Study On Trajectory Tracking Control And Motion Planning Of Mobile Manipulators

A mobile manipulator system is formed by a mobile platform and a robotic arm that fixed upon it. This system has both the advantages of mobile platform's large workspace and the dexterity of a robotic arm, and such a combination greatly extends the robot's application field. Now, mobile manipulator has already been used in a wide range of applications such as household services, industrial production and national security, etc. Therefore, the study of mobile manipulators'theoretical knowledge has a very strong practical significance. Moreover, most of mobile manipulators are redundant and non-holonomic, and these qualities bring the possibilities for robotic system to avoid singular pose and optimize its own trajectories when completing tasks. All these are important points and difficulties in the study of mobile manipulators.Up to now, there are already many progresses in the research of mobile robot and industrial robot arm, and many well-known algorithms concerning motion planning and trajectory tracking control have been developed. But in the case of a mobile manipulator, its'mobile platform and robotic arm are moving simultaneously. Since the two parts'dynamics are coupled together, their individual tracking control has a lot of disturbance. And it is central to develop new method to solve such a problem. In addition, compared to a single mobile robot or a robotic arm, the motion trajectories of mobile manipulators are composed by its'two subsystems, so the coordination of two must bring into consideration, such as how to plan the moving trajectories to achieve energy saving goal. This requires new thoughts in the motion planning of mobile manipulators. So now, we can see it is very meaningful to study the trajectory tracking and motion planning problems of mobile manipulators.This paper mainly focuses on the theoretical research perspective, using common mobile manipulators'model as research objects, designs a new method for mobile manipulator's tracking control and motion planning. For the problem of tracking control, this paper introduces a motion decoupling method into mobile manipulators'model and designs an architecture for separating the control of the mobile platform and robotic arm. In order to verify the correctness and effectiveness of this control strategy, this paper also introduces the simulation platform designed for the algorithm verification. This platform uses SIMULINK and s-function in MATLAB to simulate a mobile manipulator in the real world, which includes a forward dynamic module, a feedback loop, a control integration module and motion generation module, etc. All the simulation researches for mobile manipulator are done using this platform.Also, this paper introduces the idea of using representation space into the motion planning for mobile manipulators, which putting all the necessary variables that describe the mobile manipulator system into one the representation space, and unified motion planning and coordination are achieved. Moreover, this paper uses A-star based searching method in dealing with representation space trajectory searching, and analysis and researches are done concerning the coordination in motion planning when a mobile manipulator passing through channels.