Research On Trajectory Planning Of Self-driven AACMM

The traditional AACMM(Articulated Arm Coordinate Measuring Machine)is widely used in mechanical manufacturing,aerospace and other fields because of its small size,light weight,wide measurement range,strong flexibility and good portability.Due to the manual measurement mode of manual dragging,the measurement error caused by the instrument user cannot be controlled.With the increasing requirements of intelligent manufacturing for automatic and on-line measurement of instrument,the traditional AACMM is difficult to meet the requirement of automatic measurement on account of its poor measurement efficiency.In order to solve the problem of poor measurement efficiency,the self-driven AACMM is proposed.Combining with the beneficial achievements of the traditional AACMM and the industrial mechanical arm,the 6-DOF self-driven AACMM designed by the research group is taken as the research object and the trajectory planning of the self-driven AACMM is focused on in this paper.The kinematics of the self-driven AACMM is analyzed in this paper.With the assistant of the Modified D-H method,the kinematics model of the self-driven AACMM is established.The D-H parameters are determined,and the model proposed is verified eventually.Based on the kinematics model of the self-driven AACMM,the inverse kinematics is analyzed,which lays a theoretical foundation for the following trajectory planning.Then,according to the principle of trajectory planning and the measurement process of the self-driven AACMM,a trajectory planning method of the self-driven AACMM is proposed based on the analysis of the beneficial achievements of trajectory planning of mechanical arm.In the trajectory planning method,the probe is designed to close the measurement point in the joint space,and then transfer to Cartesian space to approach the measurement point until the measurement is completed.In joint space,the probe makes point-to-point trajectory planning to close the measurement point,and the end point speed of the probe is non-zero,which ensures that the probe can continue to move forward at the speed of the previous moment to complete the close measurement.When transfers to Cartesian space,the speed direction of the probe is consistent with the speed direction of the previous moment and continues to move forward until the probe touches the object to complete the measurement.Through analysis and comparison,five polynomial interpolation algorithm is adopted in joint space,and line interpolation algorithm is selected in Cartesian space.In this paper,the measurement process of the self-driven AACMM is simulated in MATLAB,and the trajectory planning of a sphere is simulated in the simulation environment.Finally,the proposed trajectory planning is verified with the help of virtual prototype technology in ADAMS,ANSYS and MATLAB.The rigid body model and the flexible body model of the self-driven AACMM in ADAMS software and ANSYS software are established to simulate the trajectory planning with different velocity and acceleration.The simulation result shows that the trajectory is smooth,and the trajectory planning method in this paper basically meets the design requirements.This paper also presents the static and dynamic deformation of the flexible self-driven AACMM caused by self weight and motion,which lays a foundation for the research of its control strategy.