For dismantling heavy structure under special environment in radioactivity, there are many problems which should be tele-operated and feedback a cutting force for cutting a thick structure such as concrete. When operator dismantles a thick heavy concrete structure, it is in sufficient to judge whether robot is contacting or not with environment by using only vision information. To overcome this problem, force feedback and impedance model based bilateral control are introduced. The sliding mode control with sliding perturbation observer (SMCSPO) based bilateral control is applied and surveyed to a single rod hydraulic cylinder in this paper. The sliding mode control is used for robustness against a disturbance. The sliding perturbation observer is used for estimation of a reaction force such as cutting force. The bilateral control is executed using the information of reaction force estimated by SMCSPO. The contribution of this paper is that the estimation method and bilateral control of the single rod hydraulic cylinder are introduced and discussed by experiment.

Though the final goal of mobile robot navigation is to be autonomous, operators intelligent and skillful decisions are necessary when there are many scattered obstacles. There are several limitations even in the camera-based tele-operation of a mobile robot, which is very popular for the mobile robot navigation. For examples, shadowed and curved areas acnnot be viewed using a narrow view-angle camera, especially in bad weather such as on snowy or rainy days. Therefore, it is necessary to have other sensory information for reliable tele-operations. In this paper, sixteen ultrasonic sensors are attached around a mobile robot in a ring pattern to measure the distances to obstacles. Acollision vector is introduced in this paper as a new tool for obstacle avoidance, which is defined as a normal vector from an obstacle to the mobile robot. Based on this collision vector, a virtual reflection force is generated to avoid the obstacles and then the reflection force is transferred to an operator who is holding a joystick to control the mobile robot. Relying on the reflection force, the operator can control the mobile robot more smoothly and safely. For this bi-directional tele-operation, a master joystick system using a hall sensor was designed to resolve the existence of nonlinear sections, which are usual for a general joystick with two motors and potentiometers. Finally, the efficiency of a force reflection joystick is verified through the comparison of two vision-based tele-operation experiments, with and without force reflection.