Patent Publication Number: US-9851813-B2

Title: Force sensing for fine tracking control of mouse cursor

Description:
FIELD OF THE INVENTION 
     The invention relates to input devices for computing systems, and more particularly, to methods and apparatuses for fine control of navigational objects, such as a cursors. 
     BACKGROUND OF THE INVENTION 
     An input device can be manipulated by a user to generate input data in a computer system. Typically, an input device is positioned on a surface and moved relative to that surface, but other forms of input devices operating in different fashions are also available. The operations performed on an input device generally correspond to moving a navigational object (e.g., a cursor) and/or making selections on a display screen. There are many kinds of electronic input devices, such as buttons or keys, pens, digitizing pads, game controllers, trackballs, touch screens, touch pads, mice, and the like. A “mouse” is a common type of input device that functions as a pointing device for a computer by detecting motion imparted by a user. The mouse&#39;s motion is typically translated into motion of a navigational object (e.g., cursor) on a graphical user interface (GUI) provided on a display screen. A mouse generally comprises a small case, held in a user&#39;s hand, with one or more input buttons. Additionally, a mouse may have other elements, such as a scroll wheel, that allow a user to perform enhanced operations. 
     When tracking the motion of an electronic input device, there can be a wide range of motions from large coarse motions to small fine motions. For example, a user may perform a large, coarse motion with the input device to move a navigational object from one side of a graphical display to another side of the graphical display. In contrast, a user may perform a small, fine motion with the input device to move the navigational object a relatively small number pixels (e.g., 1 to 100 pixels). A user may want to move a navigational object a relatively small number of pixels when homing in on a small target area, such as a space between two adjacent characters in a text file. However, many conventional mouse-type input devices slip or jerk when the user attempts to move the input device in small increments due to static/kinetic friction transitions. This can cause unstable control of the navigational object. 
     Accordingly, fine control of a navigational object using an electronic input device can be a difficult challenge when the input device is also used for coarse cursor control. 
     SUMMARY OF THE INVENTION 
     Various aspects of the present invention relate systems and methods for controlling a navigational object using an input device. A system in accordance with one embodiment includes a motion-based input device having a force detection module operable to detect a lateral force applied to the input device. The system further includes a processor coupled to the force detection module. The processor is operable to generate navigational object movement information based on the detected lateral force. The navigational object movement information may include moving the navigational object in relatively small increments or in relatively large increments. 
     In accordance with a further embodiment, a computer readable medium capable of storing computer executable instructions is provided. When executed by a computer, the computer readable medium includes code for detecting a lateral force applied to the input device and detecting a motion of the input device relative to a surface. In addition, the computer readable medium includes code for calculating a change in position of the navigational object based on a detected lateral force contribution and a detected motion contribution. 
     In one embodiment, a method for controlling movement of a navigational object displayed on a user graphical interface is provided. The method includes measuring a lateral force applied to an input device and estimating a change in magnitude of the applied lateral force. The method also generates a control signal based on the estimated change in magnitude of the applied lateral force, wherein the control signal is indicative of a change in position of a navigational object on a graphical display. 
     Certain embodiments of the invention have other aspects in addition to or in place of those mentioned or obvious from the above. The aspects will become apparent to those skilled in the art from a reading of the following detailed description when taken with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following drawings are provided for purposes of illustration only and merely depict exemplary embodiments of the disclosure. These drawings are provided to facilitate the reader&#39;s understanding of the disclosure and should not be considered limiting of the breadth, scope, or applicability of the disclosure. It should be noted that for clarity and ease of illustration these drawings are not necessarily made to scale. 
         FIG. 1  illustrates an exemplary computing system using an input device according to various embodiments of this invention. 
         FIG. 2  is a system diagram of a modular arrangement of an input device according to various embodiments of this invention. 
         FIG. 3  is a block diagram of forces exerted on an input device according to various embodiments of this invention. 
         FIGS. 4A-4D  are graphs of force and motion parameters of an input device moving form a first point to a second point according to various embodiments of this invention. 
         FIG. 5  is a flow diagram illustrating a process of controlling movement of a graphical object according to various embodiments of this invention. 
         FIG. 6  is a flow diagram illustrating another process of controlling movement of a graphical object according to various embodiments of this invention. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     In the following description of exemplary embodiments, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration specific embodiments in which the invention can be practiced. It is to be understood that other embodiments can be used and structural changes can be made without departing from the scope of the invention. 
     In accordance with various embodiments, a motion-based input device can include one or more force sensors capable of detecting forces acting upon the input device and generating a signal representative of the detected forces. A system can then initiate (e.g., trigger) one or more events based on the signal. 
     As used herein, the term “event” can refer to any function or process performed by a computer system in response to user input. An event need not be a function traditionally initiated by a user using a motion-based input device, but can also include functions initiated by a user using other types of input devices, including keyboards, touch pads, switches, buttons, dials or any other electrical, mechanical and/or optical mechanism that generates input data in response to a user input. A few non-limiting examples of an event can include moving a cursor displayed on a graphical user interface, making a selection indication (e.g., similar to depressing a selection button on a mouse, for example), changing a mode of operation, turning volume up or down, changing channels, paging back and forth in a software application, initiating a startup or wakeup sequence of a receiving device or the input device, and increasing a data collection rate to decrease lag. 
     As used herein, “motion-based input device” can refer to an input device that detects multi-dimensional motion of the input device relative to a surface. Motion-based input devices can utilize a variety of sensors for detecting movement of the input device relative to a surface and generate an input signal indicating information pertaining to the detected movement. Non-limiting examples of motion-based input devices include electro-mechanical mice (also known as “ball mice”), and optical mice. 
       FIG. 1  illustrates a typical environment or system  100  in which a motion-based input device  102  in accordance with one embodiment may be used. The input device  102  can be positioned upon a surface  104  such as a desk or a tabletop. A user can move the input device  102  relative to the surface  104  to generate output signals indicative of the movement of the input device. 
     Note that in  FIG. 1 , the surface  104  is depicted as being flat or substantially flat. However, this is not strictly necessary according to other embodiments. Also note that the surface  104  need not necessarily be situated beneath the input device  102 . For example, the surface  104  may be tilted, situated above the input device  102 , or vertically oriented. Also note that multiple surfaces  104  can be utilized. 
     A receiving device  106  can be adapted to receive input signals generated by the input device  102 . As used herein, the terms “receiving device” and “receiver” include without limitation video game consoles, set-top boxes, televisions, personal computers (whether desktop, laptop, or otherwise), digital video recorders, communications equipment, terminals, and display devices. In accordance with various embodiments, the receiving device  106  can comprise at least one interface adapted to receive the input signals transmitted from the input device  102 . The input device  102  can be physically coupled to the receiving device via one or more communication links (such as via a serial bus cable), or the input device  102  can be adapted to wirelessly communicate with the receiving device  106 . 
     A display device  108  in communication with the receiving device  106  can be adapted to display a navigational object upon its display screen (for example, a pointer, cursor, selector box, or other such indicator). During operation, when the user manipulates the input device  102  relative to the surface  104 , the input signals generated by the input device are received at the receiving device  106  and the navigational object responds according to the user&#39;s input. As used herein, the term “display device” can include any type of device adapted to display information, including without limitation cathode ray tube displays (CRTs), liquid crystal displays (LCDs), thin film transistor displays (TFTs), digital light processor displays (DLPs), plasma displays, light emitting diodes (LEDs) or diode arrays, incandescent devices, and fluorescent devices. Display devices may also include less dynamic devices such as printers, e-ink devices, and other similar structures. 
       FIG. 2  is a system diagram of a modular arrangement of the input device  102  according to one embodiment of the present invention. The input device  102  includes a printed circuit board  204  comprising electrical leads that enable various modules to communicate with other coupled modules. 
     A power supply  206  provides a source of power to modules electrically coupled to the printed circuit board  204 . In some embodiments, power is supplied externally from one or more conductive wires, for example, through the use of a power cable or a serial bus cable. In other embodiments, a battery may be used as a source of power. 
     A memory  212  comprises any type of module adapted to enable digital information to be stored, retained, and retrieved. Additionally, the memory  212  may comprise any combination of volatile and non-volatile storage devices, including without limitation RAM, DRAM, SRAM, ROM, and/or flash memory. Note also that the memory  212  may be organized in any number of architectural configurations by the use of registers, memory caches, data buffers, main memory, mass storage, and/or removable media, for example. 
     One or more processors  208  can be adapted to execute sequences of instructions by loading and storing data to the memory  212 . Possible instructions include, without limitation, instructions for data conversions, formatting operations, communication instructions, and/or storage and retrieval operations. Additionally, the processors  208  may comprise any type of digital processing devices including, for example, reduced instruction set computer processors, general-purpose processors, microprocessors, digital signal processors, gate arrays, programmable logic devices, reconfigurable compute fabrics, array processors, and/or application-specific integrated circuits. Note also that the processors  208  may be contained on a single unitary integrated circuit (IC) die or distributed across multiple components. 
     Interface module  216  enables data to be transmitted and/or received over one or more communication networks. The data can be transmitted or received wirelessly or through the use of wires. In one embodiment, data transmitted to a receiving device is first packetized and processed according to one or more standardized network protocols. In one embodiment, the interface module  216  comprises a plurality of network layers such that each layer provides services to the layer above it and receives services from the layer below it. The interface module  216  may accommodate any wired or wireless protocol including, without limitation, USB, FireWire, Ethernet, Gigabit Ethernet, MoCA, radio frequency tuners, modems, WiFi, Blutooth, WiMax, and/or Infrared Data Association. 
     A motion detection module  220  comprises sensors and logic adapted to detect and/or measure motion parameters, such as acceleration, speed, velocity and/or position of the input device  102  at a specific instant in time, or alternatively, over a period of time. In accordance with various embodiments, the motion detection sensors can be an optical sensor, an electro-mechanical sensor, or any other sensor used in a motion-based input device capable of detecting motion of the input device  102 . 
     A force detection module  222  can include sensors and logic adapted to detect forces acting upon the input device  102  during an instant in time, or alternatively, over a period of time. In accordance with some embodiments, the force detection module can include one or more force detection sensors operable to detect external forces acting upon the input device  102 . In some embodiments, the force detection module  220  can detect forces acting upon the input device  102  in one dimension (e.g., an x-dimension), in other embodiments the force detection module  222  can sense forces acting upon the input device  102  in two dimensions (e.g., x and y dimensions), and in further embodiments the force detection module  222  can detect forces acting upon the input device  102  in three dimensions (e.g., x, y and z dimensions). 
     As mentioned above, the input device  102  can include one or more force sensors. In some embodiments, a three-component force sensor can detect the forces exerted on the input device in three dimensions (e.g., x, y and z dimensions). Suitable three-component force sensors include Kistler 3-Component Force Sensors, models 9167A, 9168A, 916AB, or 9168AB, offered by Kistler North America located in Amherst, N.Y., USA. In other embodiments, separate force sensors can be used to detect the forces exerted on the input device  102 . 
     In accordance with one embodiment, directions and magnitudes of forces acting upon the input device  102  can be derived from information generated by the force sensors.  FIG. 3  is a block diagram indicating a force F total  applied to the input device  102  positioned on surface  104 . As an example, the force F total  may be applied to the input device  102  by a user to move the input device in a desired direction in a plane of motion. As used herein, a “plane of motion” can be defined as an x-y plane in a Cartesian coordinate system in which a user moves the input device  102 . The x-y plane has an x-axis and a y-axis perpendicular to the x-axis. A z-axis extends perpendicularly from the x-y plane. In one embodiment, the x-y plane is parallel to the surface  104 . 
     As depicted in  FIG. 3 , the force F total  applied to the input device can comprise a lateral force component and a normal force component (the normal force can also be referred to as a vertical force). The lateral force component further includes a first lateral force component, Fx, in a direction along the x-axis, and a second lateral force, Fy, component in a direction along the y-axis. The normal force component, Fz, is in a direction along the z-axis. 
     The direction of the lateral force is mathematically related to the lateral force components, Fx and Fy, applied to the input device  102  in the plane of motion. This relationship can be expressed as:
 
| F |=√{square root over (( Fx   2   +Fy   2 ))}  (1)
 
Where |F| is a total magnitude of the lateral force applied to the input device  102 . Corresponding directional vectors can then be derived using the following expression:
 
 X  direction= Fx/|F|, Y  direction= Fy/|F|   (2)
 
Thus, using the lateral force components, Fx and Fy, applied to the input device  102 , logic residing in force detection module  220  or computer  106 , for example, can estimate a total magnitude of the lateral force and corresponding directional unit vectors of the applied lateral force. Of course, other standard techniques known in physics may be used to calculate a scalar quantity of force from a given set of force vectors. In accordance with various embodiments, the logic may be implemented as any combination of software, firmware and/or hardware.
 
     Note that in one embodiment, motion and force information can be written to a local memory source (not shown) (such as a register or local cache) before being provided as input. In other embodiments, this data can be directly written and retrieved from memory  212 . In still other embodiments, this data can be stored in external memory (e.g. a hard drive of the computer  106 ) and the input device  102  can transmit raw data to the computer  106  for processing. 
     As mentioned above, one or more force sensors  222  can be utilized to generate force information pertaining to forces acting upon the input device  102 . In accordance with one embodiment, the input device  102  can detect lateral components of forces applied to the input device  102  in two directions in a plane of motion of the input device; the first direction being substantially perpendicular to the second direction. Information relating to the detected lateral force components can then be used to calculate an estimated magnitude and direction of a lateral force acting upon the input device  102 , among other things. A system in accordance with various embodiments can then move a navigational object based on the estimated magnitude and direction, for example. 
       FIGS. 4A-4D  are graphs of force, acceleration, velocity and displacement, respectively, versus time of an exemplary movement of input device  102  moving in a straight line from a first point A to a second point B. Furthermore,  FIGS. 4A-4D  illustrate exemplary first through fifth states  401 - 405 , respectively, of the input device  102  while it moves from point A to point B. For illustrative purposes, the following description of  FIGS. 4A-4D  may refer to elements mentioned above in connection with  FIGS. 1-3 . 
     With particular reference to  FIG. 4A , during the first state  401 , a force is applied to input device  102 , for example by a user, but the applied force does not exceed the static (maximum) frictional force between input device  102  and surface  104 . Consequently, in the first state  401 , input device  102  is not yet moving (see  FIGS. 4C and 4D ) despite a force being applied to the input device  102 . 
     During the second state  402 , the applied force exceeds the static frictional force, which results in movement of the input device  102 , as illustrated in  FIGS. 4A and 4D , for example. Note that in accordance with known principles of physics, the coefficient for static frictional force is typically larger than the coefficient for kinetic frictional force. As a consequence, the frictional force between the input device  102  and surface  104  typically decreases once the input device  102  begins sliding on surface  104 . Hence, as depicted in  FIG. 4A , the frictional force decreases at the transition between the first state  401  and the second state  402 . This transition from static friction to kinetic friction can result in unstable control of the input device  102  due to what is commonly referred to as a “stick-slip” phenomenon. This phenomenon is due to a user needing to apply a force that exceeds the static friction to initiate sliding on the input device  102 , which can feel like the input device  102  is “sticking” to surface  104 . But once the static frictional force is exceeded, the smaller kinetic coefficient applies to the frictional force, which can cause a slip or jerk type motion due to the reduction in frictional force. This “stick-slip” phenomenon can make it difficult for a user to control an input device  102  when moving the input device a small distance, for example. 
     During the third state  403 , the applied force is equal to the frictional force. This results in no acceleration ( FIG. 4B ) and a constant velocity ( FIG. 4C ) of the input device  102  along the plane of motion. 
     During the fourth state  4 , the magnitude of the applied force is less than the frictional force. This results in a deceleration of the input device  102  ( FIG. 4B ). 
     Finally, during the fifth state  405 , the input device  102  is stopped. In this state, the applied force no longer exceeds the static frictional force ( FIG. 4A ), and there is no motion (zero velocity) ( FIG. 4C ), no acceleration ( FIG. 4B ), and no change in displacement ( FIG. 4D ). Note that the transition between the fourth state  404  and the fifth state  405  can also result in unstable movement of the input device  102  due to the transition from kinetic friction to static friction. 
     In accordance with various embodiments, a system incorporating input device  102 , such as the system  100  depicted in  FIG. 1 , for example, can determine which state  401 - 405  (e.g., moving or not moving) the input device  102  is in at a given time period by measuring one or more of the parameters described in  FIGS. 4A-4D . Using these parameters, the system  100  determines which state the input device  102  is in and performs different actions (also referred to herein as “initiating events”) depending upon the particular state. For example, while in the first and fifth states  401  and  405 , a system may initiate a fine control mode where a navigational object is moved in relatively small increments (e.g., a relatively small number of pixels); whereas, while in states  402 ,  403  and  404 , the system may initiate a coarse control mode where the navigational object is moved in relatively large increments (e.g., a larger number of pixels than in the fine control mode). Furthermore, in some embodiments, if input device  102  is in the first state  401 , the detected lateral force information can be used to provide an early indication about an impending motion. The impending motion can be determined by using force information generated by the force sensors to estimate a direction of the applied force using expressions (1) and (2), for example. In another embodiment, if input device  102  is in the first state  401 , a system incorporating the input device  102  can prepare the system for an impending motion of the input device  102  by waking components of the system from a sleep mode and/or increasing a data collection rate. 
       FIG. 5  is a flow diagram illustrating an exemplary process  500  of controlling the movement of a navigational object in two modes: a fine control mode and a coarse control mode. The various tasks performed in connection with process  500  may be performed by hardware, software, firmware, or any combination thereof. It should be appreciated that process  500  may include any number of additional or alternative tasks. The tasks shown in  FIG. 5  need not be performed in the illustrated order, and process  500  may be incorporated into a more comprehensive procedure or process having additional functionality not described in detail herein. For illustrative purposes, the following description of process  500  may refer to elements mentioned above in connection with  FIGS. 1-4 . 
     Process  500  begins by detecting lateral force components applied to the input device  102  (e.g., the Fx and Fy force components) and detecting motion of the input device  102  relative to surface  104 , in step  502 . In some embodiments, the motion is detected by one or more accelerometers, vibration sensors, optical sensors, electro-mechanical sensors, some other sensor operable to detect motion of the input device  102 , or a combination thereof. 
     Further to step  502 , process  500  can periodically detect the applied lateral forces and motion. In some embodiments, the lateral forces and motion may be measured every 8 milliseconds, but other lengths of time may be used. In addition, in some embodiments, the length of time between measurements for the lateral force and the motion need not be the same, and, moreover, the lateral force and the motion need not be measured at the same time, but instead can be measured successively. 
     In step  504 , process  500  determines if the input device  102  is moving with respect to the surface  104  by analyzing the motion detected in step  502 . Process  500  can then determine the input device  102  is moving relative to the surface  104  if the velocity is non-zero. Of course other methods of determining if the input device  102  is moving relative to the surface  104  can be used depending upon the motion parameters detected by the input device  102 , as would be apparent to one skilled in the art after reading this disclosure. 
     If the input device  102  is moving relative to the surface  104 , then a coarse control mode is initiated in step  506 . In coarse control mode, an associated navigational object moves in relatively large, coarse increments based on the motion of the input device  102  measured in step  502 . Alternatively, while in coarse control mode, movement of the associated navigational object can be based on the motion of the input device and also in part on the detected lateral forces exerted on the input device. In one embodiment, while in coarse control mode, the input device  102  controls movement of the navigational object in a similar manner as a conventional mouse controls movement of a navigational object. 
     Further to step  506 , in some embodiments, the measured motion includes an acceleration measurement using one or more accelerometers. An estimated speed of input device  102  can then be calculated by integrating the acceleration. Furthermore, an estimated direction of motion can be calculated using the lateral force measurements (step  502 ) using expressions (1) and (2), above. An associated navigational object can then be moved based on the estimated speed and estimated direction of motion. For example, the navigational object can be moved across a graphical user interface in the estimated direction of motion with a speed that is proportional to the estimated speed. In an alternative embodiment, the estimated speed and estimated direction of motion can be used to estimate a change in position of the navigational object. These are merely a few illustrative examples and it is contemplated that other methods of moving a navigational object based on the measured motion of the input device  102  can be used in other embodiments. 
     If the input device is not moving relative to the surface  104  in step  504 , then, in step  508 , magnitudes of the lateral force components, |Fx| and |Fy|, are calculated and compared to force components derived from a prior measurement of the lateral force components. In other words, the magnitudes of successively measured lateral force components are compared to one another in step  508 . Process  500  then determines whether either of the force magnitude |Fx| or |Fy| is increasing as compared to the corresponding previously measured force magnitude in decision step  510 . In accordance with one embodiment, the increasing force criteria of step  510  are considered met when the most recently measured force magnitude (e.g., |Fx t2 | or |Fy t2 | measured at time t 2 ) is greater than the previously measured force magnitude (e.g., |Fx t1 | or |Fy t1 | measured at time t 1 ). 
     If neither of the lateral force magnitudes calculated in step  508  is increasing, then process  500  proceeds to step  512 , where process  500  indicates that no change in position of the navigational object is to occur. In one embodiment, indicating that no change in position is to occur includes setting both a change in x position value, Δx, and a change in y position value, Δy, to zero. 
     On the other hand, if either of the lateral force component magnitudes |Fx| or |Fy| is increasing, then process  500  proceeds to a fine control mode in steps  514  and  516 . In step  514 , a change in position of the navigational object is calculated and a value for the positional change is set in memory, such as memory  212 . In one embodiment, the change in position is calculated using expressions (3) and (4):
 
Δ x =(gain)×(Δ Fx )  (3)
 
Δ y =(gain)×(Δ Fy )  (4)
 
Where Δx and Δy are change in position values of the navigational object along an x-axis and a y-axis, respectively, in a Cartesian coordinate system; gain is a predetermined gain factor; ΔFx is a change in the measured lateral force component along the x-axis; and ΔFy is a change in measured lateral force component along the y-axis. The gain factor can correspond to a desired precision or granularity of moving the navigational object in the fine control mode. In some embodiments, the gain factor has a value corresponding to a total range of 1 to 100 pixels for Δx and Δy. Of course, other values for the gain factor may be used depending upon various factors, such as a desired precision, and the size and resolution of the display upon which the navigational object is displayed and moved.
 
     In alternative embodiments, Δx and Δy are predetermined values. As an example, if the lateral force component measured along the x-axis is increasing in step  510 , then the navigational object is moved in an x-direction by a number of pixels corresponding to the predetermined value of Δx. In this manner, an increasing lateral force imparted on the input device  102  results in the navigational object moving by a predetermined number of pixels. 
     Referring again to  FIG. 5 , once the change in position values, Δx and Δy, are calculated and set in step  514 , the navigational object is moved based on the change in position values, Δx and Δy, in step  516 . 
     In one embodiment, process  500  utilizes two navigational control modes: a coarse control mode when the input device  102  is moving relative to surface  104  and a fine control mode when the input device  102  is not moving relative to surface  104  but a lateral force applied to the input device  102  is increasing. In this manner, a user can move the navigational object a relatively small distance for precise targeting of an area by applying a force to the input device  102  without initiating sliding of the input device relative to the surface  104 . On the other hand, when a user desires to move the navigational object a relatively large distance, for example from one side of a graphical display to another side of a graphical display, then the user can simply slide the input device  102  relative to surface  104  to cause the navigational object to quickly move the larger distance. 
     Process  500  can also prevent or reduce overshooting or undershooting a target area due to the unstable static/kinetic friction transition when transitioning between the first state  401  and the second state  402  and/or the fourth state  404  and the fifth state  405  (see  FIGS. 4A-4D ). For example, once the input device  102  is no longer moving relative to surface  104 , then the process  500  switches to fine control mode, permitting a user to move the navigational object in a precise manner to the target area. 
     Furthermore, in process  500 , the measured lateral force is used to move an associated navigational object in the fine control mode if the measured lateral force is increasing (step  510 ). A reason for step  510  is so that the position of the associated navigational object does not change when the force sensor returns to its “home” or “zero position”. In other words, in operation, a user can move a navigational object by applying a lateral force to the input device  102 . But when the user reduces or stops applying a lateral force to the input device  102 , the force sensor may detect a decrease in the applied lateral force. If the detected decrease in applied lateral force is also used to move the navigational object, then the navigational object could be moved away from a targeted area as a result of the decreasing applied force. This may be undesirable in certain applications. Accordingly, in one embodiment, process  500  does not use a decrease in lateral force to move the associated navigational object. Thus, using process  500 , a user can move the navigational object to a target area by applying a force to the input device  102  and not be concerned about the navigational object moving away from the target area once the user reduces or ceases to apply a force to the input device  102 . However, in alternative embodiments, the navigational object can be moved based on the measured lateral force regardless of whether the measured lateral force is increasing or decreasing, since doing so may be advantageous in some applications. 
     In some embodiments, the transition between the two navigational modes need not be abrupt, but instead can be smooth and seamless. A mathematical formula can be used such that the fine control is dominant initially, e.g., when a user first applies a force to move the input device  102 , and then the coarse control can gradually become dominant as the input device accelerates, for example. 
       FIG. 6  is a flow diagram illustrating a further exemplary process  600  of controlling the movement of a navigational object based on both the measured lateral force and measured motion of the input device  102 , regardless of whether or not the input device is moving relative to the surface  104 . The various tasks performed in connection with process  600  may be performed by hardware, software, firmware, or any combination thereof. It should be appreciated that process  600  may include any number of additional or alternative tasks. The tasks shown in  FIG. 6  need not be performed in the illustrated order, and process  600  may be incorporated into a more comprehensive procedure or process having additional functionality not described in detail herein. For illustrative purposes, the following description of process  600  may refer to elements mentioned above in connection with  FIGS. 1-4 . 
     Process  600  measures the lateral force components applied to the input device  102  and the motion of the input device relative to surface  104  in step  602 . In one embodiment, step  602  can be performed in a similar manner as described above with respect to step  502  of process  500 . 
     Process  600  then calculates change in position values of the navigational object, Δx and Δy, based on both the measured force and measured motion in step  602 . As an example, equations (5) and (6), below, can be used to calculate the values Δx and Δy:
 
Δ x=ΔFx (gain force )+ m   x (gain movement )  (5)
 
Δ y=ΔFy (gain force )+ m   y (gain movement )  (6)
 
Where Δx and Δy are a change in position of the navigational object along an x-axis and y-axis, respectively, of a Cartesian coordinate system; ΔFx and ΔFy are changes in measured lateral force components along the x-axis and y-axis of the plane of motion, respectively; m x  and m y  are estimated movements of the input device  102  along the x- and y-axis of the plane of motion, respectively; gain force  is a predetermined gain factor value corresponding to a desired granularity of moving the navigational object based on lateral force applied to the input device  102 ; and gain movement  is a predetermined gain factor value corresponding to a desired granularity of moving the navigational object based on the movement of the input device  102 . The estimated movements, m x  and m y , can be an estimated speed, acceleration, change in position or other parameter pertaining to the motion of the input device  102  relative to the surface  104 .
 
     It is understood that other equations or mathematical relationships may be used in place of equations (5) and (6). For example, quadratic and/or exponential mathematical relationships may be used to calculate change in position values based on measured force and motion. 
     Similar to process  500 , in process  600 , the value of ΔFx or ΔFy is non-zero when the lateral force applied along the x-axis or y-axis is increasing. Otherwise, the value for ΔFx or ΔFy is zero, thereby resulting in no lateral force contribution to the change in position of the navigational object as set forth in equations (5) and (6). However, other embodiments may use a non-zero value for the change in lateral force, ΔFx or ΔFy, regardless of whether the lateral force is increasing or decreasing. Furthermore, in some embodiments, the value of the change in lateral force components, ΔFx or ΔFy, can be negative or positive, thereby possibly providing a negative or positive contribution to equations (5) or (6), for example. 
     In accordance with one embodiment, values for gain force  and gain movement  are selected to provide smooth and seamless transitions between the first state  401  and the second state  402  and/or the fourth state  404  and the fifth state  405  ( FIGS. 4A-4D ). Furthermore, the values for gain force  and gain movement  need not be constant. For example, mathematical formulas can be used to calculate variable force gain values and variable movement gain values based on various factors, such as a state of the input device  102  (e.g. first-fifth states  401 - 405 , respectively) or other desired parameters. 
     In step  606 , the navigational object is moved based on the values of Δx and Δy. 
     It can be noted that various functions described in processes  500  and  600  can be performed by the input device  102 , the receiving device  106  or by a combination of the two devices. For example, in accordance with one embodiment, after sensors of the input device  102  detect the lateral force and motion (e.g., step  502  or step  602  in process  500  or  600 , respectively), the input device  102  may generate and transmit one or more signals to the receiving device  106  indicative of the detected lateral force and motion. The receiving device  106  can then calculate the values of Δx and Δy based on the one or more signals indicative of the detected lateral force and motion. In such an embodiment, the input device  102  need not have a processor, such as processor  208  depicted in  FIG. 2 . In other embodiments, however, the input device  102  may calculate the values of Δx and Δy using processor  208  ( FIG. 2 ), generate one or more signals indicative of the values of Δx and Δy, and transmit the one or more signals to the receiving device  106 . 
     While this invention has been described in terms of several exemplary embodiments, there many possible alterations, permutations, and equivalents of these exemplary embodiments. For example, the term “computer” does not necessarily mean any particular kind of device, combination of hardware and/or software, nor should it be considered restricted to either a multi purpose or single purpose device. 
     It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents. In addition, as used herein, the terms “computer program” and “software” can refer to any sequence of human or machine cognizable steps that are adapted to be processed by a computer. Such may be rendered in any programming language or environment including, for example, C/C++, Fortran, COBOL, PASCAL, Perl, Prolog, assembly language, scripting languages, markup languages (e.g., HTML, SGML, XML, VOXML), functional languages (e.g., APL, Erlang, Haskell, Lisp, ML, F# and Scheme), as well as object-oriented environments such as the Common Object Request Broker Architecture (CORBA), Java™ (including J2ME, Java Beans, etc.). 
     Moreover, terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as mean “including, without limitation” or the like; the term “example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. Likewise, a group of items linked with the conjunction “and” should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as “and/or” unless expressly stated otherwise. Similarly, a group of items linked with the conjunction “or” should not be read as requiring mutual exclusivity among that group, but rather should also be read as “and/or” unless expressly stated otherwise. Furthermore, although items, elements or components of the invention may be described or claimed in the singular, the plural is contemplated to be within the scope thereof unless limitation to the singular is explicitly stated. The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent. The use of the term “module” does not imply that the components or functionality described or claimed as part of the module are all configured in a common package. Indeed, any or all of the various components of a module, whether control logic or other components, can be combined in a single package or separately maintained and can further be distributed across multiple locations.