Research On Trajectory Planning Of Excavator Manipulator

Trajectory planning of manipulator is the premise and foundation for manipulator control, and the main purpose is to ensure the smooth and stable movement by planning angle,velocity,acceleration and jerk during its motion. On the other hand, it can also avoid shock and vibration during the work, thus it can improve the reliability and efficiency of manipulator. In this paper, it takes the excavator model as research object and studies its inverse kinematics. Based on the result, this paper also studies the trajectory planning method in joint space.Based on the analysis of the excavator structure and its motion, a standard D-H method is taken to establish its mathematical model. Accroding to the kinematics knowledge, kinematics analysis is also executed, the relationship between bucket posture and joint position is acknowledged. Then according to the actual objectives given, this paper realizes the solve of the excavator inverse kinematics problem by geometric method, and compared to the traditional matrix transform method, the calculation process is easier. On this basis, the manipulator trajectory planning and some related issues are briefly described in this paper, and in connection with the characteristics of excavator action, a detailed analysis of the establishing process of the excavator cubic polynomial interpolation function in joint space is given. Then, time-optimal trajectory planning of excavator can be carried out.In the trajectory planning process, the three joint kinematic constraints need to be taken as the trajectory constraints and then, cubic polynomial trajectory function expressions which satisfied the constraints can be solved. But the existing fitness function has not been connected with constraints, it will cause the shortcomings such as long searching time, can not find the solution to meet the conditions which may occur in dealing with constraints by intelligent optimization methods. The treatment for constraints is combined with the construction of fitness function in this paper and a new fitness function which can ensure the joint trajectory satisfied constraints is established. Another advantage of this fitness function is that it can also ensure the trajectory meet time-optimal performance, then the minimum value of this function will be adapted by PSO. By comparison with the existing algorithm, the result shows that the entire optimization process of the algorithm in this paper is less time-consuming, higher success rate.In order to verify the usefulness of the content in this paper, the simulation model of the excavator is built in MATLAB SimMechanics module depending on its configuration. The trajectory planning is integrated into the simulation process, and the correctness of trajectory planning is verified by the simulation results. In order to verify the practical effect more in-depth, the excavator control system is modified and the hardware and software design of control system which is based on DSP F2812is developed, in the meanwhile, the excavator control through DSP is also achieved. Then the experiments such as motion path projection of excavator bucket and actual shoveling soil are conducted,and the experimental results verify the validity and usefulness of trajectory planning.