Method for Controlling a Prosthetic Foot

Abstract

The invention relates to a method for controlling a prosthetic foot that has a foot part and a lower leg part which are connected to each other by means of a joint that allows a plantar flexion and a dorsal flexion, the damping behavior of the joint being adjustable,

wherein the method comprises the following steps: a) detecting measured values which allow for statements to be made about the rollover behavior of the prosthetic foot by means of at least one sensor, b) comparing the detected measured values and/or at least one parameter determined from said values with stored target values, and c) adjusting the damping behavior depending on the comparison.

Claims

1-12. (canceled)

13. A control method performed by a controller for a prosthetic foot to adjust a damping behavior of a joint connecting a foot part and a lower-leg part of the prosthetic foot, wherein the method comprises: a) detecting, using at least one sensor, sensor data describing a rollover behavior of the prosthetic foot, b) comparing at least one of the sensor data or at least one parameter determined from the sensor data with stored target data, and c) generating a control signal based on the comparing, the control signal configured to adjust the damping behavior of the joint.

14. The method of claim 13, wherein the control signal instructs the joint to adjust the damping behavior to account for at least one of a change in a shoe used on the prosthetic foot or a change in a state of movement of the prosthetic foot.

15. The method according to claim 13, wherein the damping behavior is only adjusted when the sensor data or the at least one parameter determined from the sensor data exceed the target values by a predetermined gap.

16. The method according to claim 13, wherein the sensor data is detected multiple times during a step cycle, wherein a trend of the sensor data across at least one part of a step cycle of the prosthetic foot, is compared with a trend of the stored target data.

17. The method according to claim 16, wherein the trend of the sensor data is compared with the trend of the stored target data across an entire step cycle.

18. The method according to claim 13, wherein the damping behavior is a plantar damping behavior during a plantar flexion of the joint, and a path of the plantar damping is adjusted via at least one of an angle of an ankle of the prosthetic foot or an angle of the lower leg part , wherein the path is adjusted at a start of a heel strike during a step of the prosthetic foot or before the start of the heel strike, and no further adjustment of the path occurs over a remaining course of the step.

19. The method according to claim 13, wherein the sensor data includes a vertical force and a torque on the joint, wherein at least one of a force application point or a chronological profile of the force application point, is determined from the sensor data.

20. The method according to claim 19, wherein the sensor data contains at least one of the force application point or the chronological profile of the force application point, and the at least one sensor comprises a plurality of pressure sensors.

21. The method of claim 20, wherein the plurality of pressure sensors comprise a pressure-sensitive layer on a lower side of a sole of the foot part.

22. The method according to claim 19, wherein the chronological profile of the force application point is approximated by a segment of a circle with a center point and radius, which are compared with at least one of a stored center point or radius.

23. The method according to claim 13, wherein the sensor data comprises one or more of: a lower leg angle and a foot angle, or chronological profiles of the lower leg angle and the foot angle.

24. The method according to claim 21, further comprising determining at least one of a ratio of the lower leg angle to the foot angle or a chronological profile of the ratio.

25. The method according to claim 13, wherein at least one of the comparison or the adjustment of the damping behavior is performed multiple times during at least a part of a step cycle.

26. The method of claim 23, wherein the multiple times occur at equidistant intervals during the at least a part of the step cycle.

27. The method of claim 23, wherein the at least a part of the step cycle comprises an entire step cycle.

28. The method according to claim 13, wherein the damping is at least one of a hydraulic or magnetorheological damping.

29. The method of claim 13, wherein the foot part comprises at least one spring element having a spring stiffness, and further comprising adjusting the spring stiffness when the sensor data exceeds a predetermined distance from the target data.

30. A prosthetic foot comprising a foot part and a lower leg part that are connected to each other via a joint which allows a plantar flexion and a dorsal flexion, a damping behavior of the joint being adjustable, and an electronic data processing device configured to perform a method according to claim 1.

31. A non-transitory computer-readable storage medium storing instructions configured to cause a hardware controller to adjust a damping behaviour of a joint connecting a foot part and a lower leg part of a prosthetic foot, wherein the instructions comprise instructions for: a) detecting, using at least one sensor, sensor data describing a rollover behavior of the prosthetic foot, b) comparing at least one of the sensor data or at least one parameter determined from the sensor data with stored target data, and generating a control signal based on the comparing, the control signal configured to adjust the damping behavior of the joint.

Description

[0032] In the following, some examples of embodiments of the present invention will be explained in more detail by way of the attached figures: They show

[0033] FIGS. 1 to 3—schematic depictions of process sequences according to various examples of an embodiment of the present invention and

[0034] FIG. 4—the course of an example measured value.

[0035] FIG. 1 depicts a simple process sequence. First, initial damping values for the damping of the joint of the prosthetic foot are determined in a determination step 2. With these initial damping values, at least the first step taken with the prosthetic foot is carried out.

[0036] In a detection step 4, the measured values are detected by means of the at least one sensor that is arranged on the prosthetic foot or an element attached to it. These measured values relate, for example, to the course of a force application point as a function of the lower leg angle and/or the ankle angle. To be able to determine the course, the position of the force application point must be recorded several times in succession at least across one section of the step. Measurement preferably commences upon the heel strike and the measurements preferably extend across the entire plantar flexion phase of the step.

[0037] In a comparison step 6, the course of the force application point measured in this manner is compared with a target course. A gap between the measured course and the target course is determined and the deviation quantified.

[0038] On the basis of this gap, the damping behavior is adjusted in an adjustment step 8, preferably before the start of the next step. The detection step 4 is then conducted during the next step and the respective measured values, i.e. the course of the force application point in the present case, are detected once again.

[0039] FIG. 2 shows a similar process. In this case, initial damping values for the joint of the prosthetic foot are also determined in the determination step 2. The measured values are subsequently detected in the detection step 4. They are compared with corresponding target data in the comparison step 6. Unlike the example of an embodiment shown in FIG. 1, an additional test step 10 is used check whether the deviation identified in the comparison step 6, i.e. the gap between the measured values and/or the at least one parameter determined from said values and the stored target values, exceeds a predetermined limit. If this is not the case, no adjustment is made to the damping behavior along the “no” course 12. The deviation is too small. Instead, a detection step 4 is performed again during the next step taken by the wearer with the prosthetic foot.

[0040] However, if the determined gap is greater than the predetermined limit, a transition is made along the “yes” course 14 to the adjustment step 8, so that the damping behavior of the joint is adjusted.

[0041] FIG. 3 depicts a detailed representation of the method. The determination step 2 has been omitted for reasons of clarity. The detection step 4 comprises the detection of measured values, which are sensor data, for example. FIG. 3 shows two detection steps 4, but it is not absolutely essential to perform both. They describe different methods that can be carried out as an alternative or in addition to one another. The measured values detected during the lower detection step 4 are recorded in a recording step 16 across at least one part of the stance phase of the step, but preferably across the entire stance phase of the step.

[0042] The measured values resulting from the upper detection step 4 are converted into at least one parameter in a conversion step 18, said parameter being based on the measured values. In the next step in the method, the parameter calculated in this way is recorded across at least one part of the stance phase of the step, but preferably across the entire stance phase of the step. This is therefore also a recording step 16.

[0043] Following this recording step 16, the calculated and recorded parameter can be directly compared in the comparison step 6 with target values, which are provided as reference values from an electronic data memory 20, which is only depicted schematically. The adjustment of the damping behavior required on the basis of this comparison is subsequently carried out during the adjustment step 8. Alternatively, in a second conversion step 22, a further parameter can be generated from the course of the characteristic value or the previously calculated parameter. If this is the case, this course of the characteristic value or parameter is then compared in the comparison step 6 and, on the basis of this comparison, the damping behavior adjusted during the adjustment step 8.

[0044] In a preferred embodiment of the method, the measured values detected in the lower detection step 4, which have been recorded in the lower recording step 16, are processed along with the parameters determined in the second conversion step 22, for example by creating a phase diagram 24. This can then also be compared with target values from the electronic data memory 20 in the comparison step 6.

[0045] FIG. 4 schematically depicts a course of a measured value. The position of the force application point is plotted on the vertical Y-axis and the foot angle, i.e. the angle between the foot part and the ground on which the wearer of the prosthesis walks, is plotted on the horizontal X-axis. A target curve 26 shows the desired course. During a step, the course begins in the lower left quadrant. The force application point (COP) is in the heel area and begins upon heel strike. This is shown by the first pictogram 28. If one follows the target curve for the increasing foot angle, one sees that the force application point initially remains at the heel before moving upwards in the diagram shown, i.e. towards the forefoot.

[0046] The origin of the diagram is the point at which the foot rests completely on the ground and the lower leg swings over the foot. This is schematically depicted by the second pictogram 30. As the foot angle increases, the force application point continues to move towards the forefoot before remaining in the toe area until the toes leave the ground. This situation is depicted in the third pictogram 32.

[0047] Various measured curves are represented by the thin solid line 34 and the dashed line 36. In the case of the line 34, the force application point moves away from the heel of the foot earlier than in the target curve, and the plantar flexion of the foot is insufficient. A heel lever, represented by the double arrow 38, is thereby reduced. To rectify this deviation from the target curve, damping is reduced, i.e. the resistance opposing a movement is decreased. This allows the line 34 to be moved towards the target curve. The plantar flexion of the foot in now quicker.

[0048] The dashed line 36 deviates from the target curve in the other direction. Here, the damping is too soft, meaning that the plantar flexion of the foot is too quick and the force application point therefore does not initially move as the foot angle increases; it only moves from the heel towards the forefoot when the foot angle is greater than desired. In this case, damping should be increased.

REFERENCE LIST

[0049] 2 determination step [0050] 4 detection step [0051] 6 comparison step [0052] 8 adjustment step [0053] 10 test step [0054] 12 “no” course [0055] 14 “yes” course [0056] 16 recording step [0057] 18 conversion step [0058] 20 electronic data memory [0059] 22 second conversion step [0060] 24 phase diagram [0061] 26 target curve [0062] 28 first pictogram [0063] 30 second pictogram [0064] 32 third pictogram [0065] 34 solid line [0066] 36 dashed line [0067] 38 heel lever