Abstract:
A simulator for driving a prosthetic element includes a prosthetic drive mechanism that drive the prosthetic element during an accelerated wear test of the prosthetic element. A simulation input represents the action of the simulator and a sensor mechanism is used to measure the force and torque applied to the prosthetic element. Position and orientation control sensors are further used to measure displacement of the prosthetic element. A closed loop feedback control system, responsive to the sensors, is used to determine a drive signal for the drive mechanism. The control system advantageously adds a computational model that incorporates mechanical representations of ligament fibers. The computational model is a non-human approximation to situations that would be encountered by the prosthesis within the human body and includes dimensional geometry of insertion sites and mechanical properties of ligament fibers. The computational model is responsive to the position and angular displacement sensors to determine constraint forces and torques of ligaments that mitigate action of the control system. The action of the control system may further be mitigated by the measured force and torque.
Abstract:
A method for calibrating a force platform includes, providing a force platform and applying an nXm grid on a top surface of the force platform via a computing device. Next, applying p known loads on each of the nXm grid points of the top surface along a Z-axis being perpendicular to the X and Y axes and along the X and Y axes. Next, taking multipoint measurements at each grid point and for each applied known load along the X,Y and Z axes and generating six measured output signals, exact position coordinates and applied known load magnitude for each grid point. Next, assembling an array of nXmXp of six equations with six unknown for each grid point and applied known load and then solving the assembled equations and deriving a position and load specific calibration matrix for each grid point.
Abstract:
A simulator for driving a prosthetic element includes a prosthetic drive mechanism that drive the prosthetic element during an accelerated wear test of the prosthetic element. A simulation input represents the action of the simulator and a sensor mechanism is used to measure the force and torque applied to the prosthetic element. Position and orientation control sensors are further used to measure displacement of the prosthetic element. A closed loop feedback control system, responsive to the sensors, is used to determine a drive signal for the drive mechanism. The control system advantageously adds a computational model that incorporates mechanical representations of ligament fibers. The computational model is a non-human approximation to situations that would be encountered by the prosthesis within the human body and includes dimensional geometry of insertion sites and mechanical properties of ligament fibers. The computational model is responsive to the position and angular displacement sensors to determine constraint forces and torques of ligaments that mitigate action of the control system. The action of the control system may further be mitigated by the measured force and torque.
Abstract:
An apparatus and method for a multi-axis wheel transducer are disclosed. The apparatus of the invention comprises a wheel transducer for measuring the loads and moments acting on a vehicle wheel. Tubular load cells positioned in a radial fashion around the perimeter of the transducer hub join the rim and hub. Loads and moments acting on the rim of the wheel are transferred through the spoke-like load cells to the hub of the wheel. Sensors strategically positioned around the circumference of the tubular load cell monitor the intensity of the loads and moments. To detect angular position of the wheel, a light source generates a cone of polarized light to flood the wheel of the vehicle and detector-polarizing filter pairs detect an angle of the polarization relative to the wheel to determine its angular position. The transducer hub computer processes the sensor data and transfers the information via infrared signal to a computer located in the fender of the vehicle.
Abstract:
A joint motion simulator to simulate biomechanical motion includes a mount to which a prosthetic device is mounted, actuators coupled to the mount to drive the mount, and a programmable controller to drive the actuators to translate the mount and to rotate the mount with a center of rotation controllable independent of translation. The simulator can include a linear actuator to translate the mount in a linear direction substantially parallel to the axis of rotation. The linear actuator can include a piston within a sleeve, the piston being coupled to the mount and being hydraulically driven to translate the mount, and the actuators can be coupled to the sleeve. The controller may be programmed to vary the center of rotation with linear translation and rotation of the mount. Sensors may be included that measure displacement of the actuators. The controller may drive the actuators based on the measured displacement.
Abstract:
A joint motion simulator to simulate biomechanical motion includes a mount to which a prosthetic device is mounted, actuators coupled to the mount to drive the mount, and a programmable controller to drive the actuators to translate the mount and to rotate the mount with a center of rotation controllable independent of translation. The simulator can include a linear actuator to translate the mount in a linear direction substantially parallel to the axis of rotation. The linear actuator can include a piston within a sleeve, the piston being coupled to the mount and being hydraulically driven to translate the mount, and the actuators can be coupled to the sleeve. The controller may be programmed to vary the center of rotation with linear translation and rotation of the mount. Sensors may be included that measure displacement of the actuators. The controller may drive the actuators based on the measured displacement.