A five-wheel wheelchair with an active-caster drive system.

Area of Science:

• Robotics and Mechanical Engineering
• Assistive Technology
• Biomechanics

Background:

• Manual wheelchairs limit user mobility and require significant physical effort.
• Existing electric wheelchairs often have complex control systems and limited maneuverability.
• The non-holonomic constraint of standard drive wheels restricts independent control of motion.

Purpose of the Study:

• To develop a novel active-caster drive mechanism for motorizing manual wheelchairs.
• To achieve independent 2-degree-of-freedom (DOF) control of wheelchair motion without constraints.
• To enable dual drive modes (front and rear) for enhanced maneuverability and adaptability.

Main Methods:

• Designed an active-caster mechanism with two independently controlled electric motors for wheel and steering axes.
• Developed kinematic models for the wheelchair and the active-caster system.
• Implemented a 2-DOF joystick control method and a linear actuator for vertical drive wheel actuation.
• Built and tested a prototype five-wheel wheelchair system.

Main Results:

• The active-caster system successfully achieved independent 2-DOF wheelchair control, enabling translation, rotation, and compound motions.
• The prototype demonstrated seamless switching between front and rear drive modes.
• The system overcame non-holonomic constraints, offering greater control flexibility than standard electric wheelchairs.
• Experimental validation confirmed the feasibility of the proposed mechanism and control strategy.

Conclusions:

• The novel active-caster drive system significantly enhances wheelchair maneuverability and user control.
• The dual drive mode capability offers adaptable mobility solutions for diverse environments.
• This technology represents a promising advancement in assistive device design for improved user independence.