Contact State Transitions Research Articles

Assembly Task-oriented Manipulation System(ATOMS) with Direct-drive Manipulator and Multi-task Controller.

An assembly task-oriented manipulation system (ATOMS) is proposed that monitors the changes in task process and switches task strategy accordingly. The system is divided into five functional blocks: task description, motion planning, motion execution, motion monitoring, and robot control. The assembly process is described as a series of discrete contact states and the task is programmed as sequence of motions connecting the current contact state to the next desired one. During task execution, the motion can be switched in realtime if a contact-state transition is detected. The An experimental manipulation system was developed based on the concept of ATOMS. It has a fourlayer structure, a 6-DOF direct-drive manipulator and a multi-processor, multi-task controller based on a transputer. In the second layer, a motion monitoring and evaluation (MME) module, in which the proposed detection algorithm is installed, and a motion execution management (MEM) module are simultaneously executed. The result for a square peg insertion task, programmed with a few primitive motions, in which different types of contact-state transitions occur and a position (orientation) error is introduced in the task environment, demonstrate that not only is the concept of ATOMS effective, but also that a manipulation system has the ability to execute assembly tasks with high reliability.

Petri net modelling for robotic assembly and trajectory planning

A new approach to process modelling, task synthesis, motion control and trajectory planning for robotic assembly is presented. Assembly is modelled as a discrete event dynamic system using Petri nets, incorporating both discrete and continuous aspects of the process. A process monitor based on recognizing contact state transitions is presented. A discrete event controller is developed. The controller issues velocity commands that direct the system toward the next desired contact state, while maintaining currently desired contacts and avoiding unwanted transitions. A novel means of trajectory planning which incorporates the system's ability to both monitor and control the process is given. Experimental results are given for a dual peg-in-the-hole example. The experimental results not only demonstrate highly successful insertion along the desired trajectory, but also demonstrate the ability to detect, recognize, and recover from errors and unwanted situations. >

組立作業における物体の接触状態遷移に関する運動学的解析とそのネットワーク表現の自動生成

組立作業における物体の接触状態遷移に関する運動学的解析とそのネットワーク表現の自動生成