Auto calibrated head orientation controller for robotic-wheelchair using MEMS sensors and embedded technologies

Abstract

There are many people who have lost the ability to control upper and lower limbs due to quadriplegia, paralyses or ageing side effects. This type of users requires special control systems to use an electrical wheelchair instead of using traditional control by joystick. In this paper a novel auto calibrated head orientation controller for wheelchairs and rehabilitation robotics application is proposed. The system use two Orientation Detection (OD) units, each unit includes three MEMS sensors: accelerometer, gyroscope and magnetometer which are combined together. The first OD unit reads the wheelchair orientation, which is used as a reference orientation to calibrate the system performance, when the system is faced non-straight road. The reference orientation is used to cancel the changes in orientation in case of non-straight roads and also to compensate the speed in case of ascent or descent a ramp. The second OD unit is fixed on the user's head and is used to control the speed and direction of the system. The head orientation is measured using Euler angles (Roll, Pitch and Yaw). The system movement and speed control depend on the position of the user's head related to X, Y and Z axis. The system uses powerful ARM cortex M3 microcontroller to perform the control of the intelligent application.