METHOD FOR CONTROLLING AN ORTHOTIC OR PROSTHETIC DEVICE AND ORTHOTIC OR PROSTHETIC DEVICE

Abstract

The invention relates to a method for controlling an orthotic or prosthetic device and an orthotic or prosthetic device, which can be placed on the body of a user and secured, including a joint device having a proximal component and a distal component, which are pivotally mounted on one another about a pivot axis; at least one adjustable actuator which is arranged between the proximal component and the distal component and via which a movement behaviour relating to a pivoting of the proximal component relative to the distal component can be adjusted; at least one detection device for detecting muscle contractions; and a control device which is coupled to the detection device and to the actuator, processes (electrical) signals from the detection unit, and adjusts the actuator according to the signals, wherein the detection device is designed for detecting muscle contractions.

Claims

1. A method for controlling an orthotic or prosthetic device which can be placed on the body of a user and secured thereon, comprising: a. a joint device with a proximal component and a distal component, which are mounted pivotably on each other about a pivot axis; b. at least one adjustable actuator, which is arranged between the proximal component and the distal component and via which a movement behavior with respect to a pivoting of the proximal component relative to the distal component is adjustable; c. at least one detection device for detecting muscle contractions; and d. a control device which is coupled to the detection device and to the actuator, wherein the control device processes (electrical) signals from the detection device, and adjusts the actuator according to the signals; wherein the detection device is designed for detecting muscle co-contractions and is arranged on a limb of the user and coupled to the control device, in that at least one muscle co-contraction is detected by the detection device, and in that the movement behavior is changed by the actuator according to the detected muscle co-contraction.

2. The method as claimed in claim 1, wherein the duration and/or intensity of the muscle co-contraction is detected, and the movement behavior is changed according to the duration and/or intensity of the muscle co-contraction.

3. The method as claimed in claim 1, wherein the actuator provides a movement resistance against pivoting, and the movement resistance is increased when a muscle co-contraction is detected.

4. The method as claimed in claim 1, wherein with an increasing co-contraction intensity and/or co-contraction duration, the movement resistance is increasingly heightened, and/or with a decreasing co-contraction intensity and/or co-contraction duration and/or at the end of a co-contraction and/or upon detection of another co-contraction, it is reduced by an active trigger and/or a voice command.

5. The method as claimed in claim 4, wherein the movement resistance is increased more quickly than it is reduced.

6. The method as claimed in claim 1, wherein the change in the movement behavior is superposed on a preset control program.

7. The method as claimed in claim 6, wherein the change influences the extent of the movement influence and/or the duration of the movement influence.

8. The method as claimed in claim 1, wherein the muscle contractions are transmitted from the detection device to the control device as myoelectric signals, pressure signals, inductively generated signals and/or opto-electronically generated signals.

9. The method as claimed in claim 1, wherein at least one sensor detects forces, angles, positions, accelerations and/or moments on the orthotic or prosthetic device and transmits sensor signals to the control device, and the movement behavior is changed on the basis of the sensor signals.

10. The method as claimed in claim 1, wherein the raw signals detected by the detection device are processed in a pre-processing unit and are transmitted in processed form to the control device.

11. The method as claimed in claim 1, wherein the detected muscle co-contractions are checked for plausibility and, in the absence of plausibility, changes in the movement behavior are rejected or reversed.

12. An orthotic or prosthetic device which can be placed on the body of a user and secured thereon, comprising a. a joint device with a proximal component and a distal component, which are mounted pivotably on each other about a pivot axis; b. at least one adjustable actuator, which is arranged between the proximal component and the distal component and via which a movement behavior with respect to a pivoting of the proximal component relative to the distal component is adjustable; c. at least one detection device for detecting muscle contractions; and d. a control device which is coupled to the detection device and to the actuator, wherein the control device processes signals from the detection unit, and adjusts the actuator according to the signals, and wherein the detection device is designed for detecting muscle co-contractions.

13. The orthotic or prosthetic device as claimed in claim 12, wherein the detection device is designed as a surface electrode arrangement, as an implant, as a pressure sensor device, as an optical sensor device and/or as an inductively operating sensor device.

14. The orthotic or prosthetic device as claimed in claim 12, wherein the detection device is integrated in the proximal and/or distal component.

15. The orthotic or prosthetic device as claimed in claim 12, wherein at least one sensor for detecting forces, angles, positions, accelerations and/or moments is arranged on the orthotic or prosthetic device and coupled to the control device.

16. The orthotic or prosthetic device as claimed in claim 12, wherein the detection device is coupled to a pre-processing unit.

17. The orthotic or prosthetic device as claimed in claim 16, wherein the detection device and the pre-processing unit are designed as a common module.

18. The orthotic or prosthetic device as claimed in claim 16, wherein the detection device and/or the pre-processing unit can be switched off and/or are designed to be plug-and-play capable.

19. The orthotic or prosthetic device as claimed in claim 12, wherein the actuator is designed as a resistance device or drive.

20. An orthotic or prosthetic device which can be placed and secured on the body of a user, the device comprising: a. a joint device with a proximal component and a distal component mounted pivotably to each other about a pivot axis; b. at least one adjustable actuator which is arranged between the proximal component and the distal component and via which a movement behavior with respect to a pivoting of the proximal component relative to the distal component is adjustable; c. at least one detection device in the form of a surface electrode arrangement, implant, pressure sensor device, optical sensor device and/or an inductively operating sensor device for detecting muscle contractions, the detection device being integrated into the proximal and/or distal component of the device; and d. a control device which is coupled to the detection device and to the actuator, wherein the control device processes signals from the detection unit and adjusts the actuator according to the signals, and wherein the detection device is designed for detecting muscle co-contractions.

Description

[0026] Illustrative embodiments of the invention are explained in more detail below with reference to the accompanying figures, in which:

[0027] FIG. 1 shows a schematic representation of a prosthetic device in the form of a prosthetic knee joint;

[0028] FIG. 2 shows a variant of the prosthetic device according to FIG. 1;

[0029] FIG. 3 shows a schematic representation of a variant with a pre-processing unit;

[0030] FIG. 4 shows a schematic representation of a change in resistance when walking on the level;

[0031] FIG. 5 shows a schematic representation of a change in resistance when walking downward;

[0032] FIG. 6 shows an illustration of situations of involuntary co-contractions; and

[0033] FIG. 7 shows a schematic representation of a resistance curve.

[0034] FIG. 1 shows a schematic representation of a prosthetic device 10 in the form of a prosthetic knee joint with a thigh socket 11, which is fastened to a patient. The thigh socket 11 can be fastened to a thigh stump by different mechanisms, for example by suction socket technology, clamping, an osseointegrated fixation, or in other ways. Arranged at the distal end of the thigh socket 11 is a joint device 20 in the form of a prosthetic knee joint, which has a proximal component 21 with connection means for fastening to the thigh socket 11. On the proximal component 21, a distal component 22 in the form of a lower-leg part is pivotably mounted about a pivot axis 25. In the illustrative embodiment shown, the pivot axis 25 is formed as a knee joint axis, while in other applications, for example in a prosthetic ankle joint or in prosthetic or orthotic devices on the upper extremity, other joint axes are accordingly provided. As an alternative to a prosthetic device 10, an orthotic device can also be provided which, instead of replacing a limb, supports a limb that still has a natural joint. In the case of a cross-knee orthosis, a thigh rail is fixed to a thigh and a lower-leg rail is fixed to a lower leg, for example by buckles, straps or shells. The thigh rail and the lower-leg rail are coupled to each other via an orthotic knee joint so as to be pivotable about an axis. In the case of an ankle orthosis, the proximal component is a lower-leg rail and the distal component is a foot part which, in the region of the natural ankle joint axis, is arranged pivotably thereon via a joint. An orthotic device is also understood to mean exoskeletons.

[0035] An actuator 30 is arranged between the proximal component and the distal component 22; in the illustrative embodiment shown, the actuator 30 is mainly arranged on the distal component 22 and integrated in a housing. The actuator 30 can be designed as a resistance device, for example as a hydraulic damper, pneumatic damper or magnetorheological damper. It is also possible that the actuator is designed as a motor drive, for example as an electromotive drive, hydraulic drive or pneumatic drive. Even in an embodiment of an actuator 30 as a drive, it can be switched as a resistance device, for example by operating an electric motor in generator mode. Arranged on the proximal component 21 is a jib, which is coupled by a piston rod or a push rod to the resistance device or the drive, i.e. the actual actuator 30, wherein the actuator 30 is connected at the other end of the piston rod or of the push rod to the distal component 22.

[0036] The proximal component 21 executes a pivoting movement with respect to the distal component 22; in the position shown, the joint device 20 is in a position of maximum extension. From this position, a flexion movement takes place in which the posterior or rear face of the proximal component 21 is pivoted in the direction of the posterior face of the distal component 22, such that the angle on the posterior face between the two components 21, 22 decreases in the event of flexion and increases in the event of extension. As the flexion angle increases, the knee angle decreases. In order to be able to execute a pivoting movement adapted to the particular walking situation, both in the flexion direction and in the extension direction during walking, the actuator 30 is designed to be adjustable in order to influence the movement behavior during flexion and/or extension. By increasing the flexion resistance, for example, the maximum flexion angle or the minimum knee angle can be set, and, in the case of an extension movement, an increase in resistance can be provided shortly before the position of maximum extension is reached, in order to avoid a hard stop in the extension position. It is likewise possible to configure the actuator 30 to support the movement, that is to say as a drive for initiating or supporting a flexion movement and/or extension movement.

[0037] In order to adjust the actuator 30 and to influence the provided resistance or the provided support, the actuator is coupled to a control device 50 which, in the illustrative embodiment shown in FIG. 1, is integrated in the distal end region of the prosthesis socket 11. Data processing devices, connections, contact faces, interfaces and/or an energy store are arranged in the control device in order to process incoming sensor data or data from a detection device 60. In the illustrative embodiment shown in FIG. 1, the detection device 60 is designed as a surface electrode arrangement which is fastened by a belt 12 to the thigh socket 11 and the thigh. The surface electrodes 60 detect myo-electrical signals during the contraction of the thigh muscles and conduct these signals via cable or also wirelessly to the control device 50. In addition, at least one sensor 40 is arranged on the distal prosthesis component 22 in order to detect further data concerning the existing loads, forces, moments, angular positions, accelerations and/or spatial orientations and transmit them to the control device. Although sensors 40 are not required for carrying out the method, they are advantageous as a supplement.

[0038] The detection device 60, having a plurality of surface electrodes arranged circumferentially around the stump, allows muscle contractions to be detected via myo-electric signals. As an alternative to an arrangement on a belt 12, the surface electrodes can also be integrated in the prosthesis socket 11. The detection device 60 and the surface electrodes thereon are arranged and designed such that different muscle groups can be detected with regard to their activity. This makes it possible to detect muscles that are responsible for or involved in opposite movements, for example the quadriceps for extension and the leg biceps for flexion, and to detect muscle co-contractions, i.e. simultaneous tightening of muscle groups. Muscle co-contractions do not occur only in muscles or muscle groups that have an antagonistic action. Co-contractions can also occur and be detected when mutually independent muscle groups are tensioned, for example the abdominal muscles together with the hip flexor or the leg flexor.

[0039] FIG. 2 shows a variant of the prosthetic device, in which, in addition to a sensor 40 for detecting status information such as forces, moments, angular positions in space or accelerations, a further sensor device 40 is arranged on the thigh socket 11. This sensor device 40 is also coupled to the control device 50, which, in the illustrative embodiment shown, is integrated in the thigh socket 11. The control device 50 has an integrated energy storage unit, for example an accumulator or a battery. In the illustrative embodiment shown, the detection device 60 is formed as a multiplicity of implantable electrodes, that is to say at least two implantable electrodes, which are implanted at different sites in the muscles of the thigh. Muscle activities are detected via these implanted electrodes 60, either by the detection of an electrical potential or by the detection of pressures, temperatures, flow rates, influences of the optical behavior of components or similar. The data detected by the implant can be recorded via a coil arrangement 61, which is arranged on the thigh socket 11 or integrated therein, and transmitted to the control device 50. It is likewise possible that the detection device 60 is designed as a combination of implanted elements and a coil 61 or a plurality of coils 61, in order to detect muscle contractions and, in particular, muscle co-contractions through the inductive effects that occurring in muscle contractions.

[0040] Arranged at the distal end of the prosthesis socket 11 is an interface 51 to the joint device 20, via which interface 51 it is possible to transmit the sensor data concerning the muscle co-contractions and, if appropriate, the sensor data from the sensor 40 on the thigh socket 11 to the actuator 30. The sensor data of the sensor 40 on the distal prosthesis component 22 are also transmitted to the control device 50 via the interface 51. The actuator 30 is then actuated and influenced depending on the presence of muscle co-contractions, for example by adjusting valves, throttle cross sections, by activating an electromagnet to influence magnetorheological fluids, by braking a motor and/or by activating a drive.

[0041] FIG. 3 shows a further variant of the invention with a basic structure corresponding to that of FIGS. 1 and 2. The thigh socket 11 is disassembled from the proximal component 21, and a mechanical connection of the thigh socket 11 to the joint device 20 can be effected via the pyramid adapter shown. In the illustrative embodiment according to FIG. 3, the detection device 60 is again designed as an implantable electrode arrangement with a coil 61. Alternatively or in addition, it is possible, as shown in FIG. 1, to arrange surface electrodes in recesses within the prosthesis socket 11 at predefined locations and to secure them via the belt 12 or fix them on the inner face of the prosthesis socket 11. By way of the belt 12, which can be designed as an elastic band, the electrodes are held at positions and pressed onto the surface of the skin with sufficient contact pressure. The thigh socket 11 itself is connected electrically conductively to the prosthetic joint 20 in order to transmit the data from the detection device 60 to the joint device 20 and in particular to the actuator 30.

[0042] As is shown in FIG. 2, the implanted electrodes 60 can be supplied inductively with energy via the coil 61 on or in the thigh socket 11 and are arranged such that they are located within the field of the coil 61 during use. The data transmission also takes place via the coil 61. According to the embodiment in FIG. 3, the detection device 60 is initially connected to a pre-processing unit 70, to which the raw data are transmitted from the electrodes 60. Instead of via implanted electrodes 60, this can also take place via surface electrodes according to FIG. 1. The raw data are processed in the pre-processing unit 70, for example in a data processing device or in a microcomputer which is arranged, with its own energy supply, in the pre-processing unit 70. The data are processed in a microcontroller, which can be arranged directly on the thigh socket 11, for example integrated in the distal connection piece of the thigh socket 11, in order to forward only the relevant or meaningful information. From the pre-processing unit 70, the processed data are transmitted to the prosthetic knee joint 20, for example via the data connection by means of the electrical coupling of the thigh socket 11 to the proximal prosthetic component 21. The processed raw data of the detection device 60 are transmitted to the control device 50, via which the impedance or the resistance or the drive of the actuator 30 is then controlled. Sensor data of the sensors 40 from the thigh and/or the lower part can also be transmitted to the control device.

[0043] The pre-processing unit 70 can be designed together with the detection device 60 as a module that can be arranged on an already existing prosthesis socket 11. In the case of implantable electrodes 60, the electrodes 60 are adapted for example to the coil 61 and the pre-processing unit 70 and have a modular structure.

[0044] The detection device 60, 61 and/or the pre-processing unit 70 can be designed to be able to be switched off, such that the prosthesis device 20 can also function without the control device 50 on the basis of the detected muscle co-contractions. The detection device and/or the pre-processing unit 70 are preferably designed to be plug-and-play capable, and therefore a complex coordination process between the individual components is no longer necessary.

[0045] The basic principle of the control is similar in all of the illustrative embodiments: the muscle activation is measured and detected via the detection device 60, such as the surface electrodes or implanted electrodes. A computing unit, either in the pre-processing unit 70 or in the control device 50, determines whether there is a muscle co-contraction. The intensity and the duration of the respective muscle contractions is determined. On the basis of the measured muscle contractions (it being possible to store in the control device 50 which simultaneous muscle contractions are regarded as muscle co-contractions), a control algorithm is used to establish whether and how the actuator 30 is activated or deactivated, i.e. whether a change in resistance is to be made or a movement is to be supported. The contraction signals are assigned when the control is set up and adapted to the user. Depending on the position of the respective detection device 60, it is possible to define which muscle or which muscle group causes the corresponding contraction signal.

[0046] If a pre-processing unit 70 is assigned to the control device 50 or to the actuator 30 or is connected upstream, the processed data, for example the co-contraction intensity and the duration of the muscle contractions, are transmitted to the joint device 20, such that the joint device 20 has available to it a signal that is easily processed and that can be easily integrated into the control process. As a result, the control effort is reduced and the operating time of the prosthetic device or orthotic device is prolonged, since the signal processing has no negative impact on the running time of the joint device 20 when it is used and, if appropriate, retrofitted with the detection device 60. Particularly if the pre-processing unit 70 can be retrofitted and has its own energy supply, the operating time of the prosthetic joint 20 is not negatively influenced. If appropriate, the total operating time of the orthotic or prosthetic device 10 can be prolonged by simply replacing the pre-processing unit 70 with its own energy supply.

[0047] FIG. 4 shows a schematic representation of the course of a movement resistance R and a flexion angle a over time, as a function of the detected muscle contraction signals. A step cycle is shown, starting with the heel strike and ending with the conclusion of the swing phase shortly before the heel touches down. The flexion angle a initially increases, that is to say the knee angle decreases. After the heel has touched down, a so-called stance phase flexion takes place in order to avoid force being transmitted through an extended leg, for example an extended prosthesis or orthosis. The impact movement is thus damped, and the artificial knee joint is allowed to bend slightly. After the foot or the prosthetic foot has been fully set down, a maximum extension takes place during the roll-over to the end of the stance phase, at which a flexion movement already begins, the maximum of which flexion movement is reached in the swing phase when the knee is bent to the maximum. There is then a reversal of movement and an extension of the knee joint. This is shown by the solid line. The resistance R to flexion when walking on a level surface rises to a high level after the heel strike, in order to prevent the knee from bending inadvertently. Even after reaching the roll-over and an onset of stance phase extension, the resistance R remains at a high level, in order then to drop to a low level when the forefoot is loaded, in order to permit flexion for initiating the swing phase. In the further course of walking, the flexion resistance R is increased in the swing phase so that the flexion is not carried out too far, such that an extension of the knee joint can be achieved at the end of the swing phase. Shortly before the reversal of movement is reached, the flexion resistance R is not increased further and, after the maximum flexion angle is reached, it is reduced to the level required for damping the movement during the stance phase flexion. An increased level of flexion damping at the end of the swing phase contributes to the safety of the user, so as to prevent inadvertent bending of the knee in the event of stumbling.

[0048] If, as is shown in the lower diagram in FIG. 4, a muscle co-contraction is detected, which can be seen from the high amplitude in both directions, the flexion resistance R is changed, namely increased in the illustrative embodiment shown, as is indicated by the dashed line. A co-contraction can occur involuntarily, for example, when an obstacle is felt or seen or a smooth surface is recognized. Then, when the foot or the prosthetic foot is set down, an increased resistance to bending of the knee joint is already provided, as a result of which the maximum attainable flexion angle a is reduced, which is likewise shown by the dashed line. In the illustrative embodiment shown, the movement influencing takes place through a stronger and earlier increase in the flexion damping in the stance phase flexion. The amount of movement, i.e. the maximum flexion angle a, is thus reduced, and the knee joint feels more compact and stiffer. In a co-contraction during the swing phase, the resistance R can likewise be increased earlier and more strongly, such that the flexion angle increases less quickly and the maximum swing phase flexion is also reduced. The knee joint swings less strongly and therefore comes to full extension much earlier and more quickly. This provides enhanced safety for the user.

[0049] A variant of the control method for walking downhill is shown in FIG. 5. Here too, the standard curve of the flexion damping R is shown with the solid line, the knee angle curve a without control via co-contractions is also shown with the solid line. In the standard method, the flexion damping R is increased with the bending in the stance phase until the flexion is blocked. There is then what is called a plateau phase, from which the flexion damping R is reduced to a high level in the middle stance phase, in order to permit further bending, but with a flatter increase in the flexion angle, in order to permit a residual swing phase after heel detachment and relief of the prosthesis and to prepare for the next heel strike. If muscle co-contractions are determined, as shown in the lower diagram in FIG. 5, these resistances can accordingly be increased earlier or maintained at a higher level for longer, such that the knee joint bends later or more slowly and, overall, a higher level of damping against flexion is provided.

[0050] In addition to the above-described embodiments of the control of the movement behavior via modified damping, it is possible to influence the movement behavior via other actuators or resistance devices. The ability of a system to counteract a force with a movement is seen as movement influence. This can be done by mechanical elements such as spring elements with a defined stiffness and zero point, damping elements acting in proportion to speed, friction elements and/or masses. Likewise, the movement can be influenced via a motor, a hydraulic or pneumatic damper, spring elements, piezoelectric elements, hydraulic or pneumatic drives or combinations of the stated elements or components. Active drives offer a maximum degree of influence; for example, an electric motor can simulate an elastic behavior and influence the perceived inertia of the joint or of the prosthetic or orthotic device and generate a speed-dependent force.

[0051] Examples of situations for voluntary or involuntary co-contractions are shown in FIG. 6, for example when an obstacle appears, when a danger from animals, people or machines is perceived, on smooth surfaces, in the event of sudden dangerous situations, or in unsafe or dangerous environmental conditions. The reflexive muscle co-contraction and also the conscious muscle co-contraction make it possible to influence a control method by muscle activation, wherein a basic pattern of the control method is preferably retained, and only the expressions in terms of strength and duration are changed or influenced. In particular, influencing the movement behavior via muscle co-contractions has the advantage that this can take place both consciously and unconsciously, as a result of which the reflexes of the human being in the perception of the environment can advantageously be utilized to control the orthotic or prosthetic device.

[0052] FIG. 7 shows a schematic representation of a resistance curved R plotted over time. If, for example, a co-contraction is determined which appears to make it necessary to increase the resistance to bending, this resistance R is increased very quickly, starting from a basic resistance. After a maximum of the resistance has been reached, for example after the co-contraction has subsided or upon detection of a circumstance that causes the control to reduce the resistance again, a slow reduction in the resistance R is first of all carried out, such that the resistance decreases gently over time. This prevents a rapid drop in resistance from leading to a loss of balance and to unsafe situations for the user.