Over the last two decades, the number of people who have difficulty walking and need wheelchairs has been found to be increasing due to an... Show moreOver the last two decades, the number of people who have difficulty walking and need wheelchairs has been found to be increasing due to an aging population caused by a low birth rate and advances in medical treatment. Based on a recent survey, a power assisted wheelchair is the latest one in the commercial wheelcair market. The power assisted wheelchair offers users an opportunity for physical activity, but it is often too expensive for customers. This has led to the design of more advanced and economical power assisted drivetrain systems for wheelchairs. In this thesis, a novel controller has been designed. Instead of using a torque sensor for measuring and amplifying human force, the proposed controller uses two infrared sensors to trigger two motors. Using this information in addition to the information from a motion sensor that detects the road angle variation, appropriate torque command is generated. The drivetrain requires the embedded controller has a strong I/O control function, but also high speed signal processing ability for realizing real time control. Therefore, a DSP (Digital Signal Processor) which integrates flexbile multiple PWM signal generator to drive two motors, two Hall sensors for motor position and speed feedback is considered as one of the strongest controllers for power assisted drivetrain implementation. This thesis has two main contributions: a) it presents a novel power assisted motor control strategy, including six-step motor control, Environmental Adaptive control and Push-Go control method; and b) it develops an embedded controller not only on the testbench, also on the wheelchair to realize this control strategy. The designed controller is low cost and compact. M.S. in Electrical Engineering, May 2012 Show less
