Patent Publication Number: US-2021161245-A1

Title: Pressure Sensor to Quantify Work

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/508,860, filed Jul. 11, 2019, which is a continuation of U.S. patent application Ser. No. 14/641,663 titled “Pressure Sensor to Quantify Work” filed on Mar. 9, 2015, now U.S. Pat. No. 10,433,612, which claims priority to U.S. provisional Patent Application No. 61/950,606 titled “Pressure Sensor to Quantify Work” filed Mar. 10, 2014. These applications are herein incorporated by reference for all that they disclose. 
    
    
     BACKGROUND 
     To propel a bicycle, a user sits on a seat and straddles a frame with his or her legs. A pair of pedals are connected to each other with a pair of crank arms that are connected to a gear assembly. The pedals are positioned to be engaged by the feet and to travel in a reciprocating motion powered by the user&#39;s feet. The gear assembly directs the energy exerted through the user&#39;s feet to an axle of one of the wheels of the bicycle, which causes the wheel to turn. Such rotation of the wheel propels the bicycle forward. The speed at which the bicycle travels is dependent on the amount of resistance on the bicycle and the amount of energy that the user exerts with his or her legs to rotate the wheel. The resistance on the bicycle generally includes the collective weight of the bicycle and the user as well as the slope of the terrain on which the bicycle is being propelled. In the case of a stationary bicycle, the resistance may be provided with a magnetic resistance mechanism, a pneumatic resistance mechanism, a hydraulic resistance mechanism, a gear type resistance mechanism, braking pads, tensioning elements, fan blades, another type of resistance mechanism, or combinations thereof. 
     One mechanism for measuring the amount of energy exerted by the user is disclosed in U.S. Patent Publication No. 2003/0074985 issued to Gordon Liao. In this reference, a sensor of the pedaling force of a power-assisting bike includes a transmission system provided with at least one pair of screw gears. One of the screw gears is activated by the pedaling force to rotate at an original location and the other driven by a screw gear engaging to rotate and shift along a shaft, with a resilience member fitted at an end side. An annular magnet is fitted around the end of the shaft of the resilience member and the screw gear, capable to shift together with the screw gear. A Hall sensor is provided on a fixed side of the annular magnet. Thus, the lateral force produced by the screw gears can detect an axially shifting distance of the screw gear and give out a voltage signal to control a motor to output motive power for the bike. Another type of mechanism for measuring the amount of energy exerted by the user is described in U.S. Pat. No. 8,011,242 issued to George David O&#39;Neill. Each of these references are herein incorporated by reference for all that they disclose. 
     SUMMARY 
     In a preferred embodiment of the invention, a monitoring system includes a shoe and a sole integrated into the shoe. The monitoring system also includes a connection mechanism attached to an underside of the sole and is shaped to connect the sole to a pedal. A pressure sensor is incorporated into the shoe that senses a force exerted on the pedal when the shoe is connected to the pedal through the connection mechanism. 
     In one aspect of the invention, the pressure sensor distinguishes between upward forces and downward forces. 
     In one aspect of the invention, the shoe also comprises an accelerometer that senses a direction of the force exerted on the pedal. 
     In one aspect of the invention, the shoe also comprises a wireless transmitter that transmits measurements of the pressure sensor to a computing device. 
     In one aspect of the invention, the computing device comprises a processor and memory with programmed instructions where the programmed instructions cause the processor to quantify the force based at least in part on the measurements of the pressure sensor. 
     In one aspect of the invention, the programmed instructions further cause the processor to quantify a calorie count based at least in part on the measurements of the pressure sensor. 
     In one aspect of the invention, the connection mechanism is a clipless pedal system. 
     In one aspect of the invention, the pressure sensor is positioned proximate a cleat receptacle of the clipless pedal system. 
     In one aspect of the invention, the pressure sensor is a capacitive based pressure sensor. 
     In one aspect of the invention, the capacitive based pressure sensor comprises electrically conducting plates that are spaced a distance from each other, wherein the electrically conducting plates move such that the distance narrows during a downward force and the distance widens during an upward force. 
     In one aspect of the invention, the shoe further comprises an energy harvesting mechanism that converts a motion of the shoe into electrical power when the shoe is in motion. 
     In one aspect of the invention, the shoe further comprises an energy harvesting mechanism that converts a pressure exerted onto the sole into electrical power. 
     In one aspect of the invention, a monitoring system may include a shoe. 
     In one aspect of the invention, a sole integrated into the shoe. 
     In one aspect of the invention, a clipless pedal system that connects the sole to a pedal when the pedal is attached to the clipless pedal system. 
     In one aspect of the invention, a pressure sensor incorporated into the shoe and positioned proximate a cleat receptacle of the clipless pedal system. 
     In one aspect of the invention, the pressure sensor senses a force exerted on the pedal. 
     In one aspect of the invention, the pressure sensor distinguishes between upward forces and downward forces. 
     In one aspect of the invention, the shoe further comprises an energy harvesting mechanism that supplies the pressure sensor with electrical power. 
     In one aspect of the invention, the shoe also comprises an accelerometer that that senses a direction of the force exerted on the pedal. 
     In one aspect of the invention, the shoe also comprises a wireless transmitter that transmits measurements of the pressure sensor to a computing device. 
     In one aspect of the invention, the computing device comprises a processor and memory with programmed instructions that cause the processor to quantify the force based at least in part on the measurements of the pressure sensor. 
     In one aspect of the invention, the programmed instructions further cause the processor to quantify a calorie count based at least in part on the measurements of the pressure sensor. 
     In one aspect of the invention, the pressure sensor is a capacitive based pressure sensor. 
     In one aspect of the invention, the capacitive based pressure sensor comprises electrically conducting plates that are spaced a distance from each other, wherein the electrically conducting plates move such that the distance narrows during a downward force to the pedal and the distance widens during an upward force to the pedal. 
     In one aspect of the invention, a monitoring system may comprise a shoe. 
     In one aspect of the invention, a sole integrated into the shoe. 
     In one aspect of the invention, a clipless pedal system that connects the sole to a pedal when the pedal is attached to the clipless pedal system. 
     In one aspect of the invention, a capacitive based pressure sensor incorporated into the shoe and positioned proximate a cleat receptacle of the clipless pedal system. 
     In one aspect of the invention, the capacitive based pressure sensor that senses a force exerted on the pedal wherein the capacitive based pressure sensor distinguishes between upward forces to the pedal through the shoe and downward forces to the pedal through the shoe. 
     In one aspect of the invention, the shoe further comprises an energy harvesting mechanism that supplies the capacitive based pressure sensor with electrical power. 
     In one aspect of the invention, an accelerometer incorporated into the shoe that senses a direction of the force exerted on the pedal. 
     In one aspect of the invention, the capacitive based pressure sensor comprises electrically conducting plates that are spaced a distance from each other, wherein the electrically conducting plates move such that the distance narrows during a downward force on the pedal and the distance widens during an upward force to the pedal. 
     In one aspect of the invention, a wireless transmitter incorporated into the shoe that transmits measurements of the capacitive based pressure sensor to a computing device. 
     In one aspect of the invention, the computing device comprises a processor and memory with programmed instructions. 
     In one aspect of the invention, the programmed instructions cause the processor to quantify the force based at least in part on the measurements of the capacitive based pressure sensor. 
     In one aspect of the invention, the programmed instructions cause the processor to quantify a calorie count based at least in part on the measurements of the capacitive based pressure sensor. 
     Any of the aspects of the invention detailed above may be combined with any other aspect of the invention detailed herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate various embodiments of the present apparatus and are a part of the specification. The illustrated embodiments are merely examples of the present apparatus and do not limit the scope thereof. 
         FIG. 1  illustrates a perspective view of an example of a stationary bike in accordance with the present disclosure. 
         FIG. 2  illustrates a perspective view of an example of a shoe in accordance with the present disclosure. 
         FIG. 3  illustrates a diagram of an example of a pressure sensor in accordance with the present disclosure. 
         FIG. 4  illustrates a diagram of an example of a pressure sensor in accordance with the present disclosure. 
         FIG. 5  illustrates a block diagram of an example of a monitoring system in accordance with the present disclosure. 
         FIG. 6  illustrates a cross sectional view of an example of an energy harvesting mechanism in accordance with the present disclosure. 
         FIG. 7  illustrates a cross sectional view of an example of an energy harvesting mechanism in accordance with the present disclosure. 
         FIG. 8  illustrates a cross sectional view of an example of a monitoring system in accordance with the present disclosure. 
     
    
    
     Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements. 
     DETAILED DESCRIPTION 
     Clipless bicycle pedals allow a rigid attachment to be made between a user&#39;s shoe and the pedal. Often, clipless bicycle pedals are used in lieu of straps that hold the user&#39;s shoe to the pedal as the user pulls up, thus keeping the shoe and the pedal together. These straps that are attached to the pedals stretch as the shoe is raised. As a result, some of the energy exerted by the user to pull up on the pedal through the strap is lost. Further, there is often a gap between the underside of the strap and the top of the user&#39;s shoe. Thus, to pull up on the strap with the shoe, the shoe may have be lifted off of the pedal to make contact with the strap&#39;s underside. The effort exerted to lift the shoe to the underside of the strap also does not contribute to the movement of the pedals. As a result, more energy is lost in the system. The clipless pedals are constructed to minimize such inefficiencies. 
     Often, the clipless pedals attach to a specialized shoe that can be locked to the pedal. In some cases, the shoe includes a cleat receptacle that can receive a cleat secured to the pedal. The cleats are often attached to the pedal with one or more bolts. Some shoes with cleat receptacles lock onto the cleat when the user steps firmly onto the pedal in a vertical direction, and the shoe unlocks when the user twists his or her heel outward. Often, the shoes associated with the clipless pedals have rigid soles to maximize efficiency and transfer power to the pedals. 
     The principles described in the present disclosure include a monitoring system that can measure the amount of work performed by a user on a bicycle. Such a system may be used for bicycles that can be propelled by the user&#39;s work, such as a road bicycle or a mountain bicycle. Also, the monitoring system may be incorporated into a stationary bicycle. The monitoring system includes a shoe with a sole that has an underside shaped to attach to a connection mechanism, such as a cleat of a pedal associated with a clipless pedal system. A pressure sensor is also incorporated into the shoe and senses a force exerted on the pedal. In some instances, the pressure sensor senses both upward forces and downward forces exerted by the user. An accelerometer can be used to determine the direction of the force. But, in some examples, the arrangement of the pressure sensor can distinguish between upward forces and downward forces without the assistance of an accelerometer. 
     The shoe can be in wireless communication with a mobile device or a control module of the stationary bicycle. The values measured with the pressure sensor can be sent to such remote devices where calculations about the amount of work performed by the user are calculated. Such calculations may be used to determine a number of calories burned by the user. 
     The energy to power the pressure sensor, accelerometer, transmitter, and other components of the monitoring system that are in the shoe can be harvested from the work performed by the user. For example, the power can be harvested through a piezoelectric system, a kinetic capture system, another type of system, or combinations thereof. In some examples, the energy levels performed by the components of the monitoring system are kept low so that enough power can be provided through energy harvesting. 
     For the purposes of this disclosure, terms such as “upward” are used with reference to motions where the pedal is moving in a direction towards the user&#39;s knee. Likewise, for the purposes of this disclosure, terms such as “downward” are used with reference to motions where the pedal is moving in a direction away from the user&#39;s knee. 
     Further, for the purposes of this disclosure, the term “connection mechanism” includes a structure on the underside of the shoe that assists in connecting the shoe to the pedal. Such connection mechanisms can include fittings for bicycle cleats, other attachment fittings, cleats, other mechanism, or combinations thereof. 
     Particularly, with reference to the figures,  FIG. 1  illustrates a perspective view of an example of a stationary bicycle  10  in accordance with the present disclosure. In this example, the user is wearing a shoe  12  that includes a pressure sensor that is in wireless communication with a remote device  14 . The pressure sensor collects information about the work performed by the user during the workout. The remote device  14  can use the information sent from the shoe  12  to determine results about the user&#39;s workout, like calories burned, distance traveled, speed, and other types of information. The calculated results can be presented to the user in real time, such as in a display of the stationary bicycle  10 . In some examples, the information and/or the calculated results are updated to a database where the user can retrieve them at a later time. 
     The measurements collected by the shoe  12  can be sent to the remote device  14  in raw form where the data can be processed. In some examples, some data processing occurs prior to the information being sent to the remote device  14 . Such data processing may lower the transmission time or lower the transmission power when transmitting data from the shoe  12  to the remote device  14 . 
     In some embodiments, the shoe  12  takes just pressure measurements. However, in some cases the shoe  12  may also include an accelerometer, another type of sensor, or combinations thereof. The measurements from the accelerometer or other sensors may be sent to the remote device  14  with the measurements from the pressure sensor. Information collected by the accelerometer may be used to improve the pressure sensor calculations. The accelerometer can detect movement of the shoe  12 , the direction of the movement, the speed of the movement, and other types of information about the movement that may allow the shoe  12 , the remote device  14 , or other device to correct for motion artifacts exhibited in the pressure measurements. 
     The remote device  14  may be part of a mobile device that can perform calculations to determine the amount of work exerted by the user. However, in other examples, the remote device  14  is incorporated into a stationary bicycle  10 . Any appropriate type of stationary bicycle  10  may be used in accordance with the principles described in the present disclosure. For example, the stationary bicycle  10  may include a magnetic resistance mechanism, a pneumatic resistance mechanism, a hydraulic resistance mechanism, a gear type resistance mechanism, a pair of braking pads, a tensioning element, a fan blade, another type of resistance mechanism, or combinations thereof. While the examples above have been described with reference to bicycles, the principles described herein may be incorporated into other types of exercise or recreational equipment. For example, the principles described herein may be incorporated into elliptical exercise machines, paddle boats, unicycles, tricycles, stepper machines, other types of foot operated devices, or combinations thereof. 
       FIG. 2  illustrates a perspective view of a shoe  12  in accordance with the present disclosure. In this example, the shoe  12  is connected to a pedal  16  through a connection mechanism  18  that is incorporated into a clipless pedal system  20 . A pressure sensor  22  and an accelerometer  24  are also incorporated into the shoe  12  and record information while the shoe  12  is secured to the pedal  16  through the clipless pedal system  20 . 
     Any appropriate type of shoe  12  may be used in accordance with the principles described herein. In some examples, the shoe  12  is a cycling shoe  12  that has a sole  26  made of a stiff material to minimize flexing of the sole  26  as a force is transferred from the shoe  12  to the pedal  16 . The clipless pedal system  20  includes a cleat receptacle in the sole  26  of the shoe  12 . The cleat  27  protrudes upward from the pedal and is shaped to interlock with cleat receptacle of the shoe  12  In some examples, the cleat snaps into a spring loaded mechanism incorporated into the sole  26  of the shoe  12 . The cleat may be made of any appropriate material, such as metal, plastic, or other types of material. Further, the cleat may have any appropriate type of shape to interlock with the shoe&#39;s sole  26 . 
     Any appropriate type of pedal  16  may be used with the shoe  12  in accordance with the principles described in the present disclosure as long as the pedal  16  is capable of interlocking with the shoe  12  through the connection mechanism  18 , in some examples, the pedal  16  can interlock with the shoe  12  on both faces of the pedal, while in other examples, the pedal  16  can interlock with just a single face of the shoe  12 . 
     In the example of  FIG. 2 , the pressure sensor  22  is positioned above the cleat and comprises a first plate  28  and a second plate  30 , which are enlarged for illustrative purposes in the figure. The first and second plates  28 ,  30  are part of an electrically conductive circuit. The capacitance of the circuit is, in part, dependent on the distance between the first and the second plates  28 ,  30 . The distance between the plates  28 ,  30  during the pedal&#39;s revolution is based on the amount of pressure applied by the user. For example, as the user applies a downward force with his or her foot, the foot pushes on the shoe  12  from within the shoe. This downward force pushes against the first plate  28  and causes the first plate  28  to move with the shoe  12 . However, the second plate  30  does not move as much as the first plate  28  in response to the downward force. In other words, there is relative movement between the first plate  28  and the second plate  30 , In some examples, the relative movement is caused because second plate  30  is rigidly connected to the pedal  16  through the connection mechanism  18  while the first plate  28  is allowed to move relative to the downward force. In other examples, the sole of the shoe  12  is compressed in response to the downward force causing the first and second plates  28 ,  30  to move closer. 
     The pedal  16  can be connected to the gear assembly of a self-propelling bicycle or to a resistance mechanism of a stationary bicycle  10 , The movement of the pedal in the self-propelling bicycle may be resisted by an incline of the terrain, friction of the terrain, other terrain conditions, the weight of the bicycle, a load on the bicycle, friction in the gear assembly, other conditions, or combinations thereof, Regardless of the source of the resistance to the movement of the pedal  16 , the resistance can cause the second plate  30  to move less than the first plate  28 . The more force exerted by the user, the greater the relative movement between the first and second plates  28 ,  30 . Further, the greater the relative movement of the first and second plates  28 ,  30 , the greater the distance between the first and second plate  28 ,  30 , 
     On the back end of the revolution, the user can pull his or her foot in an upward direction. This type of motion can cause the first and second plates  28 ,  30  to move apart. For example, as the user pulls up, the shoe  12  pulls up with the user&#39;s foot. As the shoe  12  moves in the upward direction due to the forces exerted by the user, the first plate  28  moves upward as well. However, the second plate&#39;s movement is be resisted by the pedal  16 . As a result, the distance between the first plate  28  and the second plate  30  increases. 
     The distance between the plates  28 ,  30  can be recorded based on the capacitance of the circuit. In some examples, the capacitance of the circuit is periodically sampled, and the forces are reconstructed based on the samples. Such samples may be gathered at second intervals, microsecond intervals, intervals spanning multiple seconds, other types of intervals, or combinations thereof. In other examples, a measurement signal of the circuit&#39;s capacitance is continuously monitored. 
     The recorded measurements can be stored temporarily in memory in the shoe  12  and then be transmitted to a remote device  14 . Such memory may include a buffer, a cache, another type of short term memory, or combinations thereof. In such examples, the temporarily stored measurements may be sent to the remote device  14  on a periodic basis that allows the measurements to be obtained by the remote device  14  in real time or near real time. For example, a transmitter of the shoe  12  may send the stored data to the remote device  14  at one second intervals, sub-second intervals, microsecond intervals, other types of intervals, or combinations thereof. In other examples, the measurements may be continuously transmitted to the remote device  14 . 
     The data may be processed prior to sending the data to the remote device  14 . Such data processing may include compression processing or other types of processing that may reduce the transmission time or the transmission power of sending the data to the remote device  14 . In other examples, the signals are not pre-processed prior to sending. The remote device  14  may further process the measurements. 
     In some examples, the remote device  14  calculates the calories burned, the distance traveled, the speed, and other parameters related to the user&#39;s workout based on the pressure measurements. In addition to sending the remote device  14  information from the pressure sensor  22 , some examples include sending measurements from the accelerometer  24 . 
     The accelerometer  24  may be positioned in any appropriate location in the shoe  12 . The accelerometer  24  may sense motion of the shoe  12  in multiple directions, including upward directions, downward directions, and directions to the side. The accelerometer&#39;s measurements may be used to determine if a motion artifact exists in the values collected with the pressure sensor  22 . If such a motion artifact exists, the recorded pressures can be modified to reflect the appropriate values without the motion artifact. The accelerometer&#39;s measurements may be sent to the memory or directly to the transmitter for conveyance to the remote device  14 . In some embodiments, the accelerometer&#39;s measurements stay locally within the shoe  12  and are used to modify the recorded pressures prior to sending them to the remote device  14 . In other examples, the calculations and other adjustments to be made based on the measurements from the accelerometer  24  are performed at the remote device  14 . In other examples, the accelerometer  24  is used to determine the direction of the force applied to the shoe  12 . 
     In some examples, the other information is recorded by other sensors in the shoe  12  or outside of the shoe  12 . Such additional measurements may also be sent to the remote device  14 . For example, a heart rate monitor  56 , an oxygen consumption monitor, a blood pressure monitor, an odometer  58 , a speedometer  60 , a timer  55 , a resistance mechanism  54 , another type of sensor, or combinations thereof may send additional information to the remote device  14 . 
     Workout results derived from the information received by the remote device  14  may be presented to the user during his workout in real time or near real time. For example, the calculated information may be displayed in a display of the stationary bicycle  10 . In other examples, the information may be displayed in a display that mounts to the handle bars or another component of the self-propelling bicycle. However, in yet other examples, the remote device  14  does not perform calculations on the obtained information, but rather forwards the information to a cloud based network device where the information is accessible to a remote device  14  that can make calculations based on the data. Such a network device may be part of a database that stores information about the user&#39;s fitness or exercise activities. In other examples, the remote device  14  forwards the information directly to another device that performs the calculations. In some examples, the results of the calculations are sent back to a display associated with the bicycle while the user is still performing the workout for providing feedback to the user. 
     Any appropriate type of communication protocol between the shot&#39;s transmitter and the remote device may be used in accordance with the principles described in the present disclosure. Such protocols may include standard wireless protocols, protocols used by Bluetooth® technologies, protocols, Z-wave protocols, Zigbee protocols, other types of wireless protocols, or combinations thereof. 
     In alternative embodiments, the data is stored in the shoe  12  until it is downloaded. In such an example, the stored data may be downloaded after the workout is finished. This allows the user to review his or her results after the workout is concluded, Downloading the data may be accomplished wirelessly. In some examples, a cable can be used to download the data. 
       FIGS. 3 and 4  illustrate a pressure sensor  22  in accordance with the present disclosure. In these examples, both the first plate  28  and the second plate  30  of the pressure sensor  22  are disposed within the shoe  12 . Additionally, the second plate  30  is rigidly attached to the connection mechanism  18 , such as a cleat receptacle. In such examples, when the cleat  27  is interlocked with the cleat receptacle, the second plate  30  is also rigidly attached to the pedal  16 . The first plate  28  moves based on the pressures exerted on the sole  26  of the shoe  12 . Thus, as the foot exerts an upward force on the shoe  12 , the first plate  28  is pulled upwards, which increases the distance  32  between the first plate  28  and the second plate  30 . Likewise, as the foot exerts a downward force on the shoe  12 , the first plate  28  is pushed downwards, which decreases the distance  32  between the first plate  28  and the second plate  30 . 
     In the illustrated example, the first and the second plates  28 ,  30  store an electrical charge as part of a circuit. As the distance  32  between the first plate  28  and the second plate  30  changes, the amount of capacitance that the circuit can hold also changes. These capacitive changes can be detected with a capacitance meter, a volt meter, an ammeter, another type of meter, or combinations thereof. As a result, the circuit can exhibit electrical properties that indicate the distance  32  between the plates  28 ,  30 . Thus, as the pressures exerted by the foot cause the plates  28 ,  30  to move relative to one another, the pressure changes can be sensed by measuring the electrical properties of the circuit. 
     In some examples, the readings of the pressure sensor  22  indicate whether there is an upward force or a downward force on the pedals. In one approach for determining the direction of the pressure forces, a predetermined baseline distance is selected. A baseline distance between the first plate  28  and the second plate  30  is depicted in  FIGS. 3 and 4  with a dashed line  31 , which may represents the resulting distance  32  between the plates  28 ,  30  in the absence of upward or downward forces. In such an example, when there are no forces exerted by the user, the distance  32  between the plates  28 ,  30  are as though the underside of the first plate  28  rests on the dashed line  31 . As a result, when the underside of the first plate  28  is above the dashed line  31 , a processing device may determine that there is an upward force on the pedal  16 . Likewise, when the underside of the first plate  28  is below the dashed line  31 , the processing device may determine that there is a downward force on the pedal  16 . In some examples, an electrical property of circuit can correlate with the distance  32  between the plates  28 ,  30 . Thus, a baseline electrical value may be associated with the baseline distance. As a result, a processor may determine whether the force is an upward force or a downward based on whether the electrical property is above or below the baseline value. Further, the processor may understand the amount of force applied in either the upward or downward direction based on how high or how low the measured electrical property is from the baseline value. 
     In another approach, the processing device may determine that there is an upward force or an downward force by determining whether the distance  32  between the plates is increasing or decreasing. For example, to determine whether a pressure reading associated with a first timestamp is an upward force or a downward force, the processing device may look at a set of distances taken immediately before and/or immediately after the timestamp to determine whether the distances between the plates  28 ,  30  are increasing or decreasing. If the distance  32  between the plates is increasing, then the processing element may determine that there is an upward force. On the other hand, if the distance  32  between the plates is decreasing, then the processing element may determine that the force is a downward force. As described above, the distance may correspond to an electrical property of the circuit. Thus, in some examples, the direction of the force may be determined by whether the measured electrical property is increasing or decreasing. 
     In yet another approach, the accelerometer  24  may take measurements to determine whether the pedal  16  is going in an upward direction or a downward direction. In such an approach, measurements from the accelerometer  24  and the pressure sensor  22  may be compared to determine which direction the pedal  16  is moving and assign a direction to the force based on the direction indicated by the accelerometer  24 . 
     In some examples, a pressure sensor  22  and associated components are incorporated into just a single shoe worn by the user. In such a circumstance, the processing device may estimate the forces exerted by the user&#39;s other foot. In situations where both shoes worn by the user include the pressure sensor  22  and associated components, the measurements for each shoe  12  can be used to determine the calories and forces specific to the foot exerting the energy. In some examples, a display may indicate which calories, forces, or other parameters are attributable to which foot. 
     The processing device may have the capability of determining whether the user is pedaling the bicycle, walking, or performing another task. In such an embodiment, the patterns exhibited in the accelerometer&#39;s readings and/or the pressure sensor&#39;s readings can be analyzed. If it is determined that the user is standing or just walking, the components of the shoe  12  may switch off, discard recorded data, withhold recorded data from the processing device, take another action, or combinations thereof. On the other hand, if the accelerometer&#39;s measurements or the pressure sensor&#39;s measurements exhibit patterns that suggest that the user is pedaling, the processing device may incorporate the measurements into the calculations for determining a calorie count, stroke specific calculations, torque, other determinations, or combinations thereof. In such examples, the user may start and stop his or her workout without turning on or off the shoe&#39;s sensors to avoid integrating non-relevant data into the user&#39;s fitness information. 
       FIG. 5  illustrates a block diagram of an example of a monitoring system  34  in accordance with the present disclosure. The monitoring system  34  may include a combination of hardware and program instructions for executing the functions of the monitoring system  34 . In this example, the monitoring system  34  includes processing resources  36  that are in communication with memory resources  38 . Processing resources  36  include at least one processor and other resources used to process programmed instructions. The memory resources  38  represent generally any memory capable of storing data such as programmed instructions or data structures used by the monitoring system  34 . The programmed instructions shown stored in the memory resources  38  include a pressure determiner  40 , a direction determiner  42 , a resistance level determiner  44 , a stroke specific forces determiner  46 , and a calorie counter  50 . The data structures shown stored in the memory resources  38  include a stroke specific forces library  48 . 
     The memory resources  38  include a computer readable storage medium that contains computer readable program code to cause tasks to be executed by the processing resources  36 . The computer readable storage medium may be a tangible and/or non-transitory storage medium. The computer readable storage medium may be any appropriate storage medium that is not a transmission storage medium. A non-exhaustive list of computer readable storage medium types includes non-volatile memory, volatile memory, random access memory, write only memory, flash memory, electrically erasable program read only memory, magnetic based memory, other types of memory, or combinations thereof. 
     The pressure determiner  40  represents programmed instructions that, when executed, cause the processing resources  36  to determine the amount of pressure exerted on the pedal  16  based on readings from a right pressure sensor  51  and a left pressure sensor  52 . The direction determiner  42  represents programmed instructions that, when executed, cause the processing resources  36  to determine the direction of the pressure exerted on the pedal  16 . The direction of the force may be determined based on the readings from the pressure sensors  51 ,  52 . In some examples, the direction of the pressures is determined, at least in part, with an accelerometer  24 . The resistance level determiner  44  represents programmed instructions that, when executed, cause the processing resources  36  to determine the amount of resistance applied to reciprocating movement of the pedals based on an output from a resistance mechanism  54 . The stroke specific forces determiner  46  represents programmed instructions that, when executed, cause the processing resources  36  to determine forces that are specific to each stroke executed by the user. A non-exhaustive list of stroke specific forces that may be calculated in accordance with the principles described in the present disclosures include torque, revolution speed, calories burned, upward force, downward force, overall force, other types of stroke specific forces, or combinations thereof. These forces may be kept in the stroke specific forces library  48 . The calorie counter  50  represents programmed instructions that, when executed, cause the processing resources  36  to track the number of calories burned by the user. The accelerometer  24  may be used to determine when a stroke is completed. A stroke may be an entire revolution, and the accelerometer  24  may record acceleration patterns throughout the revolution. In some examples, as the patterns recorded by the acceleration patterns repeat, the beginning and ending of a stroke can be determined. A timer  55  can associate the measurements with a point in time to assist in determining the time at which the pressure and/or accelerometer measurements were taken. 
     The calorie counter  50  may use information from the stroke specific library  48 , from the pressure sensors  51 ,  52 , the accelerometer  24 , a heart rate monitor  56  worn by the user, an odometer  58  mounted to the bicycle, a speedometer  60  mounted to the bicycle, other instruments, or combinations thereof. 
     The calculated results of the workout can be presented to the user through any appropriate mechanism. In some examples, the calculated results are displayed to the user through a display  62  mounted to the bicycle or a mobile device of the user. 
     Further, the memory resources  38  may be part of an installation package. In response to installing the installation package, the programmed instructions of the memory resources  38  may be downloaded from the installation package&#39;s source, such as a portable medium, a server, a remote network location, another location, or combinations thereof. Portable memory media that are compatible with the principles described herein include DVDs, CDs, flash memory, portable disks, magnetic disks, optical disks, other forms of portable memory, or combinations thereof. In other examples, the program instructions are already installed. Here, the memory resources  38  can include integrated memory such as a hard drive, a solid state hard drive, or the like. 
     In some examples, the processing resources  36  and the memory resources  38  are located within the shoe  12 . The memory resources  38  may be part of the shoe&#39;s main memory, caches, registers, non-volatile memory, or elsewhere in the shoe&#39;s memory hierarchy. Alternatively, the memory resources  38  may be in communication with the processing resources  36  over a network. Further, the data structures, such as the libraries, may be accessed from a remote location over a network connection while the programmed instructions are located locally. Thus, information from the monitoring system  34  may be accessed from the shoe  12 ; a user device; a mobile device; a phone; an electronic tablet; a wearable computing device; a head mounted device; a server; a collection of servers; a networked device; a watch; a user interface in a car, truck, plane, boat, bus, another type of automobile; or combinations thereof. 
     The monitoring system  34  of  FIG. 5  may be part of a general purpose computer. However, in alternative examples, the monitoring system  34  is part of an application specific integrated circuit. 
       FIG. 6  illustrates a cross sectional view of an example of an energy harvesting mechanism  64  in accordance with the present disclosure. In this example, the energy harvesting mechanism  64  includes a piezoelectric material  66  that exhibits a characteristic of producing a voltage when mechanically deformed. In such an example, the piezoelectric material  66  receives a portion of the load when the user exerts a downward force through the shoe  12 . Under such a load, the voltage is produced, which generates a current. The piezoelectric material  66  is part of a circuit and is oriented to direct the current and/or voltage generated by the deformation of the piezoelectric material  66  towards a power storage unit. 
     In some examples, the power storage unit is a capacitor that stores the electrical energy until the energy is needed. At such a time, the capacitor discharges enough energy to power the operation. In some examples, multiple components of the monitoring system  34  are operated by the electrical energy discharged by the capacitor. For example, electrical energy may be used to write measurements into a memory stored in the shoe  12 , transmit the measurements to the remote device  14 , record an accelerometer reading, write values from the accelerometer reading into memory, process the data recorded by the accelerometer  24  and/or pressure sensor  22 , perform other functions, or combinations thereof. In other examples, chargeable batteries or other types of power storage units are incorporated into the shoe  12  and are the recipients of the electrical energy from the energy harvesting mechanism  64 . 
       FIG. 7  illustrates a cross sectional view of an example of an energy harvesting mechanism  64  in accordance with the present disclosure. In this example, the energy harvesting mechanism  64  includes chamber  68  that is shaped to house a reciprocating magnet  70  that travels in response to the movement of the shoe  12 . Also, an electrically conductive coil  72  is incorporated into the chamber  68 . The electrically conductive coil  72  and the reciprocating magnet  70  are arranged so that as the reciprocating magnet  70  travels in response to the shoe&#39;s movement. As the reciprocating magnet  70  travels, it&#39;s magnetic field passes through portions of the electrically conductive coil  72 , which induces an electrical current. The electrically conductive coil  72  may be incorporated into a circuit that directs the electrical current to the power storage unit, where the stored electrical power can be used for operations of the pressure sensor  22  and other components incorporated into the shoe  12 . 
       FIG. 8  depicts the monitoring system with a shoe  800  and a sole  802  integrated into the shoe  800 . A connection mechanism  804  is attached to an underside of the sole  802  and is shaped to connect the sole  802  to a pedal  808 . A pressure sensor  806  incorporated into the shoe  800  that senses a force exerted on the pedal  808  when the shoe  800  is connected to the pedal  808  through the connection mechanism  804 . 
     INDUSTRIAL APPLICABILITY 
     In general, the invention disclosed herein may provide the user with calorie and force calculations associated with the work performed on a bicycle or another foot operated device. The bicycle may be a stationary bicycle or a self-propelled bicycle. The pressure sensor can be incorporated into the shoe proximate the cleat receptacle of a clipless pedal system or another type of system where the shoe is connected to the pedal. The pressure sensor can include at least two plates that move in response to upward forces and/or downward forces exerted by the user while pedaling. 
     A pressure sensor in accordance with the present disclosure may include a pressure sensor with a first plate and the second plate. In some cases, the second plate is rigidly attached to the connection mechanism, such as a cleat receptacle in the sole of the shoe. In such examples, when the cleat is interlocked with the shoe, the second plate is also rigidly attached to the pedal. The first plate may move based on the pressures exerted on the sole of the shoe. Thus, as the foot exerts an upward force on the shoe, the first plate is pulled upwards, which increases the distance between the first plate and the second plate. Likewise, as the foot exerts a downward force on the shoe, the first plate is pushed downwards, which decreases the distance between the first plate and the second plate. 
     In the some examples, an electrical circuit is incorporated into the shoe. The electrical shoe includes a first and the second plates that store an electrical charge. As the distance between the first plate and the second plate changes, the amount of capacitance that the circuit can hold also changes. These capacitive changes can be detected with a capacitance meter, a volt meter, an ammeter, another type of meter, or combinations thereof. As a result, the circuit can exhibit electrical properties that indicate the distance between the plates. Thus, as the pressures exerted by the foot cause the plates to move relative to one another, the pressure changes can be sensed by measuring the electrical properties of the circuit. 
     In some examples, the pressure sensor may indicate whether there is an upward force or a downward force on the pedals. In one approach for determining the direction of the pressure forces, a predetermined baseline distance is selected. A baseline distance between the first plate and the second plate may represents the resulting distance between the plates in the absence of upward or downward forces cause by the turning of the pedal. In such an example, when there are no such forces exerted by the user to turn the pedal, the distance between the plates are at the baseline distance. As a result, when the underside of the first plate is above the baseline distance, a processing device may determine that there is an upward force on the pedal. Likewise, when the underside of the first plate is below the dashed line, the processing device may determine that there is a downward force on the pedal. In some examples, an electrical property of circuit can correlate with the distance between the plates. Thus, a baseline electrical value may be associated with the baseline distance. As a result, a processor may determine whether the force is an upward force or a downward based on whether the electrical property is above or below the baseline value. Further, the processor may understand the amount of force applied in either the upward or downward direction based on how high or how low the measured electrical property is from the baseline value. 
     In another approach, the processing device may determine that there is an upward force or an downward force by determining whether the distance between the plates is increasing or decreasing. For example, to determine whether a pressure reading associated with a first timestamp is an upward force or a downward force, the processing device may look at a set of distances taken immediately before and/or immediately after the timestamp to determine whether the distances between the plates are increasing or decreasing. If the distance between the plates is increasing, then the processing element may determine that there is an upward force. On the other hand, if the distance between the plates is decreasing, then the processing element may determine that the force is a downward force. In some examples, the distance may correspond to an electrical property of the circuit. Thus, in some examples, the direction of the force may be determined by whether the measured electrical property is increasing or decreasing. 
     In yet another approach, the accelerometer may take measurements to determine whether the pedal is going in an upward direction or a downward direction. In such an approach, measurements from the accelerometer and the pressure sensor may be compared to determine which direction the pedal is moving and assign a direction to the force based on the direction indicated by the accelerometer. 
     In some examples, a pressure sensor and associated components are incorporated into just a single shoe worn by the user. In such a circumstance, the processing device may estimate the forces exerted by the user&#39;s other foot. In situations where both shoes worn by the user include the pressure sensor and associated components, the measurements for each shoe can be used to determine the calories and forces specific to the foot exerting the energy. In some examples, a display may indicate which calories, forces, or other parameters are attributable to which foot. 
     The processing device may have the capability of determining whether the user is pedaling the bicycle, walking, or performing another task. In such an embodiment, the patterns exhibited in the accelerometer&#39;s readings and/or the pressure sensor&#39;s readings can be analyzed. If it is determined that the user is standing or just walking, the components of the shoe may switch off, discard recorded data, withhold recorded data from the processing device, take another action, or combinations thereof. On the other hand, if the accelerometer&#39;s measurements or the pressure sensor&#39;s measurements exhibit patterns that suggest that the user is pedaling, the processing device may incorporate the measurements into the calculations for determining a calorie count, stroke specific calculations, torque, other determinations, or combinations thereof. In such examples, the user may start and stop his or her workout by turning on or off the shoe&#39;s sensors to avoid integrating non-relevant data into the user&#39;s fitness information. 
     The pressure sensor and other components with the shoe can be powered with an energy harvesting mechanism that minimizes or eliminates batteries or an external power source. This reduces the weight of the shoe and spares the user from having to replace the batteries. Such energy harvesting mechanisms can include kinetic capture mechanisms, piezoelectric mechanisms, self-powered generator mechanisms, thermopile mechanisms, or combinations thereof. In some examples, the movement of the shoe causes coils to pass through a magnetic field. Such movement may be achieved through allowing some internal components of the shoe to move relative to other internal components as the shoe moves. For example, a magnet may move relative to coils as the shoe moves. In other examples, the coils may move in relation to a magnetic field. In either example, the differential movement between the coils and the magnetic field may generate an electrical current in the coils, which current may be directed to a battery or directly to the components of the shoe that user electrical power. 
     The monitoring system may include a shoe and a sole integrated into the sole. A connection mechanism may be attached to an underside of the sole and be shaped to connect the sole to a pedal. A pressure sensor may be incorporated into the shoe that senses a force exerted on the pedal when the shoe is connected to the pedal through the connection mechanism. In some cases, the pressure sensor can distinguish between upward forces imposed on the pedal and downward forces imposed on the pedal. 
     The measurements of the pressure sensor and the accelerometer (in those embodiments that include an accelerometer) may be transmitted to an external device, such as a mobile device carried by the user while on the exercise machine, another computing device, a network device, another type of device, or combinations thereof. Such a computing device may quantify the forces exerted onto the pedal and use such force determinations to determine a calorie count or another unit of energy consumption performed by the user. 
     The connection mechanism that connects the shoe to the pedal may be a clipless pedal system where a cleat receptacle of the underside of the shoe interlocks with the cleat from the pedal. The pressure sensor may be disposed proximate the cleat receptacle. 
     In some cases, the pressure sensor is a capacitive based pressure sensor. In such an example, the capacitive based pressure sensor may comprise electrically conducting plates that are spaced a distance from each other. The electrically conducting plates may move such that the distance between the plates narrows during a downward force on the pedal and the distance widens during an upward force on the pedal. 
     Any appropriate type of shoe may be used in accordance with the principles described herein. In some examples, the shoe is a cycling shoe that has a sole made of a stiff material to minimize flexing of the sole as a force is transferred from the shoe to the pedal. The clipless pedal system includes a cleat receptacle in the sole of the shoe. The cleat protrudes upward from the pedal and is shaped to interlock with cleat receptacle of the shoe. In some examples, the cleat snaps into a spring loaded mechanism incorporated into the sole of the shoe. The cleat may be made of any appropriate material, such as metal, plastic, or other types of material. Further, the cleat may have any appropriate type of shape to interlock with the shoe&#39;s sole. 
     Any appropriate type of pedal may be used with the shoe as long as the pedal is capable of interlocking with the shoe through the connection mechanism. In some examples, the pedal can interlock with the shoe on both faces of the pedal, while in other examples, the pedal can interlock with just a single face of the shoe.