Forma 0503775

A leg prosthesis having an artificial knee joint with swing phase control and recoil break comprises a damping member acting upon the knee joint, detectors for detecting force, knee angle and acceleration and a control unit for controlling the dampening degree of the damping member on the basis of the detected values. The damping characteristics of the damping member are varied in dependence on control signals produced by the control unit on the basis of a viscosity change of the magneto-rheological liquid. The invention relates to a leg prosthesis comprising an artificial knee joint having swing phase control and recoil brake wherein a control member provided at the knee joint controls the knee joint depending on control signals based on a viscosity change of a magneto-rheological liquid. When walking with a prosthesis the thigh member is moved forward by the residual limb.

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The leg member may, owing to its mass inertia, bend back very far if the damping is not properly adjusted. The wearer of the prosthesis then has to wait until the prosthesis moves again in forward direction before putting the foot on the ground. This results in an unharmonious walking appearance, an unfavourable time characteristic and therefore poor wearing properties. It is known to provide leg prostheses comprising an artificial knee joint with a damping member formed as a pneumatic or hydraulic cylinder for swing phase control and as a so-called recoil brake. The leg prosthesis is adapted to the wearer by means of a stationary walking pattern analysis system.

The wearer of the prosthesis must do a test run, for example on a walking band, and the walking pattern is then subjectively evaluated by an orthopedic technician. Taking also the subjective sensations of the wearer of the prosthesis into account, the various components of the prosthesis are then adapted and adjusted.

The result of this adjustment is often inaccurate because it is based on subjective criteria. Further, later changes such as weight changes, temperature changes or changes of the ground conditions are not taken into consideration.

Moreover, the known damping members for artificial knee joints are disadvantageous in that they are unable to react in a sufficiently fast manner to an abrupt change of the walking dynamics. It is the object of the invention to provide a leg prosthesis comprising an artificial knee joint with a swing phase control and a recoil brake, the leg prosthesis ensuring an always optimum operation which is adapted to the wearer as well as fast reaction to abrupt changes of the walking dynamics.

This object is achieved by a control based on a viscosity change of a magneto-rheological liquid and an automatic control producing control signals on the basis of detected values to automatically regulate the knee joint functions during the operation of the prothesis. Further features and advantages of the invention will be apparent from the description of an embodiment with reference to the FIGURE. The FIGURE shows, in schematic representation, a leg prosthesis comprising an artificial knee joint with a swing phase control and a recoil brake and a corresponding control or regulation, respectively. In conventional manner the prosthesis comprises a thigh member 1 and a leg member 2 and a knee joint 3 joining both members. The leg member 2 comprises a shin part 4 having a lower leg tube 9 and a foot member 5 attached thereto. The foot member 5 comprises a leaf spring which is not shown in the FIGURE for allowing resilient steps.

Vikings conquest serial key. The thigh member 1 is formed for connection with the residual limb. The knee joint 3 comprises a damping member in form of a hydraulic piston-cylinder device 6. The piston 7 of the piston-cylinder device 6 is connected to the shin part 4 and the piston rod 8 of the piston-cylinder device 6 is connected with the knee joint 3. The cylinder of the piston-cylinder device is filled with a magneto-rheological liquid (MR fluid) having the characteristics of changing its viscosity within about 3 to 5 milliseconds when subjected to a magnetic field.

The magneto-rheological liquid consists of a suspension of magnetizable particles having a size on the order of micrometers in oil. Under normal circumstances the consistence of a magneto-rheological liquid is similar to that of engine oil. When subjected to a magnetic field the viscosity abruptly increases whereby the change is proportional to the intensity of the magnetic field. Elite volare mag lite indoor trainer manual. The piston 8 or the cylinder 7 of the piston-cylinder device 6 further comprises a solenoid which can be controlled by external signals and generates the magnetic field affecting the magneto-rheological liquid.