The digital scanning collision avoidance device with risk assessment

This paper presents a new approach to digitising the Scanning Collision Avoidance Device (SCAD) which is used to detect obstacles in front of a powered wheelchair. The new approach replaced the SCAD electronic circuit with a Raspberry Pi. Python programming language is used to create a program to analyse readings from the SCAD ultrasonic transducer. The program is installed on the Raspberry Pi. An op–amp isolation circuit was inserted between SCAD and Raspberry Pi. The Raspberry Pi analysed readings received from the SCAD ultrasonic transducer. The program used the readings to identify distances and locations of obstacles in the surroundings. User input switches were connected to the Raspberry Pi and converted inputs from switches into commands controlling the wheelchair motors. The program incorporated two driving modes: Stop and Avoid. A User Interface was created to allow users to select the desired driving mode and operate the new system. Stop mode will stop the user from driving in the direction of the detected obstacle. Avoid mode will avoid the obstacles in the wheelchair surroundings by driving in the opposite direction. The Python program captured the users’ desired direction and intelligently translated these commands to a safe driving direction that avoided obstacles in the wheelchair surroundings. If the user did not select a driving mode, the program would disable the wheelchair motors and a message will appear asking the user to select a driving mode before driving. This provided a safety feature that prevented the system from being accidentally operated.