Study On Trajectory Planning For Youbot Robot

With the development of science and technology, the requirements of industrial robot is not only realizing to point-to-point movement, general linear movement and the curve movement, but also is achieving to move along the specified path with high speed. Therefore, we select the KUKA-Youbot from Guangdong University of Technology Robotics laboratory as a research object, deeply study on the problem of robot movement along a specified path, and aim to plan out a trajectory of robot which takes time optimal criterion into account. In this paper, the direct and inverse kinematics models are established and solved, an algorithm of B-spline interpolation is used to plan a trajectory of each joint and each wheel. With time optimal criterion, a genetic algorithm for the trajectory optimization is proposed, the robot time optimal trajectory is got finally.Firstly, this paper introduces the basic principle of the robot, matrix transformation relationship between robot end effector and the base coordinate system, and some theory of the omni-directional mobile robot kinematics model and inverse kinematics solution.Secondly, the robot kinematics model was established, the direct and inverse kinematics in detail were computed, get the relationship between the robot end effector and joints, and the relationship between mass velocity of omni-directional mobile platform center and the four wheel angular velocity, that is the mapping relationship between robot cartesian space and joint space. At the same time, use MATLAB do simulation experiment, and get the robot working space, which can prove the validity of the kinematics model.Then, use linear interpolation and circle interpolation path planning in robot cartesian space, and get robot joint space interpolation points and the wheel displacement nodes by solving the inverse kinematics. Then use three times and high order polynomial interpolation interpolate to get each joint and each wheel displacement, velocity and acceleration trajectory curve. For example, make the robot obstacle avoidance of trajectory planning.Then, this paper discusses how to use the B-spline curve in the robot time optimal trajectory planning. Write a program by MATLAB, use the B-spline interpolation get trajectory of the displacement, velocity and acceleration of each joint and each wheel. For this curve, time is the optimization goal, robot velocity and acceleration is the constraint, genetic algorithm was applied to time optimal trajectory planning, finally get optimization result of the smallest movement time.Finally, perform simulation experiment of the robot handling material motion planning, to verify the validity of the trajectory planning algorithm. Meanwhile, it achieves the robot linkage, which will improve the working efficiency of the robot In the industrial application.