A new space used in sensor-less manipulation

An autonomous robotic manipulator can reduce the uncertainty in the locations of the objects by sensing, by motion strategies or by both. Compared with manipulation with sensors, sensor-less manipulation can provide a simple method to eliminate the uncertainty and can also avoid all the problems caused by sensors. Sensor-less motion carried out (i) to achieve high-precision tasks and (ii) in three-dimensional space is considered too difficult. The limited application range of sensor-less manipulation is regarded as its major disadvantage with respect to the strategies with sensors used. Robotic peg-hole assembly, as the most common mechanical automated task, is a long-standing problem in robotics. In our previous work, several strategies for the robotic peg-hole assembly were designed and were applied to experiments successfully. These strategies can program the robots to perform the assembly in three-dimensional space with the precision higher than that of the robots being used, without additional devices such as force sensors or flexible wrists. The approach provided a good example of the high-precision sensor-less manipulation in three-dimensional space. The purpose of this paper is not to design new strategies in robotic assembly. It provides a logical method in sensor-less motion planning and applies it to robotic assembly. Many strategies used in Inoue's (1979) work in robotic assembly with force sensors and our previous work in robotic assembly without force sensors are derived from this basic premise and other new strategies can be designed. It is expected that sensor-less motion planning can be investigated for many a wide variety of tasks based on this approach.