Method for controlling an artificial knee joint

Abstract

The invention relates to a method for controlling an artificial knee joint (1), said artificial knee joint having: an upper component (10) with a front side (11) and a rear side (12); a lower component (20) pivotably supported about a knee axis (15) on the upper component (10), the lower component having a front side (21) and a rear side (22); a foot component (30) arranged on the lower component (20); at least one sensor (25, 51, 52, 53, 54); a control device (60) connected to the at least one sensor (25, 51, 52, 53, 54); and an actuator (40), the actuator being coupled to the control device (60) and the knee angle (KA max ) that can be achieved between the rear side (12) of the upper component (10) and the rear side (22) of the lower component (20) during the swing phase being adjustable via the actuator by the control device, and inferring, from the sensor data of the at least one sensor (25, 51, 52, 53, 54), the height difference (ΔH) between the foot component (30) and the opposite foot (33) of the patient or the height difference from the immediately preceding stance phase of the foot component (30) when walking, and adjusting the knee angle (KA max ) that can be achieved during the swing phase.

Description

Field of the Invention

[0001] The present invention relates to a method for controlling an artificial knee joint, the artificial knee joint having: an upper component with a front side and a rear side; a lower component pivotally supported on the upper component about a knee axis, the lower component having a front side and a rear side; a foot component arranged on the lower component; and an actuator by means of which the knee angle achievable between the rear side of the upper component and the rear side of the lower component at the end of the swing phase can be adjusted. Background Art

[0002] Artificial knee joints are used in prostheses, orthoses, and exoskeletons. The artificial knee joint has an upper component and a lower component which are pivotally supported relative to one another about a knee axis. In the simplest case, the knee joint is constructed as a monoaxial knee joint, in which, for example, a bolt or two support sites arranged on the swing axis form a single knee axis. There are also knee joints which do not have a fixed axis of rotation of the upper component relative to the lower component, but rather have sliding or rolling surfaces or a plurality of guide rods articulated to one another. In the prior art, so-called four-axis knee joints with spring devices and dampers are relatively commonly described. In addition, there are five-axis and six-axis knee joints. In orthoses and exoskeletons, a multi-axis configuration of the artificial knee joint is the exception.

[0003] A prosthetic knee joint is usually manufactured and provided as a complete assembly which has connection means for fixing a thigh tube or other means for fixing the upper component to the patient and fixing means for fixing the lower component (for example, a calf tube or a prosthetic foot). In orthoses and exoskeletons, the fixing means for fixing the artificial knee joint to the patient can be arranged directly on the upper component and the lower component, for example in the form of belts, collars, or shells arranged on rails or an external frame structure.

[0004] In order to influence the extension movement and / or the flexion movement, it is known to arrange an actuator between the upper component and the lower component, for example in the form of a damper or a drive device.

[0005] DE 10 2013 011 080 A1 relates to a method for controlling an orthopedic joint device for the lower extremities, the joint device having an upper part and a lower part pivotally supported on the upper part, with a conversion device arranged between the upper part and the lower part, by means of which mechanical work is converted from the relative movement during the swinging of the upper part relative to the lower part and stored in at least one energy accumulator. The energy is in turn fed to the articulation device at staggered times in order to support the relative movement, wherein the stored energy is inverted and the delivery of mechanical work is controlled during the support of the relative movement. In addition to the conversion device, a separate damper in the form of a hydraulic or pneumatic damper can be provided, which is constructed in an adjustable manner, so that the resistance during walking can be influenced by the damper device not only in the flexion direction but also in the extension direction.

[0006] US 5,181,931 relates to a swing connection device between two parts of an orthopedic device, the orthopedic device having an upper part, a lower part and an adjustable mechanical extension stop.

[0007] EP 2 240 124 B1 relates to an orthopedic knee joint, which has: an upper part on which an upper connecting device is arranged; a lower part pivotally supported on the upper part, the lower part having a connecting device for an orthopedic component; and a stop for limiting the extension movement. The stop is constructed to be displaceable and coupled to an adjustment device, which in turn is coupled to a control device, which actuates the adjustment device based on sensor data and changes the position of the stop such that the extension stop for walking is shifted forward and retracted for standing.

[0008] The artificial knee joint has a knee angle of 180° in the maximum extension that can be achieved in the structure, and hyperextension (i.e., the angle on the rear side is greater than 180°) is usually not set. The backward swinging of the lower part relative to the upper part is called knee flexion, and the forward swinging is called extension. During the initial contact, the foot touches the ground at the end of the swing phase and at the beginning of the stance phase. When walking in a plane, heel strikes will mostly occur, that is, the foot first touches the ground with the heel. If the artificial knee joint is kept in a stretched straight position, this leads to direct force conduction into the pelvis, which is felt to be very uncomfortable. Therefore, similar to natural walking, the so-called stance phase flexion is allowed or performed in the prosthesis or orthosis, in which the knee joint bends around the knee axis after the heel strike, and if necessary, bends against the resistance caused by the hydraulic damper. The artificial knee joint can be stopped at a certain knee angle at the end of the swing phase by the extension stop, so as to introduce the stance phase flexion or help it to be introduced. The extension stop is set so that at the initial landing at the end of the swing phase, there is no fully extended leg, i.e., the maximum knee angle set in the structure is not set, but the achievable knee angle is reduced, which is called flexion and has a positive effect on the walking behavior because it allows a more uniform walking. Typical values ​​for the extension stop for walking on a flat surface are at a knee angle of approximately 176°.

[0009] In walking situations that differ from walking on a flat surface, a control adapted to walking on a flat surface is often not sufficient and in these special situations would hinder the user. Summary of the invention

[0010] The object of the present invention is to provide a method with which users of artificial knee joints can better understand the special circumstances of walking.

[0011] According to the invention, this object is achieved by a method having the features of the independent claim. Advantageous embodiments and developments of the invention are disclosed in the dependent claims, the description and the drawings.

[0012] According to the method for controlling an artificial knee joint of the present invention, the artificial knee joint comprises: an upper part with a front side and a rear side; a lower part pivotally supported on the upper part about a knee axis, the lower part having a front side; a foot part arranged on the lower part; at least one sensor; a control device connected to the at least one sensor; and an actuator, which is coupled to the control device and by which an achievable knee angle between the rear side of the upper part and the rear side of the lower part at the end of a swing phase can be adjusted. The method proposes to infer from sensor data of at least one sensor how to overcome a height difference between the foot part and the patient's opposite foot or the foot part or a height difference with the foot part in an immediately preceding standing phase during a standing phase of the patient, and in particular to adjust the achievable knee angle during the swing phase based on a height difference preferably determined or estimated during the swing phase. The achievable knee angle, in particular the achievable knee angle in the swing phase extension, differs from the structurally maximum knee angle in that the achievable knee angle is set by an actuator and is variable, whereas the structurally maximum knee angle generally means an extended, maximally extended leg with a knee angle of 180°. The structurally maximum knee angle is predetermined by the design and arrangement of the components of the artificial knee joint.

[0013] Overcoming a height difference can be, on the one hand, going up a slope, going up stairs or, on the other hand, overcoming a physical height difference. However, it is also possible that the user intends to position the foot accordingly without there being a physical slope or height difference. Going up stairs can be overcoming one or more steps and / or bosses. This can be ascending a boss, for example overcoming a curb, but can also be ascending a staircase, i.e. a plurality of successive steps.

[0014] The setting of the extension stop is as follows: at the end of the swing phase, when the initial contact, for example the initial heel strike, there is no fully extended leg, that is, it is not set to the knee angle that is set at the maximum in the structure, but the knee angle that can be achieved is reduced to provide the so-called forward flexion, which has a positive effect on the walking behavior, because it can achieve uniform walking. Other overcoming height differences intended by users of uphill or stairs or artificial knee joints are different from the walking behavior in a plane. In normal walking in a plane, the contralateral and ipsilateral feet have the same vertical spacing with the hip during the initial step. On the contrary, when overcoming the height difference, the vertical spacing of the leading foot and the hip must be shortened to compensate for the height difference. In physiological walking, this is achieved by introducing a strong hip flexion on one side of the leading leg and landing the leg in a corresponding forward bent position. In addition, especially when the height difference is large and the step length is small, the body center of gravity is first left on the standing leg, and the weight is only transferred when the leading foot initially lands. When walking on a flat surface, the stride length of the conditioned leg, i.e. the leg equipped with an artificial knee joint (which may be a prosthesis, orthosis or exoskeleton), is equal to the stride length of the unconditioned leg. When walking on a flat surface, the body center of gravity moves substantially evenly between the standing leg and the swinging leg.

[0015] When the user intends to go uphill or upstairs or when overcoming other height differences during walking, the center of gravity or pelvis moves unevenly forward. More precisely, the user of the artificial knee stands on the rear leg, and the rear leg can hardly contribute to the so-called step forward (Schrittvorlage). Almost the entire step forward is performed by the leg (i.e., the leg that is lifted and is to or should land at a level higher than the standing leg) during the swing phase. The achievable knee angle of the artificial knee is adjusted according to the determined or estimated height difference between the foot component on the cared side (i.e., the side with the artificial knee) and the opposite foot or foot component of the patient during the standing phase. It has been shown that when there is stronger forward flexion compared to walking on flat ground and thus a smaller achievable knee angle, going uphill and upstairs is basically made easier. In contrast to landing with an extended or only slightly forward-flexed knee joint, when landing with a strongly forward-flexed joint at the same height difference, the horizontal force arm between the force application point on the foot and the hip is shortened, and the necessary hip extension moment around the body's center of gravity is also brought about by the cared leg. The body's center of gravity does not have to be leveraged over the entire length of the extended leg, but only has to be leveraged with a smaller force arm due to the shortened leg length. Thus, a generally harmonious movement can be achieved when going uphill or upstairs. The load compensation mechanisms, such as increased plantar flexion of the foot on the standing leg side or increased forward inclination of the upper body, can be reduced. The step length is in a better relationship with the opposite side, making the gait more symmetrical and natural. When caring for the passive foot and foot component, the foot also lands on the ground in a more favorable orientation. Advantageously, the achievable knee angle is reduced by 5° to 30° relative to the structurally maximum set angle. Especially in combination with a movable ankle joint, such as the matching of the ankle angle and the ground inclination, but also when actively supporting the extension movement during the standing phase, the achievable knee angle can be advantageously reduced beyond this range, especially when overcoming particularly large height differences.

[0016] The uphill, upstairs or the user's intention to overcome other height differences can be inferred from the determined or estimated height difference. Preferably, the height difference between the foot or foot component of the opposite leg and the leading foot or foot component in the swing phase is considered for control. Another possibility is to consider the height difference overcome by the ipsilateral foot during the swing phase.

[0017] The achievable knee angles, especially the knee angles achievable during the swing phase extension, can in particular be matched during the swing phase of a step. Thus, it is preferably matched in such a way that the achievable knee angles are coordinated with the subsequent initial contact and / or the subsequent stance phase. However, it can also be that the achievable knee angles have been adjusted in the previous stance phase or the previous step, in particular when the intention to climb uphill, upstairs and / or overcome a height difference has been recognized in the previous step, and based on this information, the achievable knee angles are matched for the subsequent step. For example, it can also be that the achievable knee angles are only adjusted when the intention to climb uphill, upstairs and / or overcome a height difference is recognized for a plurality of successive steps. In addition, it can be that the achievable knee angles remain unchanged over a plurality of successive steps, for example when a plurality of successive steps are taken uphill, and are only adjusted when a deviating situation is recognized.

[0018] In the terminal stance phase, knee flexion can be allowed with low flexion resistance and / or knee flexion can in particular be introduced based on sensor data that allows conclusions to be drawn about overcoming a height difference, wherein the achievable knee angles in the swing phase are adjusted.

[0019] An improvement of the invention provides that, when climbing upwards, i.e. when increasing the height difference against the direction of gravity, the achievable knee angles are reduced. The greater the height difference between the foot of the standing leg and the foot of the moving leg, the smaller the achievable knee angles are set. Thus, in the case of higher steps or on steeper terrain, the extension stops earlier. Conversely, this means that in the case of gentle steps or small slopes, the achievable knee angles are not reduced as strongly, thus enabling easy forward movement. The matching of the achievable knee angles to the height difference can be carried out continuously and / or in a plurality of discrete steps. In addition, it is feasible that the achievable knee angles no longer decrease from a certain height difference. In particular, by matching the knee angles to the height difference and / or the step height, the load on the cared-for or ipsilateral side of the user of the artificial knee joint is reduced, and generally the artificial knee joint cannot provide the full functional capacity of the leg muscle tissue.

[0020] The height difference to be overcome, as a characteristic parameter of the achievable knee angle, can be detected and / or determined by the trajectories of the corresponding ipsilateral hip joint, knee axis, and / or foot component. The trajectory describes here the curve of the change in the position of points in space over time. The translational displacement of a point connected to the artificial joint and located, for example, on the upper component, lower component, or knee axis, and thus also the vertical component, such as the acceleration value that can be determined therefrom, are determined by means of double integration. The initial conditions of the integration are determined, for example, by a kinematic model, where the start of the integration is advantageously in a late stance phase. The segment lengths required for the kinematic model can be measured and stored in the control device required for calculating the control signals for the actuator. Through the kinematic chain, the trajectory curve of one point can be inferred from that of another point via the relative degrees of freedom and segment lengths, such as the trajectory curves of the hip, knee axis, or foot component. The degrees of freedom and segment lengths are known or stored in the control device, so that movement data or other data of the un-cared-for contralateral leg do not have to be used for determination. For example, the acceleration and orientation of the lower component are determined by an acceleration sensor, the angle between the lower component and the upper component is determined by a knee angle sensor, and the trajectory, speed, and acceleration of the hip are determined by the integration of the acceleration data and the kinematic chain. As an indication of overcoming the height difference, in particular, speed and acceleration can be considered, preferably the vertical component. When overcoming the height difference, on the one hand, the center of gravity of the body and thus the hip are lifted. On the other hand, the knee moves forward and upward particularly quickly. Alternatively or additionally, the displacement, speed, and / or acceleration experienced by one or more points of the lower component and / or the knee axis can be considered, in particular the relationship between the horizontal and vertical components, to infer the overcoming of the height difference.

[0021] Since it can be assumed that during the contralateral stance phase, when the foot is on the ground, the speed there is 0, in particular the horizontal speed component is 0, the trajectory of the hip can alternatively or additionally be determined from one or more angle measurements on the contralateral side and the known segment lengths. Then, the overall hip forward movement and hip lift can be calculated from the angle measurements and the known leg length on the contralateral side.

[0022] The height difference between the contralateral foot during the stance phase and the ipsilateral foot or foot component during the swing phase can be calculated or estimated by the vertical displacement of the hip joint of the cared-for ipsilateral leg, the vertical displacement of the knee axis, and / or the vertical displacement of the foot component, and used as a characteristic parameter of the achievable knee angle. The vertical displacement of the hip joint of the cared-for leg can be determined, for example, from the acceleration value determined for a point fixedly connected to the position of the artificial knee joint, which point is located, for example, on the upper component, lower component, or knee axis as described above. The trajectory curve of this point can be determined by double integration. Through the kinematic chain, the trajectory curve of the hip joint can thus be determined as a function of the relative degrees of freedom and segment lengths.

[0023] The degrees of freedom and the segment lengths are known, stored, and available in the control device, so that the vertical displacement of the hip joint can be calculated therefrom without using the movement data or other data of the uninjured contralateral leg. The vertical displacement of the knee axis can be determined by double integration of the acceleration of a fixed point on the artificial knee joint or a component arranged thereon (such as the prosthetic socket), as described above, and the same applies to the vertical displacement of the foot component.

[0024] The movement of the hip and / or the trunk can also be directly determined by sensors, such as inertial sensors that detect acceleration, which are mounted on the hip or the trunk. The speed and trajectory can be calculated from the acceleration by double integration.

[0025] An improvement of the invention provides that, as a characteristic parameter for the achievable knee angle, the height difference is determined from the hip angle of the injured leg or the orientation of the upper component in space, and, if necessary, its time course. Inertial angle sensors can be arranged on the upper component for the orientation of the upper component in space, so that the spatial orientation of the upper component can be directly measured. Thus, for example, inertial angle sensors or IMUs (inertial measurement units) can be arranged in or on the artificial knee joint. Usually, knee angle sensors are also arranged on the prosthetic knee joint or other artificial knee joints, so that the hip angle and the orientation of the upper component in space can be jointly calculated from the orientation of the lower component in space and the knee angle. The orientation in space is the orientation relative to a substantially unchangeable reference direction, such as the direction of gravity or the horizontal line. For this purpose, no sensors are required on the uninjured side of the patient's contralateral side.

[0026] The hip angle can be directly measured as the relative angle between the trunk and the upper component or the thigh. Alternatively, the orientation of the trunk in space can be assumed or measured with the aid of an IMU, and the hip angle can be determined together with the orientation of the upper component or the thigh. In particular, the course of the hip angle and / or the symmetry of the orientation of the upper component relative to the vertical neutral position (such as a proportional relationship or a difference), the swept angle range, and / or a high flexion speed can be considered as indications for detecting and / or determining the height difference to be overcome. If the upper component is guided into a strong flexion, a large angle range is swept, and / or a particularly fast hip flexion is achieved, a height difference against gravity can be assumed. Here, the thresholds and parameters for identification can be related to the walking speed in order to distinguish the influence of the walking speed on the angular course over time from each height difference to be overcome.

[0027] An improved embodiment of the method provides that the height difference to be overcome between the leg to be cared for and the non-care leg is detected, calculated, and / or estimated from the relationship between the translational horizontal movement of the hip joint or the knee axis of the leg to be cared for and the hip angle or the orientation of the upper component in space. To calculate the height difference, the translational movement of a point on the prosthesis or orthosis, such as the movement of the knee axis, can be calculated, for example, by double-integrating the measured linear acceleration with suitable initial conditions and through the kinematic chain up to the absolute and relative angles of the hip. The initial conditions of the integration are determined by the kinematic model, where the start of the integration advantageously occurs in the late stance phase. In the assumed pure rigid body movement, for example, the rolling point on the foot component and its time curve can also be expressed as a function of the load and orientation or position. The segment lengths required for the kinematic model can be measured and stored in the control device required for calculating the control signals for the actuators. The translational movement of the hip or the horizontal movement of the hip joint can be used to evaluate this movement and draw conclusions about the walking behavior and walking conditions. The horizontal component of the hip movement represents the share of the forward progression generated by the standing leg. The hip angle or the orientation of the upper component controls the positioning on the swing leg side. The two aspects of the movement cooperate with each other and are thus suitable for identifying whether going uphill or upstairs. Due to the cooperation of the movements of the standing leg and the swing leg, the swing leg movement to be achieved by the leg to be cared for can be inferred. If the upper component bends particularly strongly or quickly relative to the horizontal movement of the hip, it can be inferred that a height difference against gravity is being overcome. Alternatively, the relationship between the horizontal hip movement and the horizontal knee movement, as well as the relationship between the horizontal knee movement and the orientation of the upper component or the hip angle, can also be considered. Here, all parameters can be derived entirely from the sensor data on the cared-for side.

[0028] An improved embodiment of the present invention provides that the height difference is obtained or estimated from the obtained knee angle (e.g., by direct measurement by a knee angle sensor) and / or from the relationship between the spatial orientations of the upper component and / or the lower component or the thigh and / or the calf. As long as the hip angle is provided, it can be considered for calculating the height difference. The hip angle can be calculated or estimated from the assumed orientation of the upper body and the orientation of the upper component or the thigh part in space obtained by the IMU, or obtained by combining the spatial orientation sensors on the upper body, such as on the orthosis or exoskeleton, with the orientation of the upper component from the IMU. The height difference can be obtained or estimated from the time curve, the relationship between the knee angle and the orientation of the upper component or the lower component, and / or the relationship between the orientations of the upper component and the lower component relative to each other. The time curve and the relative movement of the segments, such as particularly rapid, significant, or continuous bending or vibration, give conclusions about the user's intention and the height difference to be overcome. Thereby, it can be identified in the swing phase whether going uphill, upstairs, or other height differences are being overcome, so that in particular, the achievable knee angle can be determined and adjusted in the swing phase.

[0029] The achievable knee angle can be adjusted by an adjustable mechanical extension stop. The mechanical stop can be adjusted by different actuators, such as by a motor-driven end stop, by the torsion of an eccentric, by the longitudinal movement of the stop, by hardening a buffer or otherwise. It can also be that the extension stop is adjusted hydraulically or pneumatically in such a way that, depending on the achieved knee angle, a valve is closed so that no fluid can flow from the extension chamber into the flexion chamber or the compensation container. It can also be that the extension stop is hardened by hardening a cushion, for example by filling a stop damper with hydraulic or pneumatic fluid. The stop can be formed by a locking drive (such as a motor), where the adjustment is carried out by locking the motor after the desired knee angle has been reached. Alternatively, the adjustment of the extension stop can be achieved by the activation or deactivation of magnetorheological fluid and a magnetic field. When applying functional electrical stimulation, the stop can be achieved by activating the knee flexor muscle tissue. In all the methods mentioned, it is not necessarily required to create a physical obstacle in the extension direction. It is sufficient to stop the extension movement at and / or before the desired knee angle and / or to decelerate it in such a way that the achievable knee angle is not exceeded, for example by predictive regulation. With the aid of the actuator, the resistance of the knee joint against flexion or extension can also be controlled in order to achieve a controlled extension movement and / or flexion movement. In addition, the joint can be actively extended and / or flexed with the aid of an actuator (such as a motor, pump, spring, spring reservoir), by electrical stimulation or by other actuators capable of generating movement against a force, in particular to achieve the desired degree of knee flexion at the end of the swing phase.

[0030] An improvement of the invention provides that another characteristic parameter for the achievable knee angle is the orientation of the lower component in space. During physiological stair climbing or uphill walking, the lower leg remains within a relatively narrow angle range relative to the vertical line at the end of the swing phase and at initial contact. Therefore, the achievable knee angle can be matched such that a defined orientation of the lower component is achieved at the end of the swing phase and / or at initial contact during uphill walking or stair climbing or when overcoming an obstacle or a height difference. In addition, it can be inferred from the orientation of the lower leg at initial contact that uphill walking or stair climbing or the overcoming of an obstacle or a height difference has occurred. The orientation of the upper component in space at initial contact depends on the step height to be achieved, while the orientation of the lower component in space only changes slightly. Based on the determined step height, the orientation of the lower component to be achieved at initial contact can be predefined, and the corresponding achievable or to-be-achieved knee angle can be calculated based on the orientation of the upper component.

[0031] ​In addition to the step height, the orientation to be achieved of the lower part can also depend on the walking speed and / or step length. The hip torque introduced by the user, the forward inclination of the leading leg, the duration of the step, and the force application point on the prosthetic foot or foot part and / or its time variation curve change with the walking speed and step length. Therefore, it is advantageous to match the achievable knee angle accordingly. It is particularly advantageous to reduce the achievable knee angle at a lower walking speed. The walking speed and step length can be obtained through sensor data, especially through an inertial sensor, which detects the orientation of the segment in space and its change over time and acceleration. The speed and position can be obtained by integration from the acceleration. In particular, the step length can be derived from the horizontal movement of the hip and / or knee axis. Alternatively or in addition, the step length can be derived from the forward inclination of the leg being cared for at the end of the terminal standing phase.

[0032] A further development of the method provides that the height difference is determined or estimated from the knee angle measured by a knee angle sensor on the artificial knee joint and the spatial orientation of the upper or lower part measured by a spatial orientation sensor arranged on the artificial knee joint. This makes it possible to detect whether an uphill climb or a staircase climb is taking place during the swing phase, so that an increased forward flexion and a reduced achievable knee angle can already be determined and set during the swing phase. The height difference can be determined from three characteristic variables, namely the knee angle, the spatial orientation of the upper part and the spatial orientation of the lower part, or alternatively from two of the three characteristic variables, for example from the two spatial orientations or the knee angle in combination with the spatial orientation of the upper or lower part.

[0033] A further development of the invention provides that during the swing phase of the treated ipsilateral leg, the achievable knee angle is set and maintained until: a predetermined spatial orientation and / or movement of the lower part and / or upper part, a predetermined rotation and / or rotation speed of the lower part and / or upper part in space, an ankle joint angle, a predetermined force introduction point in the foot part, a predetermined force on the foot part, a predetermined moment acting on the foot part, the knee axis or the hip axis, the orientation of the ground reaction force vector, a defined acceleration on the foot part, and / or the knee angle is maintained for a predetermined period of time. Only after reaching, for example, a predetermined spatial orientation or rotation of the lower part and thus of the lower leg, in particular after a reversal of the lower leg movement, and / or after a sufficiently reduced backward tilting of the lower leg compared to the end of the swing phase, can it be concluded that sufficient load and rolling motion have occurred, so that the achievable knee angle can be increased and the knee joint can be allowed to extend further. For example, the maintenance of the maximum knee angle can be controlled when the spatial orientation of the lower part or the lower leg is changed after ground contact. If, after the foot part has come into contact with the ground, it is detected, for example by a spatial orientation sensor, that the lower part or the lower leg is rotated forward by a certain angle, for example 5°, the locking of the knee joint can be released and extension can be allowed.

[0034] Similar situations apply to the upper part, which reaches a certain orientation in space at the end of a step cycle of going uphill or upstairs at the end of the hip flexion phase. Data about rolling characteristics, local ground slope and the positioning of the center of gravity above the ankle joint can be obtained about the ankle angle, so that conclusions about the step change curve can be inferred. Instead of an angle sensor, a force sensor can be arranged on or in the foot part and the lower part, and the force sensor obtains the position of the force introduction point in the foot part and the orientation and size of the ground reaction force. Through the change curve of the force introduction and ground reaction force from the heel impact to the forefoot load, or during the initial contact on the forefoot during the rolling movement, the progress of the movement and the corresponding stage occupied can be obtained or estimated. The impact of the initial contact can be obtained by the acceleration sensor on the foot part and / or the lower part and the landing of the foot can be inferred from it. In addition, from the hip joint torque, especially from the extension torque, the forward movement to be achieved can be inferred, and the knee extension is allowed. In particular, it can be that the reduced knee angle is maintained in the load transfer phase and / or the early rolling phase.

[0035] Alternatively or in addition, the extension stop can be changed after a predetermined time in order to provide increased safety by increasing the extension movement of the knee joint. It is assumed that after a certain time has passed, either a movement progression or a change in the movement pattern occurs, so that an increased safety is desired by an extended knee joint. For example, a user of an artificial knee joint is able to stop on a step or pause when going uphill, for which purpose, for example, a knee joint with maximum extension is advantageous.

[0036] A further development of the invention provides that a knee extension movement is allowed in the stance phase following the swing phase. The extension movement can be controlled according to the knee angle and / or knee angular velocity, the orientation of the upper part and / or the lower part in space, the ankle angle and / or the position, orientation and magnitude of the ground reaction force. A constant extension resistance or a resistance coupled to the knee angle can be set during the knee extension movement. The level and variation curve of the extension resistance can depend on the step height, step length, walking speed, knee bending and / or the force application point on the foot when the foot lands and / or the local ground inclination. In particular, during the rolling and knee extension movement, the resistance against knee extension can be increased decreasingly, linearly or incrementally. The extension movement can also be controlled so that the knee extension speed is controlled, in particular kept constant or does not exceed a predefined value. Alternatively, the extension movement can be controlled so that the lower part has an almost constant orientation during knee extension, and the thigh rolls about the knee axis as a result, and the backward rotation of the lower part is limited or a defined forward rotation of the lower part is achieved. In physiological walking, a slight forward rotation of the lower leg usually occurs. Due to the characteristics of the foot or foot parts that are different from physiological walking, such as the lack of the possibility of dorsiflexion, it can be meaningful to realize a variation curve for the movement of the lower part that is different from a slow forward rotation (for example, a nearly stationary lower part) in contrast to physiological walking. The force application point on the foot can be determined by a force sensor and the extension movement can be controlled so that the force application point is controlled during the extension movement, preferably kept in the middle area of ​​the foot and not moved in the direction of the heel or moved too early in the direction of the toes. Here, a faster knee extension causes the force application point to move in the direction of the heel and less quickly in the direction of the forefoot, and a slower knee extension causes the application point to move in the direction of the forefoot. When the foot lands on the forefoot, due to the larger force arm of the ground reaction force around the knee axis, a higher extension resistance is advantageously provided compared to when the heel lands. When the walking speed is high and / or the knee angle is small when the foot lands, it is practical to achieve a faster extension of the knee joint so that the foot performs an optimal rolling movement. The local ground slope can be determined by the ankle joint angle, based on which the control of the extension movement can be adapted. The extension stop at the end of the extension in the stance phase is advantageously configured so that the extension movement is gently braked. In the active knee joint, the extension movement can be actively supported. The user can adapt the control parameters via an interface and thus influence the behavior of the extension in the stance phase. The extension behavior can also be adapted by step-by-step control to suit the user's sporting style, the characteristics of the foot and / or the shoe.

[0037] An improved scheme of the present invention provides that after reaching the minimum hip angle and the reversal of the movement of the thigh, that is, after increasing the hip angle, the orientation of the lower part in space remains constant until the initial contact, the axial force acting on the lower part and / or the change of the ankle angle are detected. The initial contact can occur, for example, when the foot touches the ground or collides with an object or obstacle and is detected by a change in the movement characteristics, for example, by detecting the acceleration characteristics. If the foot part of the leg being cared for is lowered after the maximum hip flexion, the orientation of the lower part in space can be kept constant, for example, perpendicular to or parallel to the vertical line, by matching the extension resistance and the flexion resistance or by an active system with a drive device, until, for example, landing or rolling is detected. For example, landing can be detected by detecting the axial force or torque on the lower part, the acceleration of the lower part or the time variation curve of the hip angle. The pause in the descending movement can be concluded that the foot touches the ground and the patient is lifted to the next step by the leg being cared for. In addition to the orientation of the lower part, after reaching the minimum hip angle, the orientation of the connecting line of the hip to the foot or foot part (leg chord) in space can be controlled (in particular kept constant) until the foot touches the ground. If the hip extension is performed after the reversal of the movement of the thigh, the orientation of the leg chord can be kept constant, for example, by actively extending the knee joint via an actuator. During the hip extension, the knee angle can also be controlled so that the foot or foot part remains at the same or approximately the same horizontal distance from the hip, that is, the step length is kept constant during the descending movement.

[0038] The knee angle, the orientation of the lower part and / or the orientation of the leg chord can also be controlled as a function of the translational hip movement, in particular the horizontal hip movement, preferably so that the movement of the swinging leg is in a harmonious relationship with the movement of the stance leg. For example, the knee angle can be increased when the hip moves strongly forward. It is also possible that, after reaching the first maximum hip flexion, the hip is brought back into strong flexion, so that the knee extension is achieved, i.e. the stride on the swinging leg side is extended forward in the later swing phase.

[0039] A further development of the invention provides that climbing a slope, stairs or the like is detected by the time profile of the orientation of the upper part and / or the relationship between the orientation of the upper part and the translational horizontal movement of the knee axis, and the achievable knee angle is adjusted based on the profile and / or the relationship between the orientation of the upper part and the movement of the knee axis. The horizontal movement of the knee axis can be calculated based on the known upper part or thigh length and the time profile of the orientation of the upper part together with the horizontal movement of the hip axis.

[0040] One improvement of the invention provides that during the swinging phase of the leg being cared for, after the reversal of the direction of movement of the lower part, i.e. the knee movement, the flexion resistance is set to a level higher than when walking in a plane. During the swinging phase of the leg being cared for, a flexion movement occurs first, i.e. a reduction in the knee angle. If the lower part or the lower leg is brought forward, i.e. after the knee axis is raised to a higher level, and the knee movement changes from flexion to extension, it is advantageous for safety reasons to provide a resistance to the flexion movement, so that, for example, tripping is avoided when hitting obstacles or stair steps and in particular, an undesired bending of the knee joint about the knee axis is prevented.

[0041] Advantageously, when an uphill climb or stair climbing or the like is detected, the knee angle can be reduced by 5° to 20° during the swing phase in order to define a minimum achievable knee angle.

[0042] A further development of the invention provides that when an uphill climb or stairs or the like is detected, the minimum achievable knee angle in the swing phase is reduced compared to walking on level ground. When walking on level ground, knee flexion is typically limited or reduced by resistance in the bending direction so that knee extension is achieved in a timely manner at the end of the swing phase. Due to the smaller minimum knee angle when walking uphill, stairs or the like, the lower part swings further up and approaches the upper part, thereby increasing the ground clearance when swinging under the body. For this purpose, it is advantageous to reduce the minimum knee angle when the height difference to be overcome increases. Typical reduction values ​​are between 5° and 20°.

[0043] An improved scheme of the present invention is provided: in the standing phase, preferably in the terminal standing phase, when going uphill, upstairs or intending to overcome the height difference, knee bending under low bending resistance and / or introduction of knee bending. In the standing phase and thus when the foot is in contact with the ground or under load, the introduction of knee bending corresponds to physiological walking, wherein the knee joint is bent before the foot part loses contact with the ground. Therefore, knee bending is typically introduced during the rolling movement of the foot part. The bending under full or partial load at the end of the standing phase is called the pre-swing phase or Pre-Swing. In order to enable the knee joint to be flexed simply, in the standing phase, preferably in the terminal standing phase, the movement resistance in the bending direction is reduced or maintained at a low level for this purpose. Alternatively, in the active knee joint, bending movement can be introduced and / or supported under load. Preferably, the reduction of the movement resistance in the bending direction or the introduction of the bending movement is achieved based on sensor data. The achievable knee angle, in particular the achievable knee angle in the swing phase extension, is further adapted so that it supports climbing uphill, stairs or overcoming height differences in the subsequent swing phase and / or in the subsequent stance phase. Advantageously, the user can maintain the natural movement sequence for inducing knee flexion and the swing phase and does not have to perform a special movement sequence for inducing knee flexion in the swing phase for climbing uphill, stairs or overcoming height differences.

[0044] An improved solution of the present invention provides that the achievable knee angle is adjusted during the swing phase when going uphill, up stairs or when attempting to overcome a height difference, wherein the user relieves the load on the prosthesis, orthosis or exoskeleton before initiating the knee flexion movement. For example, the introduction of knee flexion can be carried out in the following way: when the same side is relieved of load and / or after it is relieved of load, the knee joint reduces the movement resistance in the bending direction, and the user performs hip flexion or a combination of hip extension and subsequent hip flexion. It is also possible that in order to reduce the movement resistance, further movements are required in addition to partial or complete loading, such as hip extension, in particular rapid hip extension. Another possibility is to support or actively introduce knee flexion in an active knee joint.

[0045] A refinement of the method provides that the knee angle to be achieved can be set consciously and independently of the determined or estimated height difference and / or can be varied over time. The user (e.g. an orthopedic technician, a therapist or an end user) can make adjustments to the control parameters via an interface. The user can set the achievable knee angle to be increased and / or reduced, for example manually by inputting corresponding values ​​or making corresponding adjustments. The user's settings can be superimposed on other control parameters, so that the control device also sets a smaller achievable knee angle, for example, in the case of a larger height difference, but in both cases a correspondingly larger achievable knee angle is set relative to the standard setting. It is also possible for the user to temporarily completely deactivate the reduced achievable knee angle.

[0046] It is also possible for the system to adapt or determine parameters for controlling the achievable knee angle based on walking data, either by a continuously automatically adapted adaptation or by an adjustment mode that is consciously activated and deactivated again after the adjustment has been made.

[0047] A further development of the invention provides that the height difference to be overcome is detected and / or determined by determining the distance to the ground and / or the contour of the ground. The ground and / or the distance to the ground can be measured contactlessly, for example by means of a sensor device fixed to the lower leg part and / or the foot part, in particular optically, by means of a laser radar, radar and / or infrared measurement and / or by means of an ultrasonic measurement. From the measurement of a plurality of points on the ground, the contour of the ground and from this the size of the height difference to be overcome can be inferred. Alternatively or in addition, the relative speed with respect to the ground can be measured, in particular by using the Doppler effect or by the time derivative of the determined distance. The knee angle to be achieved, in particular the knee angle to be achieved at the end of the swing phase, is set according to the determined height difference.

[0048] An improved scheme of the present invention is provided: in the swing phase, especially at the end of the swing phase and / or during the standing phase, especially during the initial contact and / or load response, the resistance against knee flexion is adjusted to a higher level than when walking in a plane. In the swing phase of the leg being cared for, flexion movement occurs first, i.e., a reduction in the knee angle. If knee extension occurs after the knee axis is raised to an increased level, it is advantageous to apply resistance to the flexion movement, which prevents the knee joint from bending undesirably around the knee axis. This is particularly advantageous in the following system, in which the resistance along the bending direction and the extension direction can be adjusted independently of each other. Otherwise, the flexion resistance can be increased when the maximum knee angle is reached, when the foot descends and / or at the initial contact, especially to a higher level than when walking in a plane. Here, the flexion resistance can be increased so that the flexion of the knee joint is completely suppressed.

[0049] The bending resistance at the initial contact can also be configured to allow controlled knee bending. In particular, the bending resistance is adapted so that the bending rate is controlled and / or the maximum bending angle is limited by the increase in the bending resistance. The knee bending can be controlled directly by the measured knee angle or by the measured orientation of the lower part in space, so that the forward tilting of the lower part reaches or does not exceed a defined value. The resistance level and the permissible degree of knee bending can also depend on the height difference to be overcome, the walking speed, the step length and / or the curve of the force application point on the foot during rolling, so that maximum safety and support are achieved in every case. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] An embodiment will be described in detail below with reference to the accompanying drawings. It shows:

[0051] Figure 1 Schematic diagram of a prosthetic leg;

[0052] Figure 2 Illustration of the different stages and situations when overcoming the height difference;

[0053] Figure 3 Angled illustration of the prosthesis being worn;

[0054] Figure 4 Flowchart of going uphill;

[0055] Figure 5 Flowchart of overcoming stairs

[0056] Figure 6 The trajectories of the ankle joint axis, knee joint axis, and femoral head during walking on level ground;

[0057] Figure 7 the trajectories of the ankle joint axis, knee joint axis, and femoral head during uphill climbing;

[0058] Figure 8a and 8b Graphic representation of height difference;

[0059] Figure 9 Graphic illustrations of different walking conditions;

[0060] Figure 10 Correlation between knee angle and height difference when going uphill;

[0061] Figure 11 Correlation of knee angle with height difference when overcoming steps;

[0062] Figure 12 Knee angle curves for different height differences over relative time;

[0063] Figure 13The changing curve of thigh orientation during a step cycle;

[0064] Figure 14 the relationship of thigh orientation to the horizontal displacement of the hip;

[0065] Figure 15 Possible auxiliary parameters for estimating step height;

[0066] Figure 16 Knee angle change curve KA in degrees during a walking cycle;

[0067] Figure 17 Different control curves for stretching during stance phase;

[0068] Figure 18 Two different knee angle curves during the walking cycle;

[0069] Figure 19 Resistance variation curve in passive control;

[0070] Figure 20 Figure 19 Variations of

[0071] Figure 21 The curve of the change of calf angle relative to thigh angle;

[0072] Figure 22 The curve of knee angle relative to thigh angle; and

[0073] Figure 23 Definition of leg string. DETAILED DESCRIPTION

[0074] Figure 1 A schematic diagram of an artificial knee joint 1 applied to a prosthetic leg is shown. Instead of being applied to a prosthetic leg, an artificial knee joint 1 of a corresponding configuration can also be used in an orthosis or exoskeleton. Instead of a substitute for a natural joint, the corresponding artificial knee joint is arranged in the middle and / or side of the natural joint. In the embodiment shown, the artificial knee joint 1 is constructed in the form of a prosthetic knee joint, which has an upper part 10 with a front side or a side 11 facing the walking direction or the front side and a rear side 12 opposite to the front side 11. A lower part 20 is supported on the upper part 10 so as to be pivotable around a pivot axis 15. The lower part 20 also has a front side 21 or a front side and a rear side 22. In the embodiment shown, the knee joint 1 is constructed as a monocentric knee joint. In principle, a polycentric knee joint can also be controlled accordingly. A foot part 30 is arranged at the distal end of the lower part 20 , which foot part can be connected as a rigid foot part 30 to an immovable foot joint or connected to the lower part via a pivot axis 35 in order to enable a movement sequence that approximates a natural movement sequence.

[0075] The knee angle KA is measured between the rear side 12 of the upper part 10 and the rear side 22 of the lower part 20. The knee angle KA can be measured directly by a knee angle sensor 25 which can be arranged in the region of the pivot axis 15. An inertial angle sensor 51 is arranged on the upper part 10, which measures the spatial orientation of the upper part 10, for example, relative to a constant force direction, for example a vertically downwardly directed gravity G. An inertial angle sensor 52 is likewise arranged on the lower part 20 in order to determine the spatial orientation of the lower part during use of the prosthetic leg.

[0076] In addition to the inertial angle sensor 53 , a force sensor or torque sensor 54 can be arranged on the lower part 20 or the foot part 30 , wherein the axial force FA acting on the lower part 20 can be ascertained.

[0077] An actuator 40 is arranged between the upper part 10 and the lower part 20 to influence the swinging movement of the lower part 20 relative to the upper part 10. The actuator 40 can be constructed as a passive damper, a drive device or a so-called semi-active actuator 40, with which kinetic energy can be stored and outputted in a targeted manner at a later time point to brake or support movement. The actuator 40 can be constructed as a linear or rotary actuator. The actuator 40 is connected to a control device 60, for example, by wired connection or by wireless connection, and the control device is coupled to at least one of the sensors 25, 51, 52, 53, 54. The control device 60 uses a processor, a computing unit or a computer of a computer to electronically process the signal transmitted by the sensor. The control device has an electric energy supply device and at least one storage unit, in which programs and data are stored, and in which a working memory is provided for processing data. After processing the sensor data, an activation or deactivation instruction is output, which is used to activate or deactivate the actuator 40. By activating the actuator 40 , for example, a valve can be opened or closed in order to change the damping characteristic.

[0078] A prosthesis socket is fixed to the upper part 10 of the prosthetic knee joint 1, which is used to receive the thigh stump. The prosthetic leg is connected to the hip joint via the thigh stump, and the hip joint angle HA is measured on the front side of the upper part 10, which is provided on the front side 11 between the vertical line through the hip joint and the longitudinal extension of the upper part 10 and the connecting line between the hip joint and the knee joint axis 15. If the thigh stump is raised and the hip joint is flexed, the hip angle HA decreases, for example when sitting down. Conversely, when extending, for example when standing up or similar movements, the hip angle HA increases.

[0079] During a walking cycle in a plane, the foot part 30 first strikes the ground with the heel, and the first contact of the heel or heel part of the foot part 30 is called the heel strike. Plantar flexion then takes place until the foot part 30 is completely flat on the ground, the longitudinal extension of the lower part 10 being usually behind a vertical line extending through the ankle axis 35. During walking in a plane, the center of gravity of the body is shifted forward, the lower part 20 swings forward, the ankle angle AA decreases and the load on the forefoot increases. The ground reaction force vector moves forward from the heel to the forefoot. At the end of the stance phase, the toes are released or the so-called toe-off, and then a swing phase follows, in which the foot part 30 is shifted to the rear of the center of gravity or the ipsilateral hip joint when walking in a plane with a reduced knee angle KA, so that it can be rotated forward after reaching the minimum knee angle KA, so that the heel contact can be achieved again here with the knee joint 1, which is usually maximally extended. The force introduction point PF is therefore moved from the heel to the forefoot during the stance phase and at the end of the stance phase, the foot part 30 is moved to the rear of the center of gravity or the ipsilateral hip joint with a reduced knee angle KA. Figure 1 It is schematically shown in FIG.

[0080] Walking on a flat surface is different from going uphill, going upstairs or other ways to overcome height differences. People's walking is mainly determined by the cooperative movement of the two legs. For example, in order to perform a step, the standing leg must take over the movement of the body's center of gravity and produce forward movement, while the swinging leg can achieve the positioning of the opposite foot in a way that maintains balance and can effectively transfer weight. The movement of both sides or legs is therefore functionally coupled and can be observed in different movements. The functional coupling of the movement is simulated by modeling, and the functional coupling of the components on the same side and the components on the opposite side can be used for this purpose, so as to determine the possible lack of information of each segment according to the characteristics or state of other segments. The method is set up to use the coupling of the individual segments of the cared for, on the same side, so as to implement or control the leg movement as usual and use it for intention recognition and for deriving the setpoint value change curve and target parameter. The present invention is set up to analyze the movement and the intended movement without a sensor device on the opposite side and generate control based on this evaluation. While in the case of bilateral care, the corresponding movement of the opposite side can be obtained by sensors located on the prosthesis, orthosis or exoskeleton or also by biological signals, such as muscle activity or the like, this possibility does not exist in unilateral care. Here, additional sensors must be arranged on the uncared contralateral side, whereby the entire system becomes significantly more complex. Therefore, it is provided that the missing values ​​are determined from the existing measured values ​​on the same side by means of a model, so as to save the need to equip the contralateral side with instruments. Even with sensors only on the same side, information about the movement of the contralateral leg in its standing phase, i.e. information about the translational knee or hip movement, can be obtained without the need to calculate these parameters of the contralateral leg in detail. The state of the cared, ipsilateral orthopedic device is detected by sensors in the orthopedic device (which receives the artificial knee joint), and the various parameters of the contralateral side are optionally derived from these sensor values. The motion parameters of the contralateral side are estimated from the measured data by means of a model. In the case of a mechanical model, boundary conditions and constraints can depend on the corresponding walking conditions. In order to control the actuator, not only the measured data, i.e. the sensor values, but also the estimated parameters are considered, and used to activate or deactivate the actuator.

[0081] The unilateral leg movement must be sufficiently determined technically, and the orthopedic device for crossing the knee is sufficient, for example, an inertial angle sensor 52 on the lower part, which detects the absolute angle and the horizontal acceleration, and an angle sensor 25, which is used to detect the knee angle KA between the upper part 10 and the lower part 20. In order to estimate the contralateral leg angle, for example, the ipsilateral leg movement is detected, the hip translation is calculated from this, and conclusions about the contralateral leg movement are drawn from this hip translation. In order to determine the translational movement of the hip, the translational movement of a point on the treated side, that is, a point on the orthopedic device, such as the movement of the knee axis, is taken into account. For example, the translational movement of the knee axis is determined in particular by double integration of the measured linear acceleration with suitable initial conditions. In the further course of the change, the kinematic chain up to the hip is tracked by absolute angles and relative angles. The initial conditions for the integration can be determined by a kinematic model, wherein the beginning of the integration is advantageously in the later standing phase. The rolling point of the foot part, also known as the center of rotation (COR), can be expressed as a function of load and orientation and included in the calculation. The segment lengths required for the calculation are measured and stored in the system, or assumed based on statistical values. Since, in particular, prosthetic care devices are often manufactured individually, the individual segment lengths are known, because these segment lengths must be detected in order to select components when assembling the prosthetic system. Alternatively, the segment lengths can be calculated with sufficient accuracy by means of a ruler from characteristic lengths (e.g., knee-to-ground dimensions) or amputation characteristics (e.g., amputation height) through an anthropometric model. Therefore, the trajectory of this point can be determined by double integration from the measured acceleration of a fixed point of the orthopedic system, such as the position of the swing axis. Then, through the kinematic chain, the hip trajectory is determined as a function of the relative degrees of freedom and the segment length. The translational movement of the hip is already a good measure for evaluating the intended movement, in particular, the horizontal component of the hip movement represents the share of the forward movement generated by the standing leg. Due to the cooperation of the swing leg movement and the stance leg movement, the reference of the swing leg movement on the same side to the hip translation enables the classification of the movement and the control of the prosthesis properties. The combination of the orientation of the upper part and the hip translation or the combination of the translation of the knee axis and the hip translation is particularly suitable for identifying which movement is being performed or intended, since these variables can be determined completely based on sensors in the orthopedic device.

[0082] In order to be able to estimate the contralateral leg angle, in which the leg angle between the hip joint and the landing point at the heel strike is measured relative to the direction of gravity, two assumptions are made, namely: the contralateral foot is in contact with the ground and the relative movement between the foot and the ground is therefore equal to 0; and at least one time point in the double support phase, when both feet or foot parts are on the ground, the contralateral inertial leg angle can be determined. This allows an assumption that the contralateral leg angle corresponds to the negative prosthetic leg angle. Starting from this initial condition, the change in the orientation of the contralateral leg angle can be calculated by trigonometric functions from the segment length and the relative translation of the hip. If the contralateral leg angle in its stance phase is related to the orientation of the upper part of the ipsilateral side in space in its swing phase, this relationship can indicate whether the user wants to go uphill, upstairs or intends to overcome a height difference ΔH in other ways when walking on the treated side. Typically, for such intended walking behavior, the angle of the upper part of the ipsilateral side is strongly tilted backwards in the middle of the swing phase, while the contralateral side is relatively less forward in the stance phase. In other words, the opposite side remains almost vertical, which means that there is little translational hip movement, while the upper member or thigh is strongly lifted and flexed.

[0083] If the artificial knee joint 1 stops in a flexed position at the end of the swing phase when walking uphill, the degree of this forward flexion can be determined in such a way that the angles of the ipsilateral and contralateral legs are in a harmonious relationship with each other when the treated side contacts the ground. In this case, in the orthopedic device, the flexion resistance and extension resistance in the form of the rated values ​​of the actuator 40 are set in the swing phase so that a harmonious relationship is set between the contralateral leg angle in the stance phase and the ipsilateral leg angle in the swing phase. The rated values ​​of the actuator 40 and thus the flexion resistance and extension resistance are set so that the maximum achievable knee angle KA max The adjustment is made as a function of the ascertained or estimated height difference ΔH of the ipsilateral foot part, wherein the height difference ΔH to the contralateral foot or foot part of the patient is plotted.

[0084] If an uphill climb, staircase or obstacle is detected while overcoming a height difference ΔH, the maximum extension of the lower part 20 relative to the upper part 10 is limited so that the maximum achievable knee angle KA max The lower part 20 stops at a specific angle of the lower part 20. Figure 2 This control is explained in FIG. 1 based on three states of the orthopedic device. If the lower part 20 is extended to the maximum extent unchanged relative to walking in a plane when the height difference ΔH is overcome, the knee angle KA that can be achieved is maxApproaching 180°, the foot part 30' is very far forward and touches the ground at a large plantar angle and the patient must rotate the hip around the ground over the entire leg chord length, which results in an unphysiological movement process. In contrast, according to the invention, at a certain maximum knee angle or at a certain orientation of the lower part, which can be detected, for example, by an inertial angle sensor 52, the extension of the lower part 20 is stopped before the maximum extension is reached, so that the foot part 30" is above the ledge or step at the end of the extension movement or at the end of the movement at the determined or estimated height difference ΔH. Subsequently, in a further movement variation curve, the thigh or upper part 10 descends, wherein the orientation of the lower part 20 preferably remains constant, i.e., the spatial position of the lower part 20 does not change, until the foot part 30"' touches the ground. This can be detected, for example, based on the occurrence of an axial force by an axial force sensor 54. If such an axial force FA is detected, it can be assumed that the swing phase is over and that in order to overcome the height difference ΔH not only the hip angle HA but also the knee angle KA increases, or at least does not decrease, so that due to the variable knee angle adjustment and forward flexion during walking, the effective leg chord length is shortened and less energy expenditure is required to overcome the height difference ΔH.

[0085] The greater the height difference ΔH to be overcome (which can be determined, for example, from a reduced forward tilt on the opposite side or from the maximum spatial orientation of the upper part 10 detected), the greater the maximum achievable knee angle KA max The reduction, that is to say, the forward flexion increases and the extension stop is displaced forward. The forward displacement of the extension stop can be performed by motor adjustment of the mechanical stop or by appropriate opening and closing of valves in a hydraulic or pneumatic control device inside the actuator 40.

[0086] If the vertical displacement of the hip is known or determined as an estimated value, the vertical displacement of the knee axis, i.e. the height difference against the direction of gravity G, can be calculated from the absolute angle of the upper part 10. The vertical displacement of the foot part can be calculated or estimated from the orientation of the upper part 10 in space in combination with the relative angle or knee angle KA which can be determined by the knee angle sensor 25. The knee angle sensor 25 makes it possible to determine the determined knee angle KAD and, in the presence of sensor data about the hip angle, in combination with the segment length, to calculate the height difference ΔH. Achievable knee angle KA max It is set during the swing phase of the ipsilateral leg and maintained until the predetermined spatial orientation of the lower part and / or the upper part is reached. Similarly, when monitoring the ankle angle AA, the achievable knee angle KA is maxThe setting can be maintained until a predetermined ankle angle AA is reached, which is determined, for example, as the angle set after the foot part 30 is lifted at the end of the stance phase when the foot part 30 is in the neutral position. If the foot part 30 touches the ground at this point, the ankle angle AA changes, which means that the maximum achievable knee angle KA can now be changed. max Alternatively, the position of the force introduction point can be determined by determining the force curve along the longitudinal extension of the foot part and the actuator 40 can be controlled accordingly depending on the position, so that further extension is blocked until a certain point in time and only then can the knee joint 1 be extended. Alternatively or additionally, a certain time period limiting the maximum extension can be determined by a time element.

[0087] The reaching of the minimum hip angle HA can be detected by monitoring the orientation of the upper part 10 in space. If the thigh or the upper part 10 is flexed to the maximum extent, the longitudinal extension of the upper part 10 is located at the maximum inclination relative to the direction of gravity G. If the upper part 10 is then swung downward about the hip joint and the longitudinal extension of the upper part 10 approaches the direction of gravity G, the minimum hip angle HA is reached and a reversal of movement has occurred. After the reversal of movement is detected, the maximum knee angle or, for example, the orientation of the lower part 20 in space can remain constant until the foot part 30 touches the ground, for example, by detecting the axial force FA or by a change in the ankle angle KA. The maximum achievable knee angle KA is set by varying the extension resistance. max , so that the foot part 30 touches the ground in the correct orientation when the leg is angled, and it is advantageous for the further movement process that after the reversal of the movement of the lower part 20 in the vertical direction, that is, when the lower part is lowered, the flexion resistance is kept at a high level in the swing phase on the same side, which is higher than the flexion resistance when walking on a flat surface, so that the body of the user of the orthotic device can be easily lifted when going uphill, climbing stairs, etc., and undesired flexion and bending of the knee joint 1 is avoided.

[0088] exist Figure 3 The corresponding angles and orientations in space and the corresponding reference quantities for illustrating the corresponding interrelationships are shown in FIG. The direction of the earth's gravitational force or the direction of gravity is indicated by the arrow g, and the orientation of the earth's gravitational force corresponds essentially to the vertical orientation. The orientation of the upper part 10 in space is determined by the angle The orientation of the lower part 20 in space is defined by the angle The hip angle HA is measured between the longitudinal orientation of the trunk and the longitudinal orientation of the upper part 10 on the front side in the g direction, and the knee angle KA is measured between the longitudinal extension of the upper part 10 and the longitudinal extension of the lower part 20 .

[0089] Figure 4is a diagram showing the movement process when going uphill. 0 Initially, the leg has an upper part 10, a lower part 20 and a prosthetic foot 30, wherein the prosthetic foot 30 has just touched the ground and is at the end of the stance phase. The unattended contralateral leg is completely on the ground and slightly flexed. At time t 1 , the leg being cared for is raised and in the maximum flexion position with the minimum knee angle KA. At time point t 2 , the foot part 30 moves in the direction of the ground and lowers, the lower part 20 is at the end of the extension movement in the swing phase and is braked, for example by activating a brake, increasing the damping rate or by adjusting an extension stop, by means of which the achievable knee angle is changed. 3 , the foot part 30 of the treated leg with the flexed knee joint 1 touches the ground, and the opposite, untreated leg relieves the load and moves forward. At the same time, a standing phase extension is performed for the treated leg, which at time t 4 The phase ends. The body center of gravity then moves forwards via the knee pivot axis 15 in the walking direction. With the knee joint extended, the lower part 20 is rotated forwards about the ground-side bearing point or rotation point and is arranged in the illustrated embodiment in the area of ​​the toe of the prosthetic foot 30. The movement cycle then begins again.

[0090] Figure 5 The corresponding movement sequence when overcoming a step is shown, wherein a further movement step is marked when overcoming the step, which is Figure 5 Marked as t 4 And in Figure 4 In the process, it is in the time segment t 3 With t 4 Between. Figure 5 Time point t 4 , the unattended contralateral leg is raised and is at a height just above the step to be overcome, and the contralateral knee has not yet moved in front of knee axis 15 of prosthetic knee joint 1 .

[0091] exist Figure 6The trajectory of the ankle joint A at the height of the ankle joint axis 35, the trajectory of the knee K at the height of the knee joint axis 15, and the trajectory of the trochanter Tr as the protruding point of the femur in the area of ​​the hip joint are drawn. Between the trajectories shown in solid lines, the orientation of the upper part 10 and the lower part 20 in the sagittal plane is shown. The trajectory and the orientation reflect walking in a plane, and the arrow direction illustrates the forward movement. At the beginning of the swing phase, when the toe is off the ground TO, the ankle joint A is slightly lifted compared to the standing state that has just been unloaded. After the toe is off the ground, it is led forward and slightly lifted by the knee joint K, thereby producing a whip effect, in which the ankle joint A is lifted and the greater trochanter remains almost unchanged at a level. During further forward movement, the knee joint K is further lifted and moves forward, and the ankle joint A surpasses the knee joint after about 40% of the walking cycle until the knee joint K is in a position of maximum extension, which is the case of heel contact or heel strike. This walking phase is marked with a solid line and the reference numeral IC of the initial contact. Due to the elasticity of the foot, the ankle axis sinks slightly and the leg rolls forward in the walking direction around the foot 30 or ankle axis 35, wherein the knee is slightly bent because of the flexion involved in the stance phase. At about 70% of the walking cycle, the greater trochanter exceeds the knee axis and the hip is brought in front of the knee and a forward movement is introduced. Each single dashed line represents one tenth of the walking cycle.

[0092] Figure 7 The trajectories of the ankle A, knee K and greater trochanter Tr are shown, for example, when walking uphill on a slope. It can be seen from the different trajectories that the same trajectory shape exists for the ankle joint A, but it is tilted upward. The orientation of the lower leg at the initial contact is different from the orientation of the lower leg when walking in a plane, and the orientation of the lower part relative to the upper part is also bent in the opposite direction to the state of maximum extension when walking in a plane. All trajectories end at a higher level than the level at which they start, which is given by the nature of the uphill slope.

[0093] According to FIG8 , the step height between the contralateral, untreated leg and the foot member 30 on the same side of the treated leg can be defined. For example, the distance H from the ground to a prominent point of the hip (eg, the greater trochanter) is 1 Determined as the height of the standing legs, spacing H 2 is the distance between the ground and the hip or the greater trochanter of the hip on the leading side (the side being treated in the example shown). Here, the height difference ΔH is given by H 1 With H 2 The definition of height difference ΔH applies accordingly for walking on a slope. Figure 8b The definition of the height difference ΔH* is shown, wherein the height difference between the height overcome on the same side and the height overcome on the same side, ie the height difference between lifting the treated leg until it touches the ground again, is measured, which corresponds to the height difference between toe-off and initial contact of the treated leg.

[0094] exist Figure 9 The following difference is shown in the figure, which means for the patient the difference between walking with the treated leg with a flexed knee joint and walking with the leg with an extended knee joint when a height difference is to be overcome. The left figure shows a walking with forward flexion and the right figure shows an extended walking, wherein the knee angle KA 2 Greater than the knee angle KA 1 The angle of forward flexion when stepping forward. Due to forward flexion, the step is tilted forward L 1 Less than the forward inclination of a step with extended legs. The body's center of mass COM must move forward in order to achieve a forward step. To do this, the moment arm L must be used as the distance between the center of mass COM and the vertical line of the landing point. *i , so that the body's center of gravity moves. *i The smaller the step, the less effort the patient must exert through the thigh musculature and hip extensors. 2 >, even when the user bends forward, the lever arm L *2 is also significantly larger, so that a significantly greater effort is required to overcome the height difference. In the case of a stretched step as in the right figure, the height difference ΔH must be compensated by a greater forward step inclination L compared to a forward flexed step. 2 Compensation is usually achieved by tilting the upper body forward, thereby trying to reduce the arm L between the landing point and the center of mass COM. * In addition, there is increased plantar flexion of the lagging stance leg, which is not visible in the figure.

[0095] exist Figure 10 The relationship between the knee angle KA and the height difference ΔH or step height is shown in FIG. The greater the step height or the height difference ΔH to be overcome, the smaller the knee angle KA, especially if the orientation of the lower leg should be the same during each step. Figure 11 This relationship for overcoming a step is shown in Figure 10 The situation when going uphill on a slope is shown in FIG.

[0096] Figure 12 The knee angle variation curves for different height differences ΔH are shown. When walking on flat ground with ΔH = 0, the knee angle changes when the toe leaves the ground TO 1Afterwards, the knee angle KA decreases to the minimum knee angle. The foot strap is then moved forward and the knee angle KA increases until it is almost fully extended at the heel strike or initial contact IC. The forward flexion is adjusted so that a flexion during the stance phase can be performed. The stance phase flexion increases at a time point of t / T=1.05 and then decreases to a maximum extension at t / T=1.4, which roughly corresponds to a rolling overturn. A forward flexion is then performed at the end of the stance phase to introduce the swing phase. As the height difference ΔH increases, it can be seen that the forward flexion during the heel strike or initial contact IC increases with the height difference ΔH; if necessary, the stance phase flexion can be reduced or suppressed with an increase in the height difference ΔH. The knee angle KA is plotted over dimensionless time by portions of the walking cycle, these divisions each corresponding to 10% of the walking cycle.

[0097] Figure 13 Shows thigh orientation in degrees The curve over a step cycle, which is divided into the corresponding components of the walking cycle, is plotted from the first initial contact or heel strike IC to the second initial contact IC2 or heel strike. The dashed line shows the thigh orientation for level walking The solid line is for uphill or climbing with ΔH>0. To identify climbing, it is possible to look at the thigh orientation The change curve is based on T 1 To T 3 The time period during which hip flexion increases (this is represented by a larger ) in a larger range of motion or greater swing, from T 2 To T 3 Between (in the form of ) or through the relationship between hip extension and hip flexion or through the relationship between flexion and range of motion The height difference ΔH is inferred. The calculation or estimation then results in a corresponding adjustment command from the control device for adapting the damping and / or the stop.

[0098] Figure 14 The thigh orientation for different height differences ΔH is shown Horizontal displacement relative to the hip or greater trochanter X H When ΔH 1 When walking on a flat surface, the range of motion is relatively small. As the height difference ΔH increases, the thigh orientation decreases with a shorter step length or a shorter horizontal displacement of the hip. From this relationship it can be inferred whether climbing or going uphill is taking place and whether and to what extent the extension stop or damping device should be adjusted. For example, when a threshold value for this relationship stored in the control unit is reached, the extension stop or damping device can be adjusted during the swing phase.

[0099] Figure 15 The diagram for estimating the step height or the height difference ΔH to be overcome, i.e. the thigh orientation, is shown. Horizontal displacement of the hip X H The rising slope K indicates the rising step height ΔH. The larger the step height ΔH, the higher the thigh orientation. Horizontal displacement X with the hip, such as the greater trochanter H The slope of the relationship is also greater.

[0100] exist Figure 16 The knee angle variation curve KA for one step cycle is shown in °, starting with toe-off TO, at 1 the heel strike HS or initial contact IC, and at 1.6 the second toe-off. In different walking phases, different goals are achieved by controlling the resistance or the stop. In area A, a controlled braking of the swing phase extension or an active extension of the knee joint to the corresponding desired forward flexion angle is performed. In phase B, control of the stance phase flexion occurs, for example flexion under high flexion resistance, in order to limit or prevent excessive stance phase flexion. In phase C, the stance phase extension is influenced, for example, by the extension rate, whereby the rolling and extension characteristics can be influenced. In phase D, the stance phase extension is braked in order to avoid a hard stop into the extension stop when the roll-off has occurred and the maximum knee angle has been reached.

[0101] An application embodiment of an energy accumulator (which can be integrated in an active or semi-active actuator) provides that the energy accumulator is used in the selected walking phase. Kinetic energy can be stored in particular during the stance phase extension, that is, during phases C and D, and in these phases, in particular during the braking period in the stance phase extension, which corresponds to phase D. In order to support the swing phase flexion, in particular directly after the introduction of the swing phase, the stored energy is output again. It is also possible that kinetic energy is stored during the stance phase extension in phase D so that it is output again during the swing phase extension in phase A, there, in particular in the second half of the stance phase extension. This supports the correct positioning of the foot. In principle, kinetic energy can also be stored in other motion phases and output again in other motion phases. It is not necessary to directly output all the stored kinetic energy again, and it is also possible to sum the stored energy in different or identical motion phases, for example, on multiple motion phases of a step or across multiple steps.

[0102] Figure 17Shows the angle of the calf Different control profiles for extension in the stance phase. The knee extension can be controlled so that in profile A the lower leg or lower part 10 maintains an approximately constant orientation during the knee extension movement. Alternatively, according to profile B, a certain forward rotation of the lower part 20 and the lower leg can be allowed, and the forward rotation speed is determined as a defined measure. Profile C sets a certain degree of backward rotation or a backward rotation speed. All three control variants can, if necessary, depend on the walking speed, step height, step length and the degree of knee flexion. Calf angle It is also plotted over the phase of a walking cycle from initial contact IC to the beginning of the swing phase when the toe leaves the ground TO.

[0103] Figure 18 Two different knee angle curves KA are also shown over the phases of the walking cycle, wherein here the phase after the initial contact IC is performed with a relatively rigid forward flexion of 20 degrees. The curve according to the solid curve A suppresses the flexion during the stance phase, while the curve according to the dashed curve B allows a further flexion during the stance phase of 30 degrees, but the degree of flexion during the stance phase is controlled and the maximum knee flexion is limited. The two variants can be used depending on the walking speed, step height, step length and the curve of the force application point in the foot part.

[0104] Figure 19 The possible resistance curves in passive control and in the case of suppressed flexion during the stance phase are shown according to three graphs. The upper graph shows the knee angle curve KA, the middle graph shows the flexion resistance R flex , the lower graph shows the extension resistance R during a walking cycle from toe-off 1 to toe-off 2 ext , where 1.0 is the initial contact IC or heel strike. All three curves are plotted over dimensionless time as a fraction of the walking cycle. Before initial contact IC, the flexion resistance R flex The flexion resistance R increases to a maximum value, thereby exerting a maximum flexion resistance at the initial contact IC of the foot component. The increase in phase A occurs during the swing phase extension, and the knee joint is locked at the initial contact IC. After the initial contact IC, in phase B, for example, when the stance phase extension occurs, the flexion resistance R flexIt is reduced again to the stance phase extension so that a rapid drop in the extension resistance can then be achieved at the end of the stance phase to introduce the swing phase. During the swing phase extension, the extension resistance is increased in phase C before the initial contact IC in order to stop the knee joint at a defined knee angle KA. It is not necessary to completely lock the extension movement. A sufficient reduction in the extension movement can be achieved by gradually increasing the resistance in order to adequately stop the joint. Subsequently, the extension resistance is reduced as necessary depending on the walking speed, step height, step length, existing knee flexion and the course of the ground reaction force vector. Subsequently, during the stance phase extension movement, the extension resistance R is increased in a controlled manner. ext , for example by adjusting to the desired extension of the knee joint or according to the calf angle Finally, the stance phase extension is maintained by further extension in phase F in order to avoid a hard stop in extension or when the desired knee angle KA is reached.

[0105] Figure 20 Basically equivalent to Figure 19 , however, other curves of the knee angle KA and the corresponding resistance over a walking cycle are shown. Figure 19 The change curve of the buckling resistance R flex It is not increased to a maximum value before the initial contact IC, but is decreased to a lower value after the maximum value for braking in flexion during the swing phase until the flexion resistance R is increased in phase B after the initial contact IC. flex , to achieve controlled stance phase flexion. The rise in phase B is used to control the rate of flexion or the degree of stance phase flexion. The flexion resistance R flex The magnitude of the increase depends on the desired maximum flexion angle. Subsequently, in phase C, the flexion resistance is reduced again, similar to Figure 19 Phase B. Stretch resistance R ext As in Figure 19 is adjusted as described in the variation curve.

[0106] Figure 21 The dotted line shows the calf angle when the height difference ΔH is equal to 0 when walking on a flat surface. Angle relative to thigh Here, the characteristic points of walking are also represented by toe-off TO and initial contact IC. The solid line represents the calf angle when the height difference ΔH is greater than 0 when going uphill or climbing an obstacle. Angle with thigh The divisions are made corresponding to 10% of a walking cycle respectively. The different curve trends make it possible to estimate how large the height difference ΔH that is overcome or to be overcome is. In particular, the curve trend after 80 percent of the walking cycle, i.e. after the two lines after toe-off TO or at 0.8, shows that walking on a flat surface with ΔH equal to 0 rises more steeply than walking uphill or climbing with a height difference ΔH greater than 0. Different variation curves can be determined or stored for different height differences ΔH, which can be used by the control device in order to be able to make corresponding adjustments of the stops and resistances to match the corresponding walking conditions.

[0107] Figure 22 The dotted line shows the knee angle KA relative to the thigh angle when the height difference ΔH is equal to 0 walking in a plane. The relationship between the knee angle KA and the thigh angle is shown in a solid line when the height difference ΔH is greater than 0 when climbing an obstacle or going uphill. 0.6 in a step cycle and at toe-off in the region of 0.8 in a walking cycle result in a significant difference in the curve curve, which is then used to estimate the height difference ΔH according to the comparison algorithm and to enable the control device to perform a corresponding adjustment of the resistance or stop.

[0108] exist Figure 23 The leg chords of the treated leg on the same side and the untreated leg on the opposite side are defined in FIG. The leg chords pass through the hip rotation point and form a line to the ankle joint. Figure 23 It can be seen that the length of the leg chord and the orientation of the leg chord The height difference ΔH to be overcome can be estimated and predicted or determined by the change curve of the change in the length and / or orientation of the leg string. The corresponding control instructions are then derived from this. The corresponding orientation of the leg string on the same side is plotted in each case relative to the direction of gravity G. and the corresponding orientation of the contralateral leg chord

Claims

1. A method for controlling an artificial knee joint (1), the artificial knee joint having: an upper member (10) with a front side (11) and a rear side (12); a lower member (20) pivotally supported on the upper member (10) about a knee axis (15), the lower member having a front side (21) and a rear side (22); a foot member (30) arranged on the lower member (20); at least one sensor (25, 51, 52, 53, 54); a control device (60) connected to the at least one sensor (25, 51, 52, 53, 54); and an actuator (40), the actuator being coupled to the control device (60) and the maximum achievable knee angle (KAmax) between the rear side (12) of the upper member (10) and the rear side (22) of the lower member (20) during the swing phase being adjustable via the actuator by the control device (60). Characterized in that from the sensor data of the at least one sensor (25, 51, 52, 53, 54), the height difference (ΔH) between the foot member (30) and the opposite foot (33) or foot member of the patient during the standing phase of the patient when walking is inferred, or the height difference from the immediately preceding standing phase of the foot member (30), and the maximum achievable knee angle (KAmax) during the swing phase is adjusted, and when the height difference (ΔH) increases against the direction of gravity (G), the maximum achievable knee angle (KAmax) decreases.

2. The method according to claim 1, Characterized in that the height difference (ΔH) is calculated or estimated from the trajectories of the torso, pelvis, hip and / or the knee axis of the leg to be cared for.

3. The method according to claim 2, Characterized in that the height difference (ΔH) is calculated or estimated by the vertical displacement of the hip joint of the leg to be cared for, the vertical displacement of the knee axis (15) and / or the vertical displacement of the foot member (30).

4. The method according to claim 2 or 3, Characterized in that the height difference (ΔH) is obtained by the hip angle (HA) of the leg to be cared for or the orientation of the upper member (10) in space and / or the time curve of the orientation of the upper member in space.

5. The method according to claim 2 or 3, Characterized in that the height difference (ΔH) is obtained by the time curve of the knee angle of the leg to be cared for.

6. The method according to claim 4, Characterized in that the height difference (ΔH) is calculated or estimated from the relationship between the horizontal movement of the torso, pelvis, hip or the knee axis (15) of the leg to be cared for and the hip angle (HA) or the orientation of the upper member (10) in space.

7. The method according to claim 4, Characterized in that the height difference (ΔH) is calculated from the obtained knee angle (KAD) and the obtained hip angle (HA).

8. The method according to any one of claims 1 to 3, Characterized in that The maximum achievable knee angle (KAmax) is set by means of an adjustable mechanical or hydraulic extension stop (45) or a change in the movement resistance against knee extension.

9. The method according to any one of claims 1 to 3, characterized in that the orientation of the lower part (20) in space is used as a characteristic parameter for the maximum achievable knee angle (KAmax).

10. The method according to any one of claims 1 to 3, characterized in that the height difference (ΔH) is determined or estimated from the knee angle (KAD) measured by means of the knee angle sensor (25) on the artificial knee joint (1) and / or from the spatial orientation of the upper part (10) and / or the lower part (20) measured by means of the spatial orientation sensors (51, 52).

11. The method according to any one of claims 1 to 3, characterized in that the maximum achievable knee angle (KAmax) is set in the swing phase and maintained until a predetermined spatial orientation is reached and / or the lower part (20) and / or the upper part (10) are moved until the ankle angle (AA) is reached and / or the force introduction point (PF) in the foot part (30) is reached, and / or is maintained for a predetermined period of time.

12. The method according to any one of claims 1 to 3, characterized in that after the minimum hip angle (HA) is reached and the movement is reversed, the orientation of the lower part (20) in space remains constant until initial contact is detected, an axial force (FA) acting on the lower part (20) and / or a change in the ankle angle (AA).

13. The method according to any one of claims 1 to 3, characterized in that uphill, upstairs or other overcoming of height differences during walking is detected by means of the time curve of the orientation of the upper part and / or by the relationship between the orientation of the upper part and the translational horizontal movement of the knee axis (15), and the maximum achievable knee angle (KAmax) is adjusted based on the curve and / or the relationship.

14. The method according to any one of claims 1 to 3, characterized in that after the movement direction of the lower part (20) is reversed, the flexion resistance in the swing phase is set to a higher level than when walking on a flat surface.

15. The method according to any one of claims 1 to 3, characterized in that when an uphill, upstairs or other overcoming of a height difference (ΔH) during walking is recognized, the maximum achievable knee angle (KAmax) is reduced by 10° to 25°.

16. The method according to any one of claims 1 to 3, characterized in that the movement resistance against the extension movement of the knee joint is continuously reduced in the swing phase.

17. The method according to any one of claims 1 to 3, characterized in that the height difference (ΔH) is used as a characteristic parameter for the maximum achievable knee angle (KAmax), and the actuator (40) is activated or deactivated based on the characteristic parameter.

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