Over the years, the health service sector has been continually trying to improve the service provided to the aging population, accident victims and people in need of mobility assistance. As a result, more emphasis is being directed towards the design and development of intelligent tools (e.g. such as the robotic wheelchairs) which bring multiple functions, high stability and safety to help accident victims and people in need of mobility assistance.
Robotic wheelchair is an amalgamation of intelligent robotics technology and an electric wheelchair. It is a kind of enhanced wheelchair that has capabilities of navigating, detecting obstacles and moving automatically by utilizing sensors and artificial intelligence.
Such a system is made up of three main sub-systems, which include environmental awareness and navigation, motion control and human-machine interface.
Environmental awareness and navigation subsystem is built with image, sonar and infrared sensors. Because sonar sensors have the disadvantage of wide beam angle, non-directionality and ghost echo, infrared sensors are used as a co-sensor for obstacle detection to compensate for the former’s shortcomings. Image sensors offer visual navigation function by capturing images of surroundings and comparing with pre-stored map or monitoring the user’s eyeball / head movement to determine moving direction of wheelchair.
Motion control subsystem consists of MCU, accelerometers, motor drivers, rotary encoders and motors. Rotary encoders and 3-axis accelerometers monitor the speed and orientation of the wheelchair when changing direction and climbing ramps. They work with MCU, motor drivers and motors to implement motion control.
Keypad, microphone, joystick, and touch screen constitute a human-machine interface of robotic wheelchairs. Keypad is used to select manual, semi-automatic, or automatic navigation mode. Microphone receives voice instructions to control motion of wheelchairs. But so far, robotic wheelchairs can only recognize a few instructions such as ‘go forward’, ‘go back’, ‘turn left’ and ‘turn right’. Joysticks are used in manual navigation mode to control wheelchair’s motion. Touch screen allows users set parameters such as speed or the destination that needs to be specified in automatic navigation mode.
Robotic wheelchairs are becoming more and more intelligent and human-like. In the future, highly advanced technologies such as brain wave control and robotic arm could be equipped on robotic wheelchair to help more people in need of mobility support around the world.