Docking control of intelligent wheelchair based on vision

A docking control method which is based on vision feedback is proposed in this paper for the intelligent wheelchair which is subject to nonholonomic motion constraints and can reconfigure between bed and wheelchair. First transform the coordinates of the line segments which are extracted in the back-view image from image coordinate system to wheelchair coordinate system by using the homography matrix. According to the Euclid features of the bed's contour, identify the U-shaped bed and calculate the posture of the intelligent wheelchair in the bed coordinate system. By using the vision feedback and dead reckoning, posture stabilization and line trajectory tracking are performed to make the intelligent wheelchair to dock into the bed portion precisely. Considering the limited input of the control system, this paper also gives a new control law for posture stabilization. Experiments validate the effectiveness and practicality of the proposed method.