System and method for joint motion simulation

A control system for use in driving a prosthetic element, the control system comprising:

• a database storing representations of plural individual ligaments, wherein each ligament is represented by at least two fibers, the mechanical properties of each fiber are independently defined and adjustable, each end of each fiber is attached to at least one insertion site during simulated joint motion, said sites independently defined and adjustable in a three-dimensional space, the system configured to define insertion sites not limited to anatomical insertion sites geometry;
• and
• a processor executing a computational model that incorporates the representations of the ligament fibers and responds to displacement sensors that measure displacement of the prosthetic element, to determine length of each ligament fiber, based on position of the fiber's insertion sites, and, using the mechanical properties and length of each fiber, determine constraint forces with respect to each ligament fiber,
• the control system combining the determined constraint forces and a measured force applied to the prosthetic element with a simulation input to drive a prosthetic drive mechanism that drives the prosthetic element.

A simulator for driving a prosthetic element, comprising:

• a prosthetic drive mechanism configured to drive the prosthetic element during an accelerated wear test of the prosthetic element;
• a sensor mechanism that measures force applied to the prosthetic element;
• position and angular displacement sensors that measure displacement of the prosthetic element;
• a simulation input representing action of the simulator;
• and
• a closed loop feedback control system responsive to the sensors to determine a drive signal for the drive mechanism, the control system including a computational model that incorporates mechanical representations of plural individual ligaments, wherein each ligament is represented by at least two fibers, the mechanical properties of each fiber are independently defined and adjustable, each end of each fiber is attached to at least one insertion site during simulated joint motion, said sites independently defined and adjustable in a three-dimensional space, the system configured to define insertion sites not limited to anatomical insertion sites geometry;
• the model responding to the position and angular displacement sensors to determine length of each ligament fiber, based on position of the fiber's insertion sites, and, using the mechanical properties and length of each fiber, determine constraint forces with respect to each ligament fiber, the control system combining the determined constraint forces and measured force with the simulation input to determine the drive signal.

A method of driving a prosthetic element in a simulator comprising:

• providing a computational model that incorporates representations of plural individual ligaments, wherein each ligament is represented by at least two fibers, the mechanical properties of each fiber are independently defined and adjustable, each end of each fiber is attached to at least one insertion site during simulated joint motion, said sites independently defined and adjustable in a three-dimensional space;
• applying a simulation input to a control system that drives the prosthetic element, the system configured to define insertion sites not limited to anatomical insertion sites geometry;
• sensing force applied to the prosthetic element;
• sensing displacement of the prosthetic element;
• in the computational model, responding to the sensed displacement to determine length of each ligament fiber, based on position of the fiber's insertion sites, and, using the mechanical properties and length of each ligament fiber, determine constraint forces with respect to each fiber;
• combining the simulation input with the determined constraint forces and the measured force in driving the prosthetic element.