Time-optimal Trajectory Planning Algorithms Design For Industrial Robots

With the development of strategic guidelines such as China's manufacturing of 2025 and Industry 4.0,the industrial robots have played an important role in the industrial intelligent production.However,The key factor of whether industrial robots can replace manual or industrial automation equipment is whether industrial robots can increase production efficiency,improve product quality,and reduce production costs.In terms of how to increase the production efficiency,the trajectory of the industrial robot can be optimized to shorten the running time of the trajectory,thereby improving the work efficiency of the robot..For example,when an industrial robot carries out an automobile frame welding operation,this method can be applied to improve the work efficiency of the robot.In this thesis,the problem of optimal trajectory planning for industrial robots with specified trajectory nodes is studied.After reviewing the existing related literature,it is found that there are still several major issues that need further solution.First,the robot trajectory is mathematically expressed in a complex way.The analytic method cannot be used to obtain the extremum points of the trajectory function and its derivative functions when calculating the trajectory kinematic constraints.Using numerical solutions will increase the running time of the optimization algorithm.The second problem is that the optimization results in the literature still have a certain space for improvement.The third chanllege is that most commercially industrial robots are unable to meet the experimental needs of trajectory planning research.It leads researchers to fail to use the designed trajectory for actual robot system verification.Motivated by solving these three problems,this dissertation will carry out a detailed investigation.The main work of this thesis is related to the following three aspects.(1)To solve the first problem and to use the analytical method to calculate the trajectory constraints with the objective of shortening the time spent in calculating the kinematic constraints achieved.First,the trajectory interpolation methods commonly used in joint space trajectory planning are investigated,and the interpolation methods of cubic polynomials and quintic polynomials are introduced in detail.Then,the polynomial is chosen five times to construct the trajectory function of the robot,and the trajectory interpolation method between multiple nodes is deduced,and the values of velocity and acceleration at the start and end points of the trajectory are simultaneously configured.Finally,the analytical expressions of the extremum of the quintic polynomial trajectory function and its derivative are solved by MATLAB,and the purpose of solving the extremum of the trajectory function and its derivative is solved by analytical method.(2)Regarding the second problem,in order to obtain better time optimal trajectory planning results,this dissertation selects the genetic algorithm and designs the individual fitness function of the population.Taking the joint position constraints,velocity constraints,acceleration constraints,and jerk constraints of the manipulator into account,the trajectory optimization calculation of the constructed fifth-order polynomial trajectory with the minimum time is optimized.The optimized trajectory position,velocity,acceleration,and second-order acceleration curve are smooth and continuous,and the values of velocity and acceleration at the start and end points of the entire trajectory are all zero.(3)Aiming at meeting the experimental needs of the research on trajectory planning of industrial robots,a robot motion control system that allows researchers to study the motion control and trajectory planning of industrial robots is presented.This paper presents a set of custom trajectory motion control solutions for industrial robots.By constructing an actual industrial robot control system,a custom trajectory motion control interface was developed.The developed interface can be easily manipulated to realize the motion control of the specified custom trajectory.The actual function of the custom trajectory motion control interface was finally verified through experimental testing.