Active Vapor-Based Robotic Wiper

This paper presents a method of normal estimation for mirrors and transparent objects, which are difficult to recognize with a camera. To create a diffuse reflective surface, we propose to spray the water vapor onto the transparent or mirror surface. In the proposed method, we move an ultrasonic humidifier equipped on the tip of a robotic arm to apply the sprayed water vapor onto a plane of a target object so as to form a cross-shaped misted area. Diffuse reflective surfaces are partially generated as the misted area, which allows the camera to detect a surface of the target object. The viewpoint of the gripper-mounted camera is adjusted so that the extracted misted area appears as largest in the image, and finally the plane normal of the target object surface are estimated. We conducted normal estimation experiments to evaluate the effectiveness of the proposed method. The RMSEs of the azimuth estimation for a mirror and a transparent glass are about 4.2 and 5.8 degrees, respectively. Consequently, our robot experiments demonstrate that our robotic wiper can perform contact-force-regulated wiping motions for cleaning a transparent window as humans do.