The “Rutgers Ankle” is a Stewart platform-type haptic interface designed for use in rehabilitation The system supplies six-DOF resistive forces in response to virtual reality-based exercises running on a host PC The Stewart platform uses double-acting pneumatic cylinders, linear potentiometers as position sensors, and a six-DOF force sensor The Rutgers Ankle controller contains an embedded Pentium board, pneumatic solenoid valves, valve controllers, and associated signal conditioning electronics Communication with the host PC is over a standard RS232 line The platform movement and output forces are transparently recorded by the host PC in a database This database can be accessed remotely over the Internet Thus, the Rutgers Ankle Orthopedic Rehabilitation Interface will allow patients to exercise at home while being monitored remotely by therapists A prototype was constructed, and proof-of-concept trials were conducted at the University of Medicine and Dentistry of New Jersey The results indicate that the system works well as a diagnostic tool The subjective evaluation by patients was very positive Further medical trials are needed before the system clinical efficacy in rehabilitation can be established

A Stewart Platform-Based System for Ankle Telerehabilitation

On the dynamic model and kinematic analysis of a class of Stewart platforms

The “Rutgers Ankle” is a Stewart platform-type haptic interface designed for use in rehabilitation. The system supplies six-degree-of-freedom (DOF) resistive forces on the patient's foot, in response to virtual reality-based exercises. The Rutgers Ankle controller contains an embedded Pentium board, pneumatic solenoid valves, valve controllers, and associated signal conditioning electronics. The rehabilitation exercise used in our case study consists of piloting a virtual airplane through loops. The exercise difficulty can be selected based on the number and placement of loops, the airplane speed in the virtual environment, and the degree of resistance provided by the haptic interface. Exercise data is stored transparently, in real time, in an Oracle database. These data consist of ankle position, forces, and mechanical work during an exercise, and over subsequent rehabilitation sessions. The number of loops completed and the time it took to do that are also stored online. A case study is presented of a patient nine months post-stroke using this system. Results showed that, over six rehabilitation sessions, the patient improved on clinical measures of strength and endurance, which corresponded well with torque and power output increases measured by the Rutgers Ankle. There were also substantial improvements in task accuracy and coordination during the simulation and the patient's walking and stair-climbing ability.

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Post-Stroke Rehabilitation with the Rutgers Ankle System: A Case Study

A joint-space adaptive control scheme for controlling noncompliant motion of a Stewart platform-based manipulator (SPBM) was implemented in the Hardware Real-Time Emulator at Goddard Space Flight Center. The six-degrees of freedom SPBM uses two platforms and six linear actuators driven by dc motors. The adaptive control scheme is based on proportional-derivative controllers whose gains are adjusted by an adaptation law based on model reference adaptive control and Liapunov direct method. It is concluded that the adaptive control scheme provides superior tracking capability as compared to fixed-gain controllers.

Adaptive control of a stewart platform‐based manipulator

This paper introduces a new method of providing motion cues to a moving base six-degree-of-freedom flight simulator utilizing nonlinear filters. Coordinated adaptive filters, used to coordinate translational and rotational motion, are derived based on the method of continuous steepest descent, and the basic concept of the digital controllers used for the uncoordinated heave and yaw cues is also presented. The coordinated adaptive washout method is illustrated by an application in a six-degree-of-freedom fixed-base environment.

Coordinated Adaptive Washout for Motion Simulators

A set of equations which transform position and angular orientation of the centroid of the payload platform of a six-degree-of-freedom motion simulator into extensions of the simulator's actuators has been derived and is based on a geometrical representation of the system. An iterative scheme, Newton-Raphson's method, has been successfully used in a real time environment in the calculation of the position and angular orientation of the centroid of the payload platform when the magnitude of the actuator extensions is known. Sufficient accuracy is obtained by using only one Newton-Raphson iteration per integration step of the real time environment.

https://ntrs.nasa.gov/api/citations/19730003455/downloads/19730003455.pdf

J. E. Dieudonne

Papers

An actuator extension transformation for a motion simulator and an inverse transformation applying Newton-Raphson's method