Please Note: The technology listed below is not available to the public at this time. This technology is in the early stage of research and requires further development before it is ready for the marketplace. The VA is currently in the process of identifying potential companies who may be interested in licensing and/or further developing the technology through Cooperative Research and Development Agreements (CRADA). Through cooperative research initiatives such as these, it is our hope and goal that commercial products will be fully developed and made available to benefit veterans and others.  

VA TECHNOLOGY OPPORTUNITY BRIEF

Variable Compliance Joystick with Compensation Algorithms

(02-023)

OPPORTUNITY:
The Department of Veterans Affairs (VA) is seeking a commercial partner to further develop this technology through a Cooperative Research & Development Agreement (CRADA) to expedite bringing it to market.

BACKGROUND: Patients with tremors or other involuntary motion disorders often cannot operate typical joystick controllers for wheelchairs or other applications. The technology enables some of these patients to utilize joystick control by compensating for the unwanted motion.

TECHNOLOGY OVERVIEW: The technology is an improved version of an isometric joystick. The joystick contains an internal microcontroller with memory that uses compensatory algorithms to modify signals generated by the joystick forces on each strain gauge. The algorithms are used to filter and limit the unwanted motion. The joystick can be used in full isometric mode or in a variable compliance mode. The variable compliance mode provides tactile feedback that gives the operator an indication of joystick position, freeing the use of vision for maneuvering the wheelchair. A wheelchair - driving simulator is used to customize software and mechanical parameters of the joystick to determine the optimal driving configuration. The simulator uses a computer generated rendition of a wheelchair course displayed on a large-screen computer monitor and a stationary wheelchair placed before the monitor. The wheelchair is fitted with a joystick, but instead of the joystick controlling motion of the wheelchair, the joystick controls the motion of a wheelchair icon on the monitor. The simulator scores each driving task, enabling the therapist to determine the optimal mechanical and software configuration for the patient.

TECHNICAL MERIT: The novelty of the technology is the combination of an improved joystick, a method of performing software and hardware customization of the joystick for wheelchair control, and a wheelchair simulator to facilitate the joystick optimization. The result is a customized joystick that can be closely matched to the patient by use of the simulator to optimize software and hardware characteristics of the joystick. The advantages of each component are listed below:

•   The joystick is mechanically configurable:
•    Both variable compliance and full isometric modes are available to best adapt to the user.
•    Damping may be incorporated to reduce the effects of unwanted motion.
•   The joystick incorporates compensation algorithms with the following features:
•   A dead zone - an empirically determined elliptical area in which the joystick ignores input.
•   Filtering to reduce effects of tremors and other spurious motions.
•   Axes of motion that need not be orthogonal, thus enabling a user to find the best joystick motions for forward/reverse, left/right directions.
•   Axes of motion that need not be orthogonal, thus enabling a user to find the best joystick motions for forward/reverse, left/right directions.
•   The wheelchair simulator facilitates matching of joystick mechanical and software parameters to individual users.

PATENT STATUS: A provisional patent application, 60/406,682, for this invention was filed on August 29, 2002.
An international patent application was filed on Aug. 29, 2003 (PCT/US03/27163)
Federal Register: March 1, 2004 (Vol. 69, No. 40) p. 9678
CIP application filed on Feb 25, 2005 (11/068,655)

FOR MORE INFORMATION CONTACT:
Saleem Sheredos
Program Manager
Technology Transfer Program
Veterans Affairs
Office of Research & Development (12TT)
5th Floor
103 South Gay Street
Baltimore, MD 21202
202-380-5080
Fax 410.962.2141
e-mail: saleem.sheredos@va.gov