Research And Implementation Of The Service Robot Dual-arm Coordinated Manipulation

Service robot which provides necessary service for people in unstructured environment is an integrated system of multi-high technology. A service robot like human beings must have two arms. Dual-arm coordinated manipulation is an efficient path in improving the operation and loading capabilities, enhancing the reliability, and expanding operation space of robot system. Dual-arm coordinated manipulation is a very important direction in robot research area at all times.This subject belongs to the State High-Tech Development Plan (863 program) of China—Multi-robot system for family life support. Taking"Research and Implementation of the Service Robot Dual-arm Coordinated Manipulation"as a main topic and two arms of the service robot developed by our team as the research object, this doctoral dissertation is aimed at exploring the mechanics of motion and control of service robot dual-arm coordinated manipulation, and realizing human-like motion in manipulation. The research content mainly includes dual-arm kinematics and calibration, dual-arm coordinated motion, dual-arm human-like movement planning, Petri Net modeling of dual-arm coordinated manipulation, etc. They are described in detail as follows:1) A dual-arm system with the feature of light-weight and control system opening is established. Because most of conventional robots are very heavy and their controllers are designed with closed natures, they are not suitable for service robot arms. This dissertation uses a kind of modular joint whose control code is opening to form the robot arms and the weight of the whole service robot is lightened sharply. On the basis of hardware system connection and according to the modular functional character of the joint, the distributed control system is designed for two arms.2) In view of understanding easily and real time, the dual-arm kinematics is solved. The dual-arm is calibrated with a method of relative error model. The direct kinematics is computed after the structure parameters of dual-arm are described with DH convention method. In the process of solving inverse kinematics, because the pure algebra method is not easy to find independent irrelevant variable equations, the first three joints of arm are solved using geometry method, and the last three joints of arm are solved using algebra method. The correctness and timeliness are validated by software developed based on VC++. To improve precision, the relative error mathematic model is established, and the arms are calibrated by a laser tracker.3) The method of one arm trajectory planning is finished and the constrained relations of dual-arm four coordinated motions are analyzed deeply. The LSPB interpolation method is used to plan the trajectory in joint space and the line and arc interpolation method is used in Cartesian space. To make a more well-distributed motion, the quaternion is employed to plan the arm pose. A closed kinematics chain mechanism is formed between two arms and the object. Holding a rigid-body object, handling a pair of pliers, handling an object with a spherical joint and assembling a bolt are discussed deeply. According to the initial state and motion condition of the master arm, the speed of slave arm is computed. Dual-arm coordinated motion is finished by the control mode of master-slave following pattern. To control the arms, instructions and a soft teach pendant is developed.4) From a point of neurophysiology, the initial pose of service robot dual-arm is optimized and the mathematics model of dual-arm human-like pose is established. To produce human-like pose, the structure, freedoms and motion mechanism of human arm are analyzed. The initial installation pose is optimized according to investigation result of neurophysiology and characteristic of the service robot two arms. Based on modifying a sensorimotor transformation model of human arm, this thesis gets the mathematics model of the service robot dual-arm human-like pose.5) The Petri Net models of one arm and dual-arm are established and the basic capability is analyzed. Based on that, the control structure of dual-arm coordinated manipulation is designed. According to the characteristic of arm manipulation, two arm manipulations can be classified in coordinated and uncoordinated tasks. Using the reachability graph method, the model is analyzed and the conclusion that the net is bounded, live and conservative is obtained. The hierarchical control structure with Petri Net model as the task coordination layer is developed.6) In order to verify the proposed algorithms and methods, a series of experiments aiming at ordinary service and entertainment in family daily life are carried out, which demonstrate the reliability of hardware and stability of software. The results prove the feasibility of the dual-arm system, but the dual-arm system still need be improved for human-like motions and coordinated manipulations.The contribution of the dissertation consists in improving the capability of motion and manipulation, the extent of human-like motion and stability of service robot dual-arm and widening application field. This is of positive academic significance and practical importance to improve the quality of service robot dual-arm coordinated manipulation.