Research On The Working Performance And Pose Error With Sphere Joint Clearance Of The Delta Robot For Picking Operation

Delta robot is considered to be one of the most successful parallel robots in the fields of both design and application. The robot adopts the symmetrical topology structure. Because of its characteristics of large load, high speed, and high precision, it is widely used in production operation for picking and place in assembly. In this thesis, we independently develop a Delta robot(S01) for picking and place, analyze and evaluate its working performance.The main contents are as follows:First, the Delta robot prototype’s structure design and control system is introduced, the kinematic characteristic of the prototype, the working space and the Jacobi matrix analyzed. Based on the condition number of Jacobi matrix, the prototype’s manipulating performance is evaluated. Based on the law of modified trapezoid, the prototype’s trajectory planning is proposed.We adopt the virtual work principle in the rigid body dynamics modeling, establish the relationship between the input driving moment and the terminal platform’s acceleration and verify the model in simulation. According to the rated motor parameters, such as their torque, power and speed, the maximum acceleration of the trajectory is checked.Then we propose the specific methods to improve the acceleration under the motion law.We model and analyze the maximum pose error of the prototype with joint clearances. Based on Lagrange multiplier method, the spatial statics model is established. Combined with the virtual work principle, an error transfer matrix of the joints to the terminal platform is established. The error distribution is obtained by calculating the maximum pose errors of the platform.We analyze the clearance sensitivity of the platform in 3 directions.The natural frequency and vibration mode of the two kinds of prototypes are analyzed by using finite element software. Modal analysis and vibration test are carried out on the prototypes. The chirplet wavelet matching pursuit is used to decompose the vibration signals and extract time-frequency characteristics of the signals. Finally, we analyze the prototype’s kinematic characteristics through some experiments, and compare the differences between the two prototypes. Key words:Delta robot;kinematics;dynamics; trajectory planning; sphere joint clearance;...