current positions of the right and left pupils  102 ,  106  with the location of the object, as determined in step  414 . If, based on the comparison of the reported current positions and the determined location of the object, the microprocessor  110  determines that the reported current positions of the right and left pupils  102 ,  106  correspond to the determined location of the object, then the microprocessor  110  may determine that no change to the reported current positions of the right and the left pupils  102 ,  106  is necessary, and may allow the right and left pupils  102 ,  106  to remain in their reported current positions. 
     However, if based on the comparison of the reported current positions and the determined location of the object, the microprocessor  110  determines that the reported current positions of the right and left pupils  102 ,  106  do not correspond to the determined the location of the object, then the microprocessor determines that the positions of the right and left pupils  102 ,  106  should be changed to correspond to the determined location of the object. At this time, the microprocessor  110  may instruct the right pupil motor  150  to position the right pupil  102  such that the right pupil  102  is oriented (i.e., looking) towards the determined location of the object. Similarly, the microprocessor  110  may instruct the left pupil motor  170  to position the left pupil  106  such that the left pupil  106  is oriented (i.e., looking) towards the determined the location of the object. 
     The method then proceeds to step  403 , and steps  403 - 416  are repeated. The method stops at  417 . In this way, the location of the object is determined and the horizontal movement of the pupils  102 ,  106  is effected after every occurrence of a predetermined number of cycles, the predetermined number being equal to the predetermined value of the counter (e.g., five cycles). That is, the simulator allows for determination of the location of the object and for tracking of the object by the right and left pupils  102 ,  106  after every occurrence of a predetermined number of cycles. The method  400  stops when the tracking functionality is stopped. At this time, the microcontroller  110  places both the right and left pupils  102 ,  106  in their default positions. 
       FIG. 5  illustrates an exemplary method  500  for performing simulation of horizontal movements in the independent tracking mode according to various embodiments of the present disclosure. In the independent tracking mode, the microprocessor  110  determines and effects the position of the right pupil  102  independently from the position of the left pupil  106 . In various embodiments, the microprocessor  110  effects the position of the right pupil  102  based on the readings from the first and second sensor-transmitter pairs. That is, the microprocessor  110  determines the position of the right pupil  102  based on the readings from the sensor-transmitter pair including IR sensor  120  and IR transmitter  130  and the readings from the sensor-transmitter pair including IR sensor  121  and IR transmitters  131 - 132 . Similarly, the microprocessor  110  effects the position of the left pupil  106  based on the readings from the second and third sensor-transmitter pairs. That is, the microprocessor  110  determines the position of the left pupil  106  based on the readings from the sensor-transmitter pair including IR sensor  121  and IR transmitters  131 - 132  and the readings from the sensor-transmitter pair including IR sensor  122  and IR transmitter  133 . 
     Steps  501 - 512  of method  500  are identical to the steps  401 - 412  of method  400  discussed above with respect to  FIG. 4 . As such, description of the steps will be omitted in the description of the method  500 . 
     At step  513 , the microprocessor  110  first compares the values of the average first sensed data with the average second sensed data to determine which average sensed data has the highest value. As discussed below, the microprocessor  110  effects the position of the right pupil  102  based on the determined highest value from the first comparison. Second, the microprocessor  110  compares the values of the average second sensed data with the average third sensed data to determine which average sensed data has the highest value. As discussed below, the microprocessor  110  effects the position of the left pupil  106  based on the determined highest value from the second comparison. 
     For positioning the right pupil  102 , at step  514 , the microprocessor  110  determines the location of the object to be in front of the IR sensor associated with the average sensed data having the highest value. For example, if at step  513 , the microprocessor  110  determines that the first average sensed data has the highest value, then the microprocessor  110  determines that the location of the object is in front of the IR sensor  120 . Similarly, if at step  513 , the microprocessor  110  determines that the second average sensed data has the highest value, then the microprocessor  110  determines that the location of the object is in front of the IR sensor  121 . Also, as discussed previously, the microcontroller  110  may calculate a difference between two different values recorded by different IR sensors  120 ,  121 , and may determine that the object is placed between the two different IR sensors  120 ,  121  when the calculated difference is less than a predetermined threshold value. Similarly, for positioning the left pupil  106 , at step  514 , the microprocessor  110  determines the location of the object to be in front of the IR sensor associated with the average sensed data having the highest value. For example, if at step  513 , the microprocessor  110  determines that the second average sensed data has the highest value, then the microprocessor  110  determines that the location of the object is in front of the IR sensor  121 . Similarly, if at step  513 , the microprocessor  110  determines that the third average sensed data has the highest value, then the microprocessor  110  determines that the location of the object is in front of the IR sensor  122 . Also, as discussed previously, the microcontroller  110  may calculate a difference between two different values recorded by different IR sensors  121 ,  122 , and may determine that the object is placed between the two different IR sensors  121 ,  122  when the calculated difference is less than a predetermined threshold value. 
     Once the microprocessor  110  has determined the location of the object, at step  515 , the microprocessor  110  may determine the current positions of the right and left pupils  102 ,  106 . In various embodiments, the microprocessor  110  may instruct the right and left pupil sensors  140 ,  160  to respectively report the current positions of the right and left pupils  102 ,  106 . 
     At step  516 , the microprocessor  110  may effect horizontal movement of the right and left pupils  102 ,  106 . In order to do so, the microprocessor  110  may first compare the reported current positions of the right and left pupils  102 ,  106  with the location of the object, as determined in step  514 . If, based on the comparison of the reported current positions and the determined location of the object, the microprocessor  110  determines that the reported current positions of the right and left pupils  102 ,  106  correspond to the determined location of the object, then the microprocessor  110  may determine that no change to the reported current positions of the right and the left pupils  102 ,  106  is necessary, and may allow the right and left pupils  102 ,  106  to remain in their reported current positions. 
     However, if based on the comparison of the reported current positions and the determined location of the object, the microprocessor  110  determines that the reported current positions of the right and left pupils  102 ,  106  do not correspond to the determined the location of the object, then the microprocessor determines that the positions of the right and left pupils  102 ,  106  should be changed to correspond to the determined location of the object. At this time, the microprocessor  110  may instruct the right pupil motor  150  to position the right pupil  102  such that the right pupil  102  is oriented (i.e., looking) towards the determined location of the object, as determined based on the first comparison of step  513 . Similarly, the microprocessor  110  may instruct the left pupil motor  170  to position the left pupil  106  such that the left pupil  106  is oriented (i.e., looking) towards the determined the location of the object, as determined based on the second comparison of step  513 . 
     The method then proceeds to step  503 , and steps  503 - 516  are repeated. The method stops at  517 . In this way, the location of the object is determined and the horizontal movement of the pupils  102 ,  106  is effected after every occurrence of a predetermined number of cycles, the predetermined number being equal to the predetermined value of the counter (e.g., five cycles). That is, the simulator allows for determination of the location of the object and for tracking of the object by the right and left pupils  102 ,  106  after every occurrence of a predetermined number of cycles. The method  500  stops when the tracking functionality is stopped. At this time, the microcontroller  110  places both the right and left pupils  102 ,  106  in their default positions. 
     In various embodiments, the simulator may be controlled to track objects, as discussed above, using only one pupil. For example, the simulator may be controlled to track objects using only the right pupil  102 , while the left pupil  106  may be placed in any of the exemplary positions discussed below. Further, the left pupil  106  may be moved among the exemplary positions discussed below independently with respect to the tracking of the object by the right pupil  102 . 
       FIGS. 6A-6F  illustrate exemplary positions of the right and left pupils  102 ,  106  according to various embodiments of the present disclosure. Both the above methods  400 ,  500  may be used to effect the positions of the right and left pupils  102 ,  106  illustrated in  FIGS. 6A-6F .  FIG. 6A  illustrates simulation of healthy eyes tracking an object placed to the right of the simulator  200  in front of the IR sensor  120 . As seen from  FIG. 6A , both the right and left pupils  102 ,  106  are oriented (i.e., looking) towards the object in front of the IR sensor  120 . Similarly,  FIG. 6C  illustrates simulation of healthy eyes tracking an object placed to the left of the simulator  200  in front of the IR sensor  122 . As seen from  FIG. 6C , both the right and left pupils  102 ,  106  are oriented (i.e., looking) towards the object in front of the IR sensor  122 .  FIG. 6E  illustrates simulation of healthy eyes tracking an object placed in front of the simulator  200  in front of the IR sensor  121 . As seen from  FIG. 6C , both the right and left pupils  102 ,  106  converge to be oriented (i.e., looking) towards the object in front of the IR sensor  121 . 
       FIGS. 6B, 6D, and 6F  illustrate simulations of impaired eyes and their inability to properly track an object placed in front of the simulator  200 . In various embodiments, the simulated positions of the right and left pupils  102 ,  106  illustrated in  FIGS. 6B, 6D, and 6F  may be effected by running pre-programmed routines to simulate conditions of impaired eyes. For example,  FIG. 6B  illustrates simulation of impaired eyes and their inability to properly track an object placed to the right of the simulator  200  in front of the IR sensor  120 . As seen from  FIG. 6B , the right pupil  102  is oriented (i.e., looking) towards and properly tracks the object in front of the IR sensor  120 , but the left pupil  106  remains in its default position and appears to be looking straight ahead. Similarly,  FIG. 6D  illustrates simulation of impaired eyes and their inability to properly track an object placed to the left of the simulator  200  in front of the IR sensor  122 . As seen from  FIG. 6D , the right pupil  102  is oriented (i.e., looking) towards and properly tracks the object in front of the IR sensor  122 , but the left pupil  106  remains in its default position and appears to be looking straight ahead. The inability of the left pupil  106  to properly track the object, as illustrated in  FIGS. 6B and 6D , is known as diplopia, and maybe exhibited by running a pre-programmed diplopia routine for the left eye.  FIG. 6F  illustrates simulation of impaired eyes and their inability to properly track an object placed in front of the IR sensor  121  of the simulator  200 . As seen from  FIG. 6F , the left pupil  106  is oriented (i.e., looking) towards and properly tracks the object in front of the IR sensor  121 , but the right pupil  102  remains in its default position and appears to be looking straight ahead. The inability of the right pupil  102  to properly track the object, as illustrated in  FIG. 6F , maybe exhibited by running a pre-programmed routine for the right eye. 
     In various embodiments, the pre-programmed routines may be stored on memory  180  or on an external memory (not shown). An operator of the simulator  200  may use the input interface  190  to select a pre-programmed routine to be run by the microprocessor  110 . Based on the inputs received at the input interface  190 , the microprocessor  110  may retrieve and execute the selected pre-programmed routine from the memory  180  or the external memory. The input interface  190  may be directly connected to the microprocessor  110  or maybe connected to the microprocessor  110  via another central processing unit. 
     Vertical Movement: As discussed above, the microcontroller  110  may effect movement of the right and left pupils  102 ,  106  for tracking objects in the horizontal direction. Similarly, the microcontroller  110  may also effect movement of the right and left pupils  102 ,  106  for tracking objects in the vertical direction. Simulation of vertical movement of the right and left pupils  102 ,  106  in accordance with placement and movement of an object (e.g., pencil, finger, etc.) will now be described. Simulating vertical movement includes placing the object in front of the simulator and moving the object in a vertical plane. The simulator senses the presence and the movement of the object using the five IR sensors  120 ,  121 ,  122 ,  123 ,  124  and the four IR transmitters  130 ,  131 ,  132 ,  133 , and allows for corresponding vertical movements of the right and left pupils  102 ,  106 . In various embodiments, the vertical movement of the right and left pupils  102 ,  106  may be controlled such that the right and left pupils  102 ,  106  move together. Alternatively, in various embodiments, the vertical movement of the right pupil  102  is controlled independently from the vertical movement of the left pupil  106 . 
       FIG. 7  illustrates a simulator  700  including the exemplary multipurpose eye motion trainer according to various embodiments of the present disclosure. The simulator  700  may be a manikin in the form of a human face, and may include an eye assembly. The eye assembly may include the above discussed right and left eyes  101 ,  105 , and associated circuitry to control functions to be performed by the right and left pupils  102 ,  106 . The associated circuitry for simulation of vertical movement may include five IR sensors  120 ,  121 ,  122 ,  123 ,  124 , and four infrared (IR) transmitters  130 ,  131 ,  132 ,  133  that are electrically controlled by the microcontroller  110 . Similar to the previously discussed simulator  200 , the IR sensors and the IR transmitters of the simulator  700  may be placed under silicone skin (with special openings) of the simulator  700 . This allows the simulator  700  to appear more lifelike. 
     In various embodiments, the IR sensors  120 ,  121 ,  122 , may be placed above the eyes  101 ,  105  and the IR sensors  123 ,  124  may be placed below the  101 ,  105 . For example, as shown in  FIG. 7 , the IR sensors  120 ,  121 ,  122  may be placed in a horizontal plane above the horizontal plane that includes the right and left eyes  101 ,  105 , and the IR sensors  123 ,  124  may be placed in a horizontal plane below the horizontal plane that includes the right and left eyes  101 ,  105 . Also, the IR sensors may be arranged such that IR sensors  120  and  123  share a first vertical plane and IR sensors  122  and  124  share a second vertical plane. The IR transmitters  130 ,  131 ,  132 ,  133  may be placed in a horizontal plane in close proximity to the right and left eyes  101 ,  105 . For example, as shown in  FIG. 7 , the IR transmitters  130 ,  131 ,  132 ,  133  may be placed in a horizontal plane near the horizontal plane that includes the right and left eyes  101 ,  105 . In various embodiments, the eye movement and/or eye tracking is simulated using the IR sensors  120 ,  121 ,  122 ,  123 ,  124  and the IR transmitters  130 ,  131 ,  132 ,  133 . 
     One or more of the five IR sensors  120 ,  121 ,  122  may be coupled to the sense IR response signals originating from one or more of the four IR transmitters  130 ,  131 ,  132 ,  133  to form respective sensor-transmitter pairs. For example, in the present embodiment for vertical movement, the IR sensors  120 ,  123  may be coupled to sense IR response signals resulting from IR transmissions from the IR transmitter  130 . Additionally or alternatively, the IR sensors  120 ,  123  may be coupled to sense IR response signals resulting from IR transmissions from the IR transmitter  131 . Also, the IR sensors  122 ,  124  may be coupled to sense IR response signals resulting from IR transmissions from the IR transmitter  133 . Additionally or alternatively, the IR sensors  122 ,  124  may be coupled to sense IR response signals resulting from IR transmissions from the IR transmitter  132 . An IR sensor may be coupled to an IR transmitter by tuning the sensing frequency of the IR sensor to the transmitting modulated frequency of the IR transmitter and/or by positioning the IR sensor in close proximity to the IR transmitter. The tuning of the sensing frequency to the transmitting modulated frequency results in the IR sensor being isolated from environmental conditions so as to allow accurate sensing of the IR response signal by the IR sensor. Of course, any of the one or more IR sensors may be coupled with any of the one or more IR transmitters to effect the vertical movement of the right and left pupils  102 ,  106 . 
       FIGS. 8A-8C  illustrate an exemplary range of vertical movement for the right and left pupils  102 ,  106  according to various embodiments of the present disclosure. In various embodiments, the total range of vertical movement for each of the right and left pupils  102 ,  106  may include three positions. The three positions may include a default position, an upwards position, and a downwards position.  FIG. 8A  illustrates the default positions, in which the right and left pupils  102 ,  106  may be placed to simulate a person looking substantially straight ahead.  FIG. 8B  illustrates the upwards position, in which the right and left pupils  102 ,  106  may be placed to simulate a person looking substantially upwards. Finally,  FIG. 8C  illustrates the downwards position, in which the right and left pupils  102 ,  106  may be placed to simulate a person looking substantially downwards. 
     As indicated previously, the simulation of vertical movement of the right and left pupils  102 ,  106  may be conducted in two modes—the joint tracking mode or the independent tracking mode. In the joint tracking mode, both the right and the left pupils  102 ,  106  may be controlled together such that the right and left pupils  102 ,  106  are displaced jointly in the same direction. Alternatively, in the independent tracking mode, the right pupil  102  may be controlled independently with respect to the left pupil  106  such that the right pupil  102  may move in a different direction with respect to the left pupil  106 . For example, two objects may be placed in front of the simulator  200 , such that a first object is in front of the IR sensor  120  and a second object is in front of the IR sensor  124 . In this case, the right pupil  102  may be rotated to the upwards position to be oriented (i.e., looking) towards the object in front of the IR sensor  120 , and the left pupil  106  may be rotated to the downwards position to be oriented (i.e., looking) towards the object in front of the IR sensor  124 . Finally, as discussed below in further detail, the right and left pupils  102 ,  106  may be placed in the default position based on a comparison of the values of the sensed IR response signals. 
       FIG. 9  illustrates an exemplary method  900  for performing simulation of vertical movements in the joint tracking mode according to various embodiments of the present disclosure. The method starts at step  901 . At step  902 , the microcontroller  110  places both the right and left pupils  102 ,  106  in the default positions such that both eyes appear to be looking straight ahead. For example, the microcontroller  110  may instruct the right pupil motor  150  to place the right pupil  102  in its default position and may instruct the left pupil motor  170  to place the left pupil  106  in its default position. At this time, an object (e.g., finger, pencil, etc.) may be placed in front of the simulator. 
     At step  903 , the microcontroller  110  turns on the first coupled sensor-transmitter pair of the IR sensors  120 ,  123  and the IR transmitter  130 . In various embodiments, when the first coupled sensor-transmitter pair is turned on, the IR transmitter  130  may transmit a burst of frequency modulated IR radiations. The burst may include 100 pulses, each pulse having a period of about 2 μs and a duty cycle of 50%. The transmitted pulses of IR radiations may reflect off the surface of the object in front of the simulator and the resulting IR response signals are separately sensed by the IR sensors  120 ,  123 . As previously discussed, the IR sensors  120 ,  123  may sense the IR response signals and record respective values corresponding to the respectively sensed intensities of the reflected IR response signals. At this time, the first coupled sensor-transmitter pair of the IR sensors  120 ,  123  and the IR transmitter  130  may be turned off. 
     At step  904 , the microprocessor  110  may store the IR response data sensed by the IR sensors  120 ,  123  in the electronic memory  180  as a reading of first-upwards and first-downwards sensed data. For example, the microprocessor  110  may store the IR response data sensed by the IR sensor  120  as first-upwards sensed data and may store the IR response data sensed by the IR sensor  123  as first-downwards sensed data. 
     At step  905 , the microcontroller  110  may turn on the second coupled sensor-transmitter pair of the IR sensors  122 ,  124  and the IR transmitter  133 . In various embodiments, when the second coupled sensor-transmitter pair is turned on, the IR transmitter  133  may transmit a burst of frequency modulated IR radiations. The burst may include 100 pulses, each pulse having a period of about 2 μs and a duty cycle of 50%. The transmitted pulses of IR radiations may reflect off the surface of the object in front of the simulator and the resulting IR response signals are separately sensed by the IR sensors  122 ,  124 . As previously discussed, the IR sensors  122 ,  124  may sense the IR response signals and record respective values corresponding to the respectively sensed intensities of the reflected IR response signals. At this time, the second coupled sensor-transmitter pair of the IR sensors  122 ,  124  and the IR transmitter  133  may be turned off. 
     At step  906 , the microprocessor  110  may store the IR response data sensed by the IR sensors  122 ,  124  in the electronic memory  180  as a reading of second-upwards and second-downwards sensed data. For example, the microprocessor  110  may store the IR response data sensed by the IR sensor  122  as second-upwards sensed data and may store the IR response data sensed by the IR sensor  124  as second-downwards sensed data. 
     If the one or more IR sensors are additionally paired with one or more IR transmitters, than those sensor-transmitter pairs may be turned on and their data be recorded similarly as discussed in steps  903 - 906 . For example, if one or more of the IR sensors  120 ,  123  are paired with IR transmitter  131  to form a third sensor-transmitter pair or of one or more of the IR sensors  122 ,  124  are paired with IR transmitter  132 , then these sensor transmitter pairs may be turned on and the corresponding data be recorded. 
     At step  907 , once all the sensor-transmitter pairs have been cycled through and sensed data from all the IR sensors has been recorded, the microprocessor  110  increments a counter having an initial value of zero. That is, at step  907 , the microprocessor  110  increments the counter to have a value of 1. This signifies that one cycle of collecting and recording data from all the IR sensors-transmitter pairs has been completed. 
     At step  908 , the microprocessor  110  determines whether the counter value is equal to a predetermined value. This predetermined value may be a predetermined number of cycles for collecting and recording data from all the IR sensors after which the microprocessor  110  processes the recorded data to determine the location of the object and to effect corresponding movement of the right and left pupils  102 ,  106 . In the present embodiment, the predetermined value is set to 5. That is, the data is collected and recorded from all the IR sensors for five cycles after which the microprocessor  110  processes the recorded data to determine the location of the object and to effect corresponding movement of the right and left pupils  102 ,  106 . However, any integer value greater than zero may be used as the predetermined value. 
     If the microprocessor  110  determines that the counter value is not equal to the predetermined value, then the method moves to step  903 . Alternatively, if the microprocessor  110  determines that the counter value is equal to the predetermined value, the method moves to step  909 . At this point, the microprocessor  110  has determined that five cycles of collecting and recording data from all the IR sensors has been completed. 
     At step  909 , the microprocessor  110  resets the counter such that the counter value is equal to zero. 
     At step  910 , the microprocessor  110  averages the five readings of the first-upwards sensed data and records the results as average first-upwards sensed data, averages the three readings of the first-downwards sensed data and records the results as average first-downwards sensed data, averages the three readings of the second-upwards sensed data and records the results as average second-upwards sensed data, and averages the three readings of the second-downwards sensed data and records the results as average second-downwards sensed data. In other words, the microprocessor  110  calculates the average first-upwards sensed data, the average first-downwards sensed data, the average second-upwards sensed data, and the average second-downwards sensed data. 
     At step  911 , the microprocessor  110  compares the values of the average first-upwards sensed data, the average second-upwards sensed data, the average first-downwards sensed data, and the average second-downwards sensed data. Based on the comparison, the microprocessor  110  determines which average sensed data has the highest value. 
     At step  912 , the microprocessor  110  determines the location of the object to be in front of the IR sensor associated with the average sensed data having the highest value. For example, if at step  911 , the microprocessor  110  determines that the average first-upwards sensed data or the average second-upwards has the highest value, then the microprocessor  110  determines that the location of the object is in front of either IR sensor  120  or IR sensor  122 . That is, the microprocessor  110  determines that the location of the object is in the upwards direction with respect to the default positions of the right and left pupils  102 ,  106 . Alternatively, if at step  911 , the microprocessor  110  determines that the average first-downwards sensed data or the average second-downwards sensed data has the highest value, then the microprocessor  110  determines that the location of the object is in front of the IR sensor  123  or IR sensor  124 . That is, the microprocessor  110  determines that the location of the object is in the downwards direction with respect to the default positions of the right and left pupils  102 ,  106 . 
     Also, the microcontroller  110  may calculate a difference between the two greatest average values, and may determine that the object is placed between the two different IR sensors associated with the two greatest average values when the calculated difference is less than a predetermined threshold value. For example, if at step  911 , the microprocessor  110  determines that the average first-upwards (or second-upwards) sensed data and the average first-downwards (or second-downwards) sensed data are the two greatest average values, then the microprocessor  110  may calculate a difference between the average first-upwards (or second-upwards) sensed data and the average first-downwards (or second-downwards) sensed data. The microprocessor  110  may then determine that the vertical location of the object is in between IR sensors  120  and  123  (or between IR sensors  122  and  124 ) when the calculated difference is less than a predetermined threshold value. 
     Once the microprocessor  110  has determined the location of the object, at step  913 , the microprocessor  110  may determine the current positions of the right and left pupils  102 ,  106 . In various embodiments, the microprocessor  110  may instruct the right and left pupil sensors  240 ,  260  to respectively report the current positions of the right and left pupils  102 ,  106 . 
     At step  914 , the microprocessor  110  may effect vertical movement of the right and left pupils  102 ,  106 . In order to do so, the microprocessor  110  may first compare the reported current positions of the right and left pupils  102 ,  106  with the location of the object, as determined in step  912 . If, based on the comparison of the reported current positions and the determined location of the object, the microprocessor  110  determines that the reported current positions of the right and left pupils  102 ,  106  correspond to the determined location of the object, then the microprocessor  110  may determine that no change to the reported current positions of the right and the left pupils  102 ,  106  is necessary, and may allow the right and left pupils  102 ,  106  to remain in their reported current positions. 
     However, if based on the comparison of the reported current positions and the determined location of the object, the microprocessor  110  determines that the reported current positions of the right and left pupils  102 ,  106  do not correspond to the determined location of the object, then the microprocessor determines that the positions of the right and left pupils  102 ,  106  should be changed to correspond to the determined location of the object. At this time, the microprocessor  110  may instruct the right and left pupil motors  250 ,  270  to position the right and left pupils  102 ,  106  such that the right and left pupils  102 ,  106  are oriented (i.e., looking) towards the determined location of the object. 
     The method then proceeds to step  903 , and steps  903 - 914  are repeated. The method stops at  915 . In this way, the location of the object is determined and the vertical movement of the pupils  102 ,  106  is effected after every occurrence of a predetermined number of cycles, the predetermined number being equal to the predetermined value of the counter (e.g., five cycles). That is, the simulator  700  allows for determination of the location of the object and for tracking of the object by the right and left pupils  102 ,  106  after every occurrence of a predetermined number of cycles. The method  900  stops when the tracking functionality is stopped. At this time, the microcontroller  110  places both the right and left pupils  102 ,  106  in their default positions. 
       FIG. 10  illustrates an exemplary method  1000  for performing simulation of vertical movements in the independent tracking mode according to various embodiments of the present disclosure. In the independent tracking mode, the microprocessor  110  determines and effects the position of the right pupil  102  independently from the position of the left pupil  106 . In various embodiments, the microprocessor  110  effects the position of the right pupil  102  based on the readings from the first sensor-transmitter pair. That is, the microprocessor  110  determines the position of the right pupil  102  based on the readings from the sensor-transmitter pair including IR sensors  120 ,  123  and IR transmitter  130  (and the readings from the sensor-transmitter pair including IR sensors  120 ,  123  and IR transmitter  131 , if paired). Similarly, the microprocessor  110  effects the position of the left pupil  106  based on the readings from the second sensor-transmitter pair. That is, the microprocessor  110  determines the position of the left pupil  106  based on the readings from the sensor-transmitter pair including IR sensors  122 ,  124  and IR transmitter  133  (and the readings from the sensor-transmitter pair including IR sensors  122 ,  124  and IR transmitter  132 , if paired). 
     Steps  1001 - 1010  of method  1000  are identical to the steps  901 - 910  of method  900  discussed above with respect to  FIG. 9 . As such, description of the steps will be omitted in the description of the method  1000 . 
     At step  1011 , the microprocessor  110  first compares the values of the average first-upwards sensed data with the average first-downwards sensed data to determine which average sensed data has the highest value. As discussed below, the microprocessor  110  effects the position of the right pupil  102  based on the determined highest value from the first comparison. Second, the microprocessor  110  compares the values of the average second-upwards sensed data with the average second-downwards sensed data to determine which average sensed data has the highest value. As discussed below, the microprocessor  110  effects the position of the left pupil  106  based on the determined highest value from the second comparison. 
     For positioning the right pupil  102 , at step  1012 , the microprocessor  110  determines the location of the object to be in front of the IR sensor associated with the average sensed data having the highest value. For example, if at step  1011 , the microprocessor  110  determines that the average first-upwards sensed data has the highest value, then the microprocessor  110  determines that the location of the object is in front of the IR sensor  120 . Similarly, if at step  1011 , the microprocessor  110  determines that the average first-downwards sensed data has the highest value, then the microprocessor  110  determines that the location of the object is in front of the IR sensor  123 . Similarly, for positioning the left pupil  106 , at step  1012 , the microprocessor  110  determines the location of the object to be in front of the IR sensor associated with the average sensed data having the highest value. For example, if at step  1011 , the microprocessor  110  determines that the average second-upwards sensed data has the highest value, then the microprocessor  110  determines that the location of the object is in front of the IR sensor  122 . Similarly, if at step  1011 , the microprocessor  110  determines that the average second-downwards sensed data has the highest value, then the microprocessor  110  determines that the location of the object is in front of the IR sensor  124 . Also, as discussed previously, the microcontroller  110  may calculate a difference between two different values recorded by two different IR sensors, and may determine that the object is placed between the two different IR sensors when the calculated difference is less than a predetermined threshold value. 
     Once the microprocessor  110  has determined the location of the object, at step  1013 , the microprocessor  110  may determine the current positions of the right and left pupils  102 ,  106 . In various embodiments, the microprocessor  110  may instruct the right and left pupil sensors  240 ,  260  to respectively report the current positions of the right and left pupils  102 ,  106 . 
     At step  1014 , the microprocessor  110  may effect vertical movement of the right and left pupils  102 ,  106 . In order to do so, the microprocessor  110  may first compare the reported current positions of the right and left pupils  102 ,  106  with the location of the object, as determined in step  1012 . If, based on the comparison of the reported current positions and the determined location of the object, the microprocessor  110  determines that the reported current positions of the right and left pupils  102 ,  106  correspond to the determined location of the object, then the microprocessor  110  may determine that no change to the reported current positions of the right and the left pupils  102 ,  106  is necessary, and may allow the right and left pupils  102 ,  106  to remain in their reported current positions. 
     However, if based on the comparison of the reported current positions and the determined location of the object, the microprocessor  110  determines that the reported current positions of the right and left pupils  102 ,  106  do not correspond to the determined location of the object, then the microprocessor determines that the positions of the right and left pupils  102 ,  106  should be changed to correspond to the determined location of the object. At this time, the microprocessor  110  may instruct the right pupil motor  250  to position the right pupil  102  such that the right pupil  102  is oriented (i.e., looking) towards the determined location of the object, as determined based on the first comparison of step  1011 . Similarly, the microprocessor  110  may instruct the left pupil motor  270  to position the left pupil  106  such that the left pupil  106  is oriented (i.e., looking) towards the determined the location of the object, as determined based on the second comparison of step  1011 . 
     The method then proceeds to step  1003 , and steps  1003 - 1014  are repeated. In this way, the location of the object is determined and the vertical movement of the pupils  102 ,  106  is effected after every occurrence of a predetermined number of cycles, the predetermined number being equal to the predetermined value of the counter (e.g., five cycles). That is, the simulator allows for determination of the location of the object and for tracking of the object by the right and left pupils  102 ,  106  after every occurrence of a predetermined number of cycles. The method  1000  stops at step  1015  when the tracking functionality is stopped. At this time, the microcontroller  110  places both the right and left pupils  102 ,  106  in their default positions. 
     In various embodiments of the methods  900 ,  1000 , the microcontroller  110  may, in addition to comparing the calculated average sensed data values, calculate a difference between the average sensed data values to determine the location of the object. For example, with respect to method  1000 , the microcontroller  110  may calculate a difference between the average first-upwards (and/or second-upwards) sensed data and the average first-downwards (and/or second-downwards) sensed data. The microcontroller  110  may then compare the calculated difference with a predetermined threshold value. Based on this comparison, if the microcontroller  110  determines that the calculated difference is greater than the predetermined threshold value, then the method proceeds to step  1012 , as discussed above with respect to  FIG. 10 . However, if the microcontroller  110  determines that the calculated difference is equal to or lower than the predetermined threshold value, then the microcontroller  110  may determine that the object is located substantially in between the IR sensor  120  (or IR sensor  122 ) and IR sensor  123  (or IR sensor  124 ). Based on this determination of the location of the object, the microcontroller  110  may place the right and left pupils  102 ,  106  in the default positions to be oriented (i.e., looking) towards that determine location of the object. 
     In various embodiments, the simulator may be controlled to track objects, as discussed above, using only one pupil. For example, the simulator may be controlled to track objects using only the right pupil  102 , while the left pupil  106  may be placed in any of the exemplary positions discussed below. Further, the left pupil  106  may be moved among the exemplary positions discussed below independently with respect to the tracking of the object by the right pupil  102 . 
     In various embodiments, the simulated positions of the right and left pupils  102 ,  106  may be effected by running pre-programmed routines to simulate conditions of normal or impaired eyes. For example, similar to the conditions illustrated in  FIGS. 6A-F , vertical positions of the right and left pupils  102 ,  106  may be effected by running pre-programmed routines to simulate conditions of normal or impaired eyes. In addition, a combination of horizontal and vertical positions of the right and left pupils  102 ,  106  may be effected by running pre-programmed routines to simulate rolling of the right and left pupils  102 ,  106  in a circular motion. 
     In various embodiments, the pre-programmed routines may be stored on memory  180  or on an external memory (not shown). An operator of the simulator  200  may use the input interface  190  to select a pre-programmed routine to be run by the microprocessor  110 . Based on the inputs received at the input interface  190 , the microprocessor  110  may retrieve and execute the selected pre-programmed routine from the memory  180  or the external memory. The input interface  190  may be directly connected to the microprocessor  110  or maybe connected to the microprocessor  110  via another central processing unit. 
     Pupillary Change: Pupillary change may be described as a physiological response in which the size of the iris of the pupil changes in response to light conditions sensed by the human nervous system. The change in the size of iris may be constriction or dilation. The size of the iris reduces during constriction and increases during dilation. Constriction occurs in high light (i.e., bright) conditions when the pupil allows a limited amount of light into the eye, and dilation occurs in low light (i.e., dark) conditions when the pupil allows more light into the eye. Pupillary change is an important medical indicator for healthy eyes in that healthy eyes exhibit consensual light reflex which occurs, for example, when the iris in one eye not directly stimulated reacts to stimulation of the iris in the other eye. In various embodiments, the presently disclosed simulator realistically replicates the change in size of an iris in a human eye in a way that is useful for medical educational and diagnostic purposes. 
       FIG. 11A  illustrates an electro-mechanical block diagram  1100  of the simulator according to various embodiments of the present disclosure. The simulator (see  FIG. 12 ) may be a manikin in the form of a human face, and may include the eye assembly discussed above. The eye assembly may include the right eye  101  of the simulator, the left eye  105  of the simulator, and associated circuitry to control functions to be performed by the right and left eyes  101 ,  105 . For pupillary change functions, the simulator may include the microcontroller  110  electrically connected to a right light sensor  1110 , a right iris motor  1111 , a left light sensor  1120 , and a left iris motor  1121  to actuate constriction or dilation. The right/left iris motors  1111 ,  1121  are respectively connected to right/left iris size sensors  1112 ,  1122  via right/left rotating arms  1113 ,  1123 . The right/left rotating arms  1113 ,  1123  are respectively connected to right/left circular apertures  1114 ,  1124 , which represent the right/left irises in the right/left eyes  101 ,  105 . The right/left apertures  1114 ,  1124  are adjacently placed next to right/left pupil backgrounds  1115 ,  1125 , respectively. In various embodiments, the electro-mechanical components to effect pupillary changes are coupled to each other coaxially. 
     As seen from  FIG. 11B , the above components for actuating the constriction or dilation of the right and left apertures  1114 ,  1124  are placed inside the right and left eyes  101 ,  105 . This allows the control associated with the constriction or dilation of the irises  1114 ,  1124  to be independent from the horizontal or vertical movements of the right and left pupils  102 ,  106  discussed above with respect to  FIGS. 1-10 . In various embodiments, the pupil dilation of each of the right and left eyes  101 ,  105  is controlled at least partially based on an amount of light received by the optical sensors  1110 ,  1120  positioned within the eyes. That is, based on the amount of light received by the optical sensors  1110 ,  1120 , the microcontroller  110  activates the constriction or dilation of the irises  1114 ,  1124 . In various embodiments, the rate of change or responsiveness of the irises can be slowed to simulate an abnormal medical condition that would result in slowed pupil constriction or dilation. In this manner, pupillary changes are simulated for medical and diagnostic purposes. A maximum size of the iris and/or the rate of change or dilation of the iris may be controlled by the control system illustrated in  FIG. 11 . The right and left eyes  101  can be independently constricted or dilated in some instances. 
     In various embodiments, the optical sensor  1110  senses the light conditions associated with an experienced by the right eye  101 , and the optical sensor  1120  senses the light conditions associated with and experienced by the left eye  105 . Upon sensing the light conditions, the optical sensors  1110 ,  1120  respective electrical signals transmit information regarding the sensed light conditions to the microprocessor  110 . The microprocessor  110  receives the respective electrical signals, and processes the information regarding the sensed light conditions to determine whether to change the circular sizes of the right iris and/or the left iris  1114 ,  1124 . In various embodiments, the microprocessor  110  may determine to change the circular size of the right iris  1114  jointly or independently with respect to the determination to change circular size of the left iris  1124 . 
     The microprocessor  110  may send electrical signals to the right/left iris motors  1111 ,  1121  to actuate the increase or decrease in the circular size of the right iris and/or the left iris  1114 ,  1124 . The shafts of the right/left iris motors  1111 ,  1121  may be respectively coupled to right/left rotating arms  1113 ,  1123  such that rotation of the motors effects rotation of the rotating arms. Further, the right/left rotating arms  1113 ,  1123  may be respectively coupled to the circular apertures that act as the right/left irises  1114 ,  1124  such that rotation of the rotating arms allows for increase or decrease in the size of the circular apertures. For example, when an iris motor ( 1111  or  1121 ) rotates in a first direction, it effects rotation of the rotating arm ( 1113  or  1123 ) to increase the circular size of a circular aperture ( 1114  or  1124 ). Similarly, when the iris motor ( 1111  or  1121 ) rotates in a second direction, it effects rotation of the rotating arm ( 1113  or  1123 ) to decrease the circular size of a circular aperture ( 1114  or  1124 ). The increase or decrease in the size of the circular apertures along with the pupil backgrounds  1115 ,  1125  visually simulates constriction or dilation of an iris in a human eye. 
       FIGS. 12A-12C  illustrate exemplary changes in the size of the iris according to various embodiments of the present disclosure. The total range of change in the size of the iris may be from 1 mm in diameter when totally constricted to 8 mm in diameter when totally dilated. The total range may include three illustrated positions—a default size, a totally constricted size, and a totally dilated size. For example,  FIG. 12A  shows the default size of the iris, which may be about 4 mm in diameter.  FIG. 12B  illustrates the totally constricted size of the iris, which may be about 1 mm in diameter. Finally,  FIG. 12C  illustrates the totally dilated size of the iris, which may be about 8 mm in diameter. 
       FIG. 13  illustrates an exemplary method  1300  for performing simulation of pupillary changes for a given eye (right or left) according to various embodiments of the present disclosure. The method starts at step  1301 . In operation, the given eye may be directly stimulated by subjecting it to specific lighting conditions. 
     At step  1302 , upon sensing the specific light conditions, the microcontroller  110  may receive electrical signals transmitted from the light sensor placed inside the eye in response to being subjected to the specific lighting conditions. For example, when the eye is subjected to bright lighting conditions, the light sensor may transmit electrical signals informing the microcontroller  110  that the eye is subjected to bright light conditions, and when the eye is subjected to dark lighting conditions, the light sensor transmits electrical signals informing the microcontroller  110  that the eye is subjected to the dark lighting conditions. Under normal lighting conditions, the light sensor may transmit electrical signals informing the microcontroller  110  that the eyes subjected to normal lighting conditions. 
     At step  1303 , upon receiving the electrical signals, the microcontroller  110  may determine whether to constrict or to dilate the iris of the eye. For example, when the light sensor (e.g., photodiode) informs the microcontroller  110  that the eye is subjected to bright lighting conditions, the microcontroller  110  may determine that the iris of the eye should be constricted, and when the light sensor informs the microcontroller  110  is subjected to dark lighting conditions, the microcontroller  110  may determine that the iris of the eye should be dilated. 
     At step  1304 , based on this information, the microcontroller  110  may determine a size of the iris to be effected. For example, the electrical signals may include information regarding and intensity of the specific lighting conditions. Based on this information, the microcontroller  110  may determine a size of the iris to be effected to correspond to the intensity of the specific lighting conditions. 
     At step  1305 , the microcontroller  110  may determine the current size of the iris of the eye. For example, the microcontroller  110  may instruct the iris size sensor for the given eye to report the current size of the iris of the eye. Once the microcontroller  110  has determined the current size of the iris of the eye, the method proceeds to step  1306 . 
     At step  1306 , the microcontroller  110  may first compare the current size of the iris with the size of the iris to be effected, as determined in step  1303 . 
     At step  1307 , based on the comparison of the current size and the determined size of the iris, the microprocessor  110  may determine whether to change the size of the iris. For example, if the microprocessor  110  determines that the current size of the iris corresponds to the determined size of the iris, then the microprocessor  110  may determine that no change to the current size of the iris is necessary. The method proceeds to step  1302 . As such, the microprocessor  110  may allow the iris to remain in its reported current size. However, if based on the comparison of the current size and the determined size of the iris, the microprocessor  110  determines that the current size does not correspond to the determined size of the iris, then the microprocessor determines that the size of the iris should be changed to the determined size. The method proceeds to step  1308 . 
     At step  1308 , the microprocessor  110  may operate the iris motor of the eye to effect the constriction or the dilation of the iris of the eye. 
     The iris motor may be a geared motor coupled to a rotating arm that enables the circular aperture of the eye to circularly reduce in size when simulating constriction and to circularly increase in size when simulating dilation. In various embodiments the circular aperture may constrict to a circular size of about 1 mm in diameter and may dilate to a circular size of about 8 mm in diameter. That is, the circular aperture may have a circular size between 1 mm in diameter to 8 mm in diameter. In its default position, which may simulate normal light conditions, the circular aperture may have a circular size of about 4 mm in diameter. Also, the circular aperture may be of a blue or brown color to simulate a blue or brown iris in the eye. The circular aperture is attached to the background that simulates a pupil of a human eye. As the circular size of the aperture is changed with the background simulating the pupil, realistic replication of an iris (of a human eye) changing circular size in response to the surrounding lighting conditions is achieved. 
     At optional step  1309 , once the size of the iris has been changed to the determined size, the microcontroller  110  may determine that the other eye that is not directly simulated by the specific light conditions may also need to be constricted or dilated in response to the specific light conditions discussed above. 
     At step  1310 , the microcontroller  110  may effect constriction or dilation of the iris in the other eye by following similar steps as discussed above for the given eye that is directly simulated by the specific light conditions. Further, the microcontroller  110  may effect constriction or dilation of the iris in the other eye by a different amount with respect to the given eye. 
     Once the sizes of both the irises have been changed to the determined sizes of the irises, the method returns to step  1302 , and steps  1302 - 1309  may be repeated. The method stops at  1311 . In this way, the simulator realistically replicates the change in size of an iris in a human eye in a way that is useful for medical educational and diagnostic purposes. The method  1300  stops when the pupillary change functionality is stopped. At this time, the microcontroller  110  places both the right and left irises  1114 ,  1124  in their default sizes to simulate normal lighting conditions. 
     Blinking: Blinking maybe described as a physiological response which involves the closing and opening of an eyelid of an eye. Blinking is a normal reflex and protects the eyes from dryness, and also regulates tears to nourish and cleanse the surface of the eye. The blinking rate, which is the rate at which an eyelid closes and opens per unit of time, is an important medical indicator for healthy eyes. For example, healthy eyes exhibit a low rate of blinking of about 5-10 blinks per minute. On the other hand, an excessive blinking rate of about 30 blinks per minute and higher indicates unhealthy conditions such as dry eyes, nervousness, eye irritation, or psychiatric conditions. In various embodiments, the presently disclosed simulator realistically replicates the blinking of a human eye in a way that is useful for medical educational and diagnostic purposes. 
     In various embodiments, the simulator is configured to simulate blinking of human eyes. For example, the eyelids  103 ,  107  are operated to open and close to simulate blinking. In various embodiments, the rate, pattern, and speed of blinking are controlled by the control system illustrated in  FIG. 14 . In some instances the rate of blinking ranges from 5 blinks per minute to 30 blinks per minute. However, ranges outside of this are used in some embodiments. Further, the eyes can be maintained in an open position or a closed position. The speed of the blinks can be controlled as well. In some instances, the speed of each blink from an open position to a closed position and back to the open position is approximately 200 ms. However, the speed of the blinks can be increased or decreased as desired. 
       1401   FIG. 14  illustrates an electro-mechanical block diagram  1400  of the simulator according to various embodiments of the present disclosure. As previously discussed, the eye assembly may include the right eye  101  having the right eyelid  103 , the left eye  105  having the left eyelid  107 , and associated circuitry to control functions to be performed by the right and left eyes  101 ,  105 . In various embodiments, the right and left eyelids  103 ,  107  are moved together to simulate blinking. For blinking functions, the simulator may include the microcontroller  110  electrically connected to an eyelid position sensor  1401  and a blink motor  1410  to actuate the right and left eyelids  103 ,  107  to simulate blinking. In various embodiments, the blinking of the right and left eyelids  103 ,  107  may be controlled independently, and each eyelids may have a dedicated blink motor to actuate the independently simulate blinking. The blinking may involve the right and left eyelids  103 ,  107  moving between an open position and a closed position, with the open position being the default position of the eyelids  103 ,  107 . The blink motor  1410  may be attached to a four bar linkage  1420  capable of relaying the torque of the blink motor  1410  to two rotatable curved parts  1403 ,  1407 . The rotatable curved parts  1403 ,  1407  may be covered by silicone material serving as the eyelids  103 ,  107 . As such, when the microcontroller  110  operates the blink motor  1410  to rotate, the four bar linkage  1420  relays the torque to the two rotatable curved parts  1403 ,  1407  (i.e., the eyelids  103 ,  107 ) to simulate human blinking motion. 
     The microcontroller  110  may instruct the eyelid position sensor  1401  to report the current position of the two rotatable curved parts  1403 ,  1407  (i.e., the eyelids  103 ,  107 ). Further, the microcontroller  110  may continuously receive electrical signals from the eyelid position sensor  1401  to continuously monitor positions of the eyelids  103 ,  107 . In various embodiments, the microcontroller  110  may continuously monitor the position of the eyelids  103 ,  107  when the blinking is actuated between the open and closed positions. During the monitoring, when the microcontroller  110  determines that the eyelids  103 ,  107  have reached the closed position, the microcontroller  110  may transmit electrical signals to reverse the rotation of the blink motor  1410  so that the eyelids  103 ,  107  are rotated to the open position. 
     In various embodiments, the sensors  140 ,  160 ,  240 ,  260 ,  1112 ,  1122 ,  1401  discussed above with respect to sensing positions of the pupils, size of the pupils, and positions of the eyelids may be rotary potentiometers. The rotary potentiometers may be electro-mechanically connected to the microcontroller  110  and to shafts of the various motors discussed above. The rotary potentiometers may be used as both the dividers to obtain adjustable output voltages. As a motor shaft rotates, the wiper (i.e., the sliding contact) of the corresponding rotary potentiometer slides along the resistive body between the terminals of the potentiometer. The sliding of the wiper provides a reading of the adjustable output voltage. 
     The microcontroller  110  monitors the adjustable output voltage, and refers to respective predetermined associations between output voltages and positions of the pupils, size of the pupils, or the positions of the eyelids to determine the respective current positions. For example, the microcontroller  110  may monitor the adjustable output voltage output by the right pupil position sensor  140 , and refer to a predetermined association between the output voltage of the right pupil position sensor  140  and position of the right pupil  102  to determine a current position of the right pupil  102 . Similarly, the microcontroller  110  may monitor the adjustable output voltage output by the eyelid position sensor  1401 , and refer to a predetermined association between the output voltages of the eyelid position sensor  1401  and positions of the right and left eyelids  103 ,  107  to determine current positions of the right and left eyelids  103 ,  107 . Finally, the microcontroller  110  may monitor the adjustable output voltage output by the left iris size sensor  1122 , and refer to a predetermined association between the output voltages of the left iris size sensor  1122  and sizes of the left iris  1124  to determine a current size of the iris  1124 . In addition to determining current positions and sizes, as discussed above, the microcontroller  110  may also use the monitored adjustable output voltages to confirm that the effected changes in the positions of the pupils and/or the eyelids and in the sizes of the irises have been accurately effected. 
     Mechanisms: As discussed previously, the microcontroller  110  may effect changes in the positions of the right and left pupils  102 ,  106  to simulate horizontal movements, vertical movements, and/or combination of horizontal and vertical movements. These movements of the right and left pupils  102 ,  106  in the various directions may be achieved by using a two axis gimbal, which is mounted to another rotating gimbal so that both the gimbals may rotate simultaneously to orient the pupils in any combination of horizontal and vertical rotation. This exemplary configuration of the gimbals also allows the vertical movement of the pupils  102 ,  106  to be independent from the horizontal movement of the pupils  102 ,  106 . In various embodiments, the simulators according to the present disclosure may include two mechanisms to effect displacement of the right and left pupils  102 ,  106  in the various directions. For example, simulators may include a right mechanism to effect displacement of the right pupil  102  and a left mechanism to effect displacement of the left pupil  106 . 
       FIG. 15  illustrates an exemplary mechanism  1500  used for horizontal movement of a given pupil (right or left) according to various embodiments of the present disclosure. In various embodiments, the mechanism  1500  effects movement of a given pupil (right or left) in the horizontal direction. Each mechanism  1500  may include a pupil position motor  1510  ( 150  or  170 ), a pupil position sensor  1520  ( 140  or  160 ), a gimbal  1530 , a lever  1540 , and bearings  1550  for fixedly attaching the gimbal  1530  to a frame  1560  connected to the backend of a given pupil  102 ,  106 . The motor assembly  1510  is electronically connected to the microcontroller  110 . As discussed previously, the microcontroller  110  may instruct the pupil position motor  1510  to change the horizontal position of the right or left pupil. Once instructed, the pupil position motor  1510  rotates to effect movement of the lever  1540  that is attached to the gimbal  1530 . As the lever  1540  moves, the gimbal  1530  rotates horizontally about an axis passing through the bearings  1550 . As the gimbal  1530  rotates, the fixedly attached frame  1560  and, therefore, the pupil  102 ,  106  rotates within the exemplary range of horizontal movement for the right and left pupils  102 ,  106  illustrated in  FIG. 3A . The right and left pupils  102 ,  106  may be controlled together. Alternative, the right and left pupils  102 ,  106  may be controlled independently to allow simulation of eyes converging towards the nose or to exhibit diplopia. 
       FIGS. 16A-B  illustrate exemplary mechanisms  1600  used for vertical movement of a given pupil (right or left) according to various embodiments of the present disclosure. In various embodiments, the mechanism  1600  effects movement of a given pupil (right or left) in the vertical direction. Each mechanism  1600  may include a pupil position motor  1610  ( 250  or  270 ), a pupil position sensor  1650  ( 240  or  260 ), a gimbal assembly  1620 , a lever  1630 , a frame loop  1640  of the frame  1560  connected to the backend of a given pupil  102 ,  106 . As discussed previously, the microcontroller  110  may instruct the pupil position motor  1610  to change the vertical position of the right or left pupil. Once instructed, the pupil position motor  1610  rotates to effect movement of the gimbal assembly  1620  that is attached to the lever  1630 . As the lever  1630  moves, the crank arm  1630  is moved. As seen in  FIGS. 16A-B , the crank arm  1630  is curved at the end proximal to the pupil  102 ,  106  and is attached to the frame loop  1640 . The frame loop  1640  is either part of the frame  1564  is fixedly attached to the frame  1560 . The movements of the crank arm  1630  attached to the frame loop  1640  rotate the pupil  102 ,  106  within the exemplary range of vertical movement for the right and left pupils  102 ,  106  illustrated in  FIGS. 8A-C . 
     A center at the back of the frame  1560  may be connected to a center of the gimbal  1530 , the connection serving as a fulcrum for the vertical rotation of the pupil  102 ,  106 . As shown in  FIG. 16B , the right and left pupils  102 ,  106  may be controlled together by using a hooked rod  1660  connecting the mechanisms for both the pupils  102 ,  106 . Alternatively, the right and left pupils  102 ,  106  may be controlled independently to allow simulation of previously discussed pupil movements. In order to make the vertical rotation of the pupil  102 ,  106  independent from the horizontal rotation of the pupil  102 ,  106 , the movement of the vertical gimbal  1620  should be unaffected by the horizontal rotation of the gimbal  1530 . This may be achieved by using the crank arm  1630  that does not interfere with the horizontal rotation of the gimbal  1530 . The mechanism  1600  also includes mechanical hard stops at both ends to ensure safe limits to the vertical rotation of the pupils  102 ,  106 . 
     In human eyes, the right/left eyelids  103 ,  107  should also move upward and downward along with the upward and downward movement of the right/left pupils  102 ,  106 . This is called eyelid following. It is critical that medical simulators test and diagnose this phenomenon. The present simulator mimics the lifelike motion of the eyelids during eyelid following. 
     The motion of the right/left eyelids  103 ,  107  relates to the vertical motion of the right/left pupils  102 ,  106 . As the right/left pupils  102 ,  106  move upward or downward, the right/left eyelids  103 ,  107  follow the right/left pupils  102 ,  106  to maintain a constant distance between the pupils and the eyelids. For example, when the right pupil  102  moves downward, the right eyelid  103  follows the right pupil to maintain a constant distance between the right pupil  102  and the right eyelid  103 . In this case, the right eyelid  103  moves downward towards its closed position but remains open enough to maintain the constant distance. Similarly, when the left pupil  106  moves upward, the left eyelid  107  follows the right pupil to maintain a constant distance between the left pupil  106  and the left eyelid  107 . In this case, the left eyelid  107  moves upwards past its open position to maintain the constant distance. When the right/left pupils  102 ,  106  are looking substantially straight, the right/left eyelids are positioned in their nominal open positions. The simulator may employ the same mechanisms as employed for the eyelid blinking and vertical motion of the pupils discussed above. The right/left pupils  102 ,  106  act as the master since the right/left eyelids  103 ,  107  react to the movement of the right/left pupils  102 ,  106 . 
     In addition to the above discussed preprogrammed routines, the simulator is configured to allow direct, real-time control of the positioning of the right/left pupils  102 ,  106  by using computer input devices, such as, the keyboard, mouse, or joystick connected through the input/output interface  190 . The user may move the right/left pupils  102 ,  106  to any position that is a normal human lifelike position. In various embodiments, a graphical display may be presented to the user on the display connected through the input/output interface  190 . The graphical display may depict an eye with a pupil and an iris. In various embodiments, a user may control the positioning of the right/left pupils  102 ,  106  on the simulator by controlling the position of the pupil of the graphical eye. The user may control the pupil of the graphical eye by moving the mouse cursor or the joystick to change the position of the pupil of the graphical eye, and thereby allow the microcontroller  110  to effect movement of the right pupil  102 , the left pupil  106 , or both. The user may also use a finger or stylus on a touch screen display and control the pupil of the graphical eye to change the position of the right pupil  102 , the left pupil  106 , or both. 
     As the cursor/joystick/finger moves, the microcontroller  110  receives the electrical signals associated with these movements through the input/output interface  190 , and effects corresponding movements of the right/left pupils  102 ,  106 . For example, a computer or processor connected to the cursor/joystick/finger provides the location of the cursor/joystick/finger in reference to the pupil of the graphical eye, and the microcontroller  110  converts the location of the pupil to the corresponding simulator positions of the right/left pupils  102 ,  106 . The microcontroller may employ a pre-stored map having locations on the display screen depicting the graphical eye plotted to corresponding locations of the right/left pupils  102 ,  106  on the simulator. In various embodiments, when the cursor/joystick/finger is moved outside the graphical eye, the right/left pupils  102 ,  106  may be positioned in their default positions. The microcontroller  110  is configured to effect movements of the right/left pupils  102 ,  106  in real-time in any direction (e.g., vertical, horizontal, or both) either independently or together with respect to each other. 
     The system may also include pre-programmed patterns for the eye assemblies (including combinations of movement, dilation, and/or blinking) to simulate various patient scenarios. The system may also be configured to allow combinations of real-time control via cursor, joystick or other input with the pre-programmed patterns. For example, the pre-programmed pattern may continue until a control input for a real-time control is received. Similarly, the system may also be configured to allow combinations object tracking with the pre-programmed patterns. For example, the pre-programmed pattern may continue until a tracking object is detected by one of the sensors and/or an input for a object tracking is received from a user. 
     Although illustrative embodiments have been shown and described, a wide range of modification, change, and substitution is contemplated in the foregoing disclosure and in some instances, some features of the present disclosure may be employed without a corresponding use of the other features. It is understood that such variations may be made in the foregoing without departing from the scope of the embodiment. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the present disclosure.