In this study, by considering a space-based, n-joint manipulator system as research object, a kinematic and a dynamic model are constructed and the system’s nonholonomic property is discussed. In light of the nonholonomic property unique to space-based systems, a path planning method is introduced to ensure that when an end-effector moves to the desired position, a floating base achieves the expected pose. The trajectories of the joints are first parameterized using sinusoidal polynomial functions, and cost functions are defined by the pose deviation of the base and the positional error of the end-effector. At this stage, the path planning problem is converted into a target optimization problem, where the target is a function of the joints. We then adopt a quantum genetic algorithm (QGA) to solve this objective optimization problem to attain the optimized trajectories of the joints and then execute nonholonomic path planning. To test the proposed method, we carried out a simulation on a six-degree-of-freedom (DOF) space-based manipulator system (SBMS). The results showed that, compared to traditional genetic optimization algorithms, the QGA converges more rapidly and has a more accurate output.
In this paper, combining with the engineering reality needs, we developed a new type of friction stir welding robot welding system. Through the configuration analysis, introduces the structural components and functional roles of each part of the FSW robot, as well as the commonly used five kinds of typical working-conditions. Using D-H parameters method, establishment the forward kinematics equation of FSW robot and verify its rightness. With Piper criterion method, solve the inverse solution of FSW robot's kinematics equation. Finally, take melon petals welding condition for example, carry out trajectory planning for a given size rockets head weld and conduct welding simulation analysis. We have got different parameters' change curves relative to time on FSW robot's joint space and verified the correctness of its mechanism design and kinematics model
Abstract-Compared with the fixed-base manipulator system, kinematical and dynamical modeling and control of free-floating manipulator system (SBMS) becomes much more complicated. The primary cause is that there exists a deep dynamical coupling relationship between the floating base and the manipulator mounted on it. Firstly, in this article, generalized equation of motion of an n-DOF SBMS is built. Secondly, relevant attitudes of generalize coefficient matrixes, such as dynamical manipulability, are discussed. Then, in order to make the joints well follow a desired trajectory designed beforehand, a modelbased control method is proposed aiming at a 6-DOF SBMS. Finally, a simulation test is conducted to demonstrate effectiveness of the method mentioned above.
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