Attitude control of planar end-effector and estimation of contact point using parallel mechanism

Recently, many robots have been utilized in unknown environment, for example, slave robots of teleoperation systems, walking robots and so on. They are called environment-adaptive robots. It is very important for the environment-adaptive robots to contact stably and to recognize unknown environment. In this paper, a compliance controller of attitude of a planar end-effector is proposed to achieve stable contact with unknown environment. The robot utilized in this research has parallel mechanism as a whole, since the planar end-effector is supported by three arms. With the assumption that only face-to-point contact exists between the end-effector and unknown environment, an estimation method of the contact point without sensors is also proposed. Moreover, excessive stress is not exerted on the robots and the environment by means of the controller we propose, when the contact point is estimated. Our new approach of contact motion can be widely applied to the robots using parallel mechanism. The validity of the proposed method is shown by the numerical and experimental results.