US 5,062,857 AGranted

Myoelectrically controlled knee joint locking device

AssigneeAdvanced Prosthestetics Development Corporation

InventorsWIlliam A. Berringer, Edward J. Sulima, Jr.

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Abstract

A damped knee joint may be locked myoelectrically at any angle of flexing. A special hydraulic cylinder is pivoted above the knee center at one end and in the shank at the other end. This attachment strategy allows 110 degrees of knee flexion, permitting the normal range of sitting and standing positions. The cylinder assembly incorporates a closed loop, sealed hydraulic system and electro-mechanical valving to control piston position. The closed loop hydraulic system also prevents fluid leakage and contamination. Valving is accomplished by a microelectrically operated barrel or gate valve located in a hydraulic system. The use of a barrel or gate valve allows the microelectrically operated plunger to be physically isolated from the working fluid and to be operated reliably at the highest working pressure of the systems.

A myoelectrically controlled knee joint locking device, said device comprising:

an upper artificial limb,
a lower artificial limb pivotably mounted on said upper artificial limb for free-swinging extension and retraction of said lower artificial limb with respect to said upper artificial limb,
a hydraulic piston cylinder assembly, a piston rod of said assembly being pivotably mounted on said upper artificial limb, a cylinder of said assembly being pivotably mounted on said lower artificial limb,
a piston mounted on said piston rod being slidably mounted in said cylinder,
hydraulic fluid being in sealed communication with opposite sides of said piston for movement of said piston in two opposite directions and transfer of said fluid to opposite sides of said piston,
retraction adjustment means for regulating flow of said hydraulic fluid and therefore the speed of retraction of said lower artificial limb when said piston is moved in one of the two opposite directions by movement of said lower artificial limb with respect to said upper artificial limb,
extension adjustment means for regulating flow of said hydraulic fluid therefore the speed of extension of said lower artificial limb when said piston is moved in the other of the two opposite directions by movement of said lower artificial limb with respect to said upper artificial limb,
a single sensing means mounted on a single muscle of the user for generating a single signal in response to a detected myoelectric potential generated voluntarily or involuntarily by the muscle of the user in response to a desired instantaneous locking of said hydraulic piston cylinder assembly against retraction of said lower artificial limb, and
control means responsive to said signal for controlling said assembly to permit only extension of said artificial limb with respect to said upper artificial limb and to instantaneously lock said assembly against retraction of said lower artificial limb at any point along a path of travel of said piston rod.

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Abstract

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