JP2011239887A - Threshold adjustment method for idling leg or standing leg determination algorithm used for walking assistant device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a threshold adjustment method for a walking assistant device having thresholds set for each variable, which is 2 or more out of state variable groups indicating physical states of a walking user, and having a determination algorithm installed for determining timings for switching an idling leg or a standing leg in combination with a size correlation between values of each measured state variable and the thresholds.SOLUTION: The adjustment method includes: a recording step of recording aging changes of state variables which are 2 or more when a user uses the walking assistant device; a setting step of setting the thresholds; and a displaying step of displaying the graph indicating the aging changes of the recorded state variables, which are 2 or more, displaying timings where the graphs cross the thresholds set for each graph, and displaying a determination result to which the determination algorithm is applied using the set thresholds. The method repeats the setting step and display step by changing the set thresholds.

Description

  The present invention relates to a technique for adjusting parameters of a walking support device. In particular, the present invention relates to a technique for adjusting a parameter (threshold value) for determining the switching timing between a free leg state and a standing leg state.

  Research has been conducted on a walking support device that is attached to a user's leg and supports a walking motion by applying torque to the user's leg joint (for example, Patent Document 1 and Patent Document 2). In such a walking support device, a control rule for support may be changed depending on whether a leg to be supported is in a free leg state or a standing leg state. This is because while the load for supporting the weight is applied to the standing leg, the load applied to the free leg is small, but the swinging movement is greatly different.

JP 2004-329520 A JP 2003-79684 A

  As described above, the walking support device is required to have a function of determining whether the user's leg is in the free leg state or the standing leg state. In particular, it is important to accurately determine the switching timing between the free leg and the standing leg. Up to now, for example, a determination algorithm for determining the switching timing of the free leg / stand leg based on the output of the ground sensor on the sole, or the switching timing of the free leg / stand leg based on the output of the sensor that measures the speed of the foot is used. A judgment algorithm has been devised. The speed of the foot can be obtained from the angular speed (or time-series data of the angles) of each joint of the leg. Therefore, the “sensor for measuring the speed of the foot” can be replaced with a sensor for measuring (or estimating) the angular speed of each joint of the leg. Hereinafter, for the sake of simplicity, the “sensor for measuring the position and / or speed of the foot” may be abbreviated as a “foot position sensor”.

  A determination algorithm that relies solely on the output of the ground sensor or the output of the foot position sensor may not be able to accurately determine the switching timing between the free leg and the standing leg. For example, the output of the grounding sensor changes when the sole of the foot rubs the walking surface unintentionally, but when it rubs the walking surface, it is determined as “landing timing (ie, switching timing from free leg to standing leg)” Should not. Therefore, a threshold value is set for each of two or more state variables in the state variable group representing the physical state of the user at the time of walking. We examined a judgment algorithm to determine the switching timing between the free leg and the standing leg. The two or more state variables described above preferably include two of the foot position, foot load (floor reaction force), and foot horizontal direction speed.

  For example, a pressure sensor that measures the foot load (the floor reaction force that the grounded foot receives from the walking surface) is used as a grounding sensor, and whether the measured value of the pressure sensor exceeds a predetermined threshold or not, When adopting a one-variable judgment algorithm that judges the timing of switching to a state (that is, adopting an algorithm that judges the switching timing of a free leg and a stance based on the magnitude relationship between the value of one state variable and a threshold) It is not difficult to obtain the threshold value by trial and error. However, in the case of adopting an algorithm that determines the switching timing of the free leg / stand by the combination of the magnitude relation between the value of two or more state variables and the threshold, it is difficult to adjust the threshold because the number of the magnitude relation combinations increases. . As the number of state variables increases, it becomes more difficult to adjust the threshold. The present invention has been created in view of the above problems. One technical teaching disclosed herein provides a technique for adjusting the threshold of such a decision algorithm.

  One technical teaching disclosed in the present specification provides a threshold adjustment method for a determination algorithm of a swing leg / stance switch timing in a walking support device. As described above, in the determination algorithm, a threshold is set for each of two or more state variables in the state variable group representing the physical state of the user at the time of walking when the user uses the walking support device. The timing for switching between the free leg and the stance is determined based on the combination of the measured value of each state variable and the magnitude relationship between the threshold values. This threshold value adjusting method includes a recording step, a setting step, and a display step. The recording step records changes with time of the two or more state variables when the user uses the walking support device. In the setting step, the threshold value is set. The setting here may be a temporary setting. Also, a temporary threshold may be set when recording the change of the state variable over time. The display step displays a graph showing a change over time of two or more recorded state variables and a timing at which the graph (change over time of each state variable) crosses a set threshold for each graph. The determination result to which the above determination algorithm is applied using the set threshold is simultaneously displayed. This adjustment method is characterized by repeating the setting step and the display step while changing the threshold value to be set.

  In particular, this method graphically displays the timing at which each state variable crosses the threshold value, so that it is easy to grasp which state variable has a great influence on the determination of the swing leg / standpoint switching timing. It is also possible to grasp at a glance which state variable crosses the threshold first. An operator who adjusts the threshold value can efficiently determine an appropriate threshold value while viewing the display. In addition, the actual walking support device only needs to be moved once, and after changing the threshold value, the determination algorithm is tried using the temporal change of the recorded state variable. There is no need to change the threshold and move the walking support device on a trial basis. Note that the swing / stud switching timing may mean one of the switching timing from the swinging leg state to the standing leg state and the switching timing from the standing leg state to the swinging leg state, or may include both. There is also.

  Another technical teaching disclosed in the present specification provides an adjustment work support device that supports the above-described adjustment of the threshold value. The apparatus includes a storage device that stores changes over time of two or more state variables during walking when the user uses the walking support device, an input device that receives a threshold setting, and a display device. The display device displays a graph showing a change over time of two or more stored state variables and a timing at which the graph (change over time of each state variable) crosses a set threshold for each graph, A determination result obtained by applying the above-described determination algorithm using the set threshold is displayed. As described above, the “two or more state variables” preferably include two of the foot position, the foot load (the reaction force that the foot receives from the walking surface), and the foot horizontal direction speed.

  ADVANTAGE OF THE INVENTION According to this invention, adjustment of the said threshold value of the free leg / stand switch switching timing determination algorithm mounted in a walking assistance apparatus can be performed efficiently.

The schematic diagram of a walking assistance apparatus is shown. The schematic diagram of an adjustment work assistance apparatus is shown. An example of a display screen is shown.

  With reference to the drawings, a method for adjusting the threshold value of the swing / standpoint switching timing determination algorithm of the walking support device and an adjustment work support device used in the method will be described. FIG. 1 is a schematic diagram of an example walking support apparatus. FIG. 2 is a schematic diagram of the adjustment work support device connected to the walking support device. FIG. 3 shows an example of a display screen by the adjustment work support apparatus. First, the walking support device 10 will be described.

  As shown in FIG. 1, the walking support device 10 is attached to the leg of the user 100. In this embodiment, the walking support device 10 is attached to the left leg of the user 100. As will be described later, the walking support device 10 includes a motor 42 that applies torque to the left knee joint of the user. The walking support device 10 is used for rehabilitation of the user 100 who cannot freely move the knee joint of one leg (left leg), for example. By using the walking support device 10, it is possible to promote the functional recovery of the user 100 and reduce the labor of an assistant who assists the user 100.

  A coordinate system used in the description of the walking support device 10 will be described. The X axis is determined in the front-rear direction of the user 100 wearing the walking support device 10, the Y axis is determined in the left-right direction of the user 100, and the Z axis is determined in the up-down direction of the user 100. The positive direction of the X axis is the front of the user 100, the positive direction of the Y axis is the left side of the user 100, and the positive direction of the Z axis is the upper side of the user 100. In the field of robot engineering, the X axis, Y axis, and Z axis in a coordinate system fixed to a robot (human body in this embodiment) are called a roll axis, a pitch axis, and a yaw axis, respectively. .

  The mechanical structure of the walking support device 10 will be described. As shown in FIG. 1, the walking support device 10 includes a controller 12, a thigh link 20, a crus link 50, and a foot link 90. The controller 12 has a built-in battery together with a CPU for controlling a motor 42 (described later). The controller 12 supplies power to each part (sensor and motor) of the walking support device 10 and controls the motor 42. The controller 12 is attached to the trunk (waist) of the user 100, for example. The controller 12 is provided with a mounting belt 14 for fixing to the trunk of the user 100. The position where the controller 12 is mounted is not particularly limited, and may be mounted on the back of the user 100, for example.

  The thigh link 20, the lower leg link 50, and the foot link 90 are attached to the affected leg 110 (here, the left leg) of the user 100 that needs assistance. Specifically, the thigh link 20 is attached to the thigh 112, the crus link 50 is attached to the crus 116, and the foot link 90 is attached to the foot 118. Note that in this specification, when simply expressed as the affected leg 110, it includes not only the thigh 112, the knee 114, and the lower leg 116 but also the foot 118 (portion beyond the ankle).

  The thigh link 20 includes a thigh support plate 22, a thigh belt 24, and a frame 26. The thigh support plate 22 is fixed to the frame 26. Further, the thigh support plate 22 abuts on the front surface of the thigh 112 of the user 100 and is fixed to the thigh 112 of the user by the thigh belt 24. That is, the thigh link 20 is fixed to the user's thigh 112.

  The lower leg link 50 includes a lower leg support plate 52 and a frame 56. The lower leg support plate 52 is fixed to the frame 56. The lower leg support plate 52 abuts on the front surface (under the knee) of the lower leg 116 of the user 100. That is, the lower leg link 50 is attached to the user's lower leg 114.

  The foot link 90 includes a foot support plate 92, shoes 94, and a frame 96. The foot support plate 92 is fixed to the frame 96. A shoe 94 is fixed on the foot support plate 92. That is, the foot link 90 is attached to the user's foot 118.

  The thigh link 20 and the crus link 50 are connected via the rotary joint 40. The rotary joint 40 is a rotary joint around one axis of the pitch axis (Y axis), and rotatably connects the frame 26 of the thigh link 20 and the frame 56 of the crus link 50. That is, the rotary joint 40 rotatably connects the crus link 50 to the thigh link 20.

  The rotary joint 40 located outside the affected leg 110 includes a motor 42, an angle sensor (encoder) 43, and a speed reducer. The rotary joint 40 corresponds to a drive unit that rotates the crus link 50 relative to the thigh link 20. The rotary joint 40 is connected to the controller 12 via the electric cable 16, is driven by electric power supplied from the controller 12, and its operation is controlled by the controller 12.

  The lower leg link 50 and the foot link 90 are connected via an ankle rotation joint 70. The ankle rotation joint 70 is a rotation mechanism around one pitch axis, and the frame 96 of the foot link 90 is connected to the frame 56 of the crus link 50 so as to be relatively rotatable.

  The controller 12 of the walking support device 10 stores a target trajectory describing a change over time of the target value of the left knee joint angle during walking, and a motor is used so that the angle of the user's left knee joint follows the target trajectory. 42 is controlled. For the walking support device 10, in order to match the timing on the target trajectory with the actual movement of the knee joint angle, the timing at which the user's left leg switches from the free leg to the standing leg (ie, the landing timing) and the standing leg to the free leg are switched. It is important to determine the timing to change (that is, the bed leaving timing). Hereinafter, the timing for switching from the free leg to the standing leg and the timing for switching from the standing leg to the free leg are simply referred to as “switching timing”.

  In order to determine the switching timing, the walking support device 10 includes several sensors. The sensor will be described. The main sensors included in the walking support device 10 are an inclination angle sensor 32, an angle sensor 43, and a pressure sensor 98. The inclination angle sensor 32 is attached to the thigh link 20 and measures an inclination angle around the pitch axis of the thigh 112 with respect to the vertical direction. The angle sensor 43 measures the rotation angle of the crus link 50 (that is, the rotation angle of the rotary joint 40). The rotation angle of the lower leg link 50 corresponds to the knee joint angle of the user 100. The angle sensor 43 is also used for feedback control that causes the rotation angle of the rotary joint 40 to follow the target rotation angle. The pressure sensor 98 is provided in the foot link 90 and measures the floor reaction force that the foot 118 of the affected leg 110 wearing the walking support device 10 receives from the walking surface. Hereinafter, the floor reaction force may be expressed as “foot load”.

  The sensor measures a state variable group that represents the physical state of the user during walking. In the walking support device 10 of the present embodiment, the state variables are specifically the position of the foot of the leg wearing the walking support device 10 and the floor reaction that the foot of the leg wearing the walking support device 10 receives from the walking surface. The force (foot load) and the foot horizontal direction speed of the leg on which the walking support device 10 is mounted. The position of the foot and the speed in the foot horizontal direction are obtained from the sensor data of the tilt angle sensor 32 and the angle sensor 43. Note that the position of the foot is the position of the foot with respect to the position of the trunk and is not a position in the absolute coordinate system. The foot load is obtained from the sensor data of the pressure sensor 98. The relationship between these state variables and the switching timing will be described next.

  In the free leg state, the foot load (floor reaction force) is zero, and when landing, the foot load is generated. Therefore, the foot load increases rapidly from zero at the timing of switching from the free leg to the standing leg. Also, the foot load suddenly decreases to zero at the timing of switching from the standing leg to the free leg. Note that noise is generated in the pressure sensor 98 during the free leg period due to the inertial force when the leg swings. Therefore, a load threshold value close to zero can be set, and if the measured foot load falls below the load threshold value, it can be estimated that it is in a free leg state, and if it exceeds the load threshold value, it is estimated that it is in a standing state. it can. In other words, the timing at which the measured foot load crosses the load threshold is switched and can be an index for determining the timing. However, when the foot rubs the walking surface unintentionally, it is assumed that the foot load temporarily exceeds the load threshold, and therefore it is not accurate to determine the switching timing based only on the foot load. The load threshold for determining the switching timing from the free leg to the standing leg may be different from the load threshold for determining the switching timing from the standing leg to the free leg.

  In walking motion, the free leg lands in front of the trunk. That is, the leg position of the free leg is forward of the trunk at the timing of switching from the free leg to the standing leg. In addition, the stance stand leaves behind the trunk. That is, it may be a necessary condition for the switching timing from the free leg to the standing leg that the measured foot position is positioned forward of the trunk by a distance threshold. Moreover, it may be a necessary condition for the switching timing from the standing leg to the free leg that the measured foot position is located behind the trunk by a distance threshold. However, it should be noted that the relationship between the foot position and the distance threshold is a necessary condition and not a sufficient condition.

  In a walking motion, the leg of the swing leg is usually moving (that is, has a speed), and the leg of the stance leg is stationary. Therefore, when the foot horizontal direction speed is larger than the speed threshold, it can be estimated that the leg is in the swinging state, and when the foot horizontal direction speed is smaller than the speed threshold, it is estimated that the leg is in the standing state. Here, the speed threshold is set to a value close to zero. However, since the instantaneous speed becomes zero when the swinging direction of the free leg is switched from the front to the rear, it is not accurate to determine the switching timing based only on the foot horizontal direction speed.

  As described above, the foot position, the foot load, and the foot horizontal direction speed can all be indexes for determining the switching timing. However, since any state variable alone may cause an erroneous determination, it is preferable to determine the switching timing based on the combination of the magnitude relationship between the state variable and the threshold value. The walking support device 10 implements a determination algorithm that determines the switching timing based on the combination of the magnitude relations between the three state variables and the respective threshold values. For example, when the walking support device 10 satisfies the conditions of foot position> first foot position threshold, foot load> first load threshold, and foot horizontal direction speed <first speed threshold. Is determined as the switching timing from the free leg to the standing leg. In addition, when the condition that the foot position <the second foot position threshold is satisfied, the foot load <the second load threshold is satisfied, and the foot horizontal direction speed> the second speed threshold is satisfied, the walking support device 10 is satisfied. Is determined as the switching timing from the standing leg to the free leg. That is, the above-described determination algorithm is implemented in the walking support device 10.

  Here, when using three state variables of the foot position, the foot load, and the foot horizontal direction speed, it takes a lot of labor to set an appropriate threshold value for each state variable. Therefore, a method for efficiently adjusting the threshold value and a device for supporting the method are required. Next, a threshold adjustment method and an apparatus that supports the method will be described.

  FIG. 2 shows a system diagram of an adjustment work support apparatus 200 that supports a threshold adjustment work by an operator. The adjustment work support device 200 is a personal computer that includes a main body 202, a keyboard (input device) 204, and a display device 206. The main body 202 is connected to the walking support apparatus 10 by USB, for example.

  First, the worker who adjusts the threshold causes the user to wear the walking support device 10 in which the temporary threshold is set and walk. At this time, the change with time of the state variable is sent to the main body 202 and recorded. That is, the main body 202 corresponds to a storage device that stores (records) a change with time of the state variable when the user uses the walking support device 10. Further, the process of storing the change with time of the state variable in the main body 202 corresponds to a recording step of recording the change with time of the state variable when the user uses the walking support device.

  Next, the operator operates the keyboard 204 to input a preferable threshold value. In other words, the keyboard 204 receives a threshold setting. The process of inputting a threshold corresponds to the setting step. The main body 202 of the adjustment work support device 200 has the same algorithm as the determination algorithm installed in the walking support device 10. Can be executed. The main body 202 displays a graph showing the change over time of the recorded state variable and the timing at which the curve of the graph (that is, the change over time of the state variable) crosses the set threshold value for each graph and is inputted. The determination result obtained by executing the above-described determination algorithm using the determined threshold is displayed on the display device 206. At this time, the processing performed by the main body 202 and the display device 206 is a graph showing the change over time of the recorded state variables, and the timing at which the graph crosses the threshold value input (set) via the keyboard 204 for each graph. This corresponds to a display step of displaying the determination result obtained by executing the above-described determination algorithm using the input (set) threshold value.

  The operator inputs another threshold value again while looking at the displayed determination result. The adjustment work support apparatus 200 re-executes the determination algorithm using the re-input threshold and the recorded temporal change of the state variable, and displays the result again. The operator repeatedly inputs the threshold value and confirms the displayed result to determine an appropriate threshold value.

  FIG. 3 shows an example of the display screen. The display screen 207 shows several windows. The window 215 displays the input threshold value. Boxes 215a, 215b, and 215c are small windows that display the values of the load threshold value, the foot position threshold value, and the foot speed threshold value input via the keyboard 204, respectively.

  The window 210 shows the determination result of the determination algorithm implemented in the walking support device 10 when the walking support device 10 is operated and the state variables are recorded. The period in which the graph passes the upper side of the time axis represents the stance period, and the period in which the graph passes the lower side of the time axis represents the free leg period.

  Windows 212, 213, and 214 are windows that display graphs showing changes in recorded state variables over time. In the window 212, a graph showing a change with time of the recorded foot load is displayed. In the window 213, a graph showing a change with time of the recorded foot position is displayed. The window 214 displays a graph showing the temporal change in the recorded foot horizontal speed. The windows 212, 213, and 214 also display the threshold values input for the respective state variables. T1 displayed in the window 212 indicates a foot load threshold value. T2 displayed in the window 213 indicates a foot position threshold value. T3 displayed in the window 214 indicates a foot speed threshold value.

  The main body 202 executes the determination algorithm by using the recorded change of the state variable with time and the input threshold value, and also shows the determination result. A window 211 is a window showing the determination result. Further, the display screen 207 displays the timing at which each state variable crosses the input threshold value (set threshold value) for each graph of the state variable. Note that arrows 212a, 212b, 213a, 213b, 214a, 214b in the drawings described below are displayed across a plurality of windows. For example, the arrows 212a and 212b are displayed on the screen across the window 212 and the window 211.

  Arrows 212a and 212b indicate the timing at which the recorded foot load graph (change over time) crosses the foot load threshold T1. Arrows 213a and 213b indicate the timing at which the recorded foot position graph crosses the foot position threshold T2. Arrows 214a and 214b indicate the timing at which the graph of the recorded foot horizontal speed crosses the foot speed threshold T3. All the arrows extend to the window 211 indicating the determination result, so that the relationship between the crossing timing and the switching timing can be grasped at a glance. For example, the timing indicated by reference numeral 211a indicates the switching timing from the free leg to the standing leg determined by the determination algorithm. Prior to this timing, the recorded foot position is above the foot position threshold T2 (arrow 213a), and the recorded foot horizontal speed is below the foot speed threshold T3 (arrow 214a). At time 211a, the recorded foot load exceeds the foot load threshold T1. That is, at timing 211a, the conditions of foot position> foot position threshold value T2, foot load> foot load threshold value T1, and foot horizontal direction speed <foot speed threshold value T3 are satisfied. The timing 211a is determined as the switching timing from the free leg to the standing leg. Similarly, at timing 211b, the conditions that foot position <foot position threshold T2 and foot load <foot load threshold T1 and foot horizontal direction speed> foot speed threshold T3 are satisfied, and the determination algorithm Determines that the timing 211b is the switching timing from the standing leg to the free leg.

  The operator verifies whether the determination result is appropriate while looking at the display screen 207. The most typical verification item is to verify whether or not the period that should be the stance period (or the swing leg period) is correctly determined from the state variable graph. If it is not correctly determined, it is obvious from the above display screen which state variable and threshold value are the cause. Further, for example, the worker verifies whether or not the free leg period and the stance period are divided according to the distribution assumed in the ideal walking motion. If the distribution is not classified according to the assumed distribution, it can be easily determined from the display screen 207 which threshold value is causing the expected determination result. While viewing the display screen 207, the operator changes the threshold value to be set, repeats the setting step and the display step, and determines an appropriate threshold value. In this way, by using the adjustment work support device 200 described above, it is possible to efficiently adjust the threshold value of the free leg / standpoint switching timing determination algorithm implemented in the walking support device.

  The adjustment method described above only needs to move the walking support device once. It is not necessary to repeatedly try the walking support device by changing the threshold value, and the threshold setting operation can be performed efficiently. Further, the previous determination result (window 210) and the determination result based on the newly input threshold value (window 211) are simultaneously displayed on the display device. This simultaneous display is also useful for threshold adjustment.

  The determination algorithm of the above embodiment employs three state variables, that is, foot position, foot load, and foot horizontal direction speed. The state variables to be adopted are not limited to these three. For example, it is also preferable to employ a swing angular velocity around the pitch axis of the thigh as a state variable for determining the timing of switching between the free leg and the stance.

  Also, the walking support device that is the target of the threshold adjustment method disclosed in this specification is not limited to the embodiment (walking support device 10). For example, a walking support device that can apply torque to the ankle joint together with the knee joint can also be a target of the threshold adjustment method disclosed in this specification.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

10: walking support device 12: controller 20: thigh link 32: tilt angle sensor 40: rotation joint 42: motor 43: angle sensor 50: leg link 90: foot link 98: pressure sensor 200: adjustment work support device 202: main body 204 : Keyboard (input device)
206: Display device 207: Display screen 210, 211, 212, 213, 214, 215: Window T1: Foot load threshold T2: Foot position threshold T3: Foot speed threshold

Claims (4)

A threshold is set for each of two or more state variables in the state variable group representing the physical state of the user during walking, and a combination of magnitude relations between the values of the measured state variables and the thresholds. A method for adjusting the threshold value of a walking support device that implements a determination algorithm for determining the timing of switching between a free leg and a stance.
A recording step for recording a change with time of the two or more state variables when the user uses the walking support device;
A setting step for setting the threshold;
The graph showing the change over time of the two or more state variables recorded and the timing at which the graph crosses the set threshold for each graph is displayed, and the determination algorithm is applied using the set threshold A display step for displaying the determination result,
A threshold adjustment method characterized by repeating the setting step and the display step while changing a threshold to be set.   The threshold value adjusting method according to claim 1, wherein the two or more state variables include two of a foot position, a foot load, and a foot horizontal speed. A threshold is set for each of two or more state variables in the state variable group representing the physical state of the user during walking, and a combination of magnitude relations between the values of the measured state variables and the thresholds. An adjustment work support device that supports the adjustment work of the threshold value of the walking support device that implements a determination algorithm for determining the timing of switching between the free leg and the stance.
A storage device for storing changes over time of the two or more state variables when the user uses the walking support device;
An input device that accepts the setting of the threshold;
The graph showing the change over time of the two or more state variables recorded and the timing at which the graph crosses the set threshold for each graph is displayed, and the determination algorithm is applied using the set threshold A display device for displaying the determination result;
An adjustment work support device comprising:   The adjustment work support apparatus according to claim 3, wherein the two or more state variables include two of a foot position, a foot load, and a foot horizontal direction speed.

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