Research On Obstacle Avoidance Trajectory Planning And Motion Control Of The Mechanical Arm Therapy Bed

As the studies of clinical application show,the main factors that restrict the effect of radiotherapy in clinical application at present are the low accuracy of the positioning guide and accurate location of patients.Mechanical arm therapy bed as a support device for patients in the course of treatment.The collision-free motion of mechanical arm therapy bed in the workspace is the first prerequisite to ensure the precision of pendulum guidance and accurate positioning.Therefore,according to the motion interference of obstacles to the mechanical arm therapy bed in the treatment room.How to ensure the collision-free movement of the end actuator of the mechanical arm therapy bed from the initial position to the end position has become a high challenge.This subject is based on the collision-free trajectory planning and motion control of the mechanical arm therapy bed.First of all,the kinematics model and collision interference model of mechanical arm therapy bed are established.On the basis of the analysis,the requirements of motion efficiency and real time performance of clinical application to mechanical arm therapy bed are analyzed.A genetic algorithm based trajectory planning method for obstacle avoidance of space manipulator is proposed,and the trajectory tracking control of mechanical arm therapy bed is studied.(1)According to the mechanical structure characteristic of the mechanical arm therapy bed.The establishment of a forward kinematic model of a therapy bed by D-H representation.On this basis,the inverse kinematics solution is solved by analytic method.The trajectory planning of mechanical arm therapy bed is carried out.(2)A collision interference model was established on the basis of the motion interference of the obstacles in the treatment room to the mechanical arm therapy bed.It is assumed that the ideal trajectory of the mechanical arm in joint space is described by two polynomial curves.By adjusting the connecting points of the two polynomial curves,the trajectory of the end actuator of the mechanical arm can avoid obstacles.Then the parameter equation about the middle point is established,and the genetic algorithm is used to solve the problem.On this basis,the fitness evaluation function of the end trajectory length,running time and joint maximum torque of the mechanical arm is established.Thus,an ideal trajectory with nocollision,good dynamic characteristics,short trajectory length and motion time is designed.(3)According to the interference of obstacles in the treatment room to the movement of the mechanical arm therapy bed.In order for the end actuator of the mechanical arm to move along the predetermined path.A robust controller is designed to be used in mechanical arm therapy bed.Simulation results show that the system can track the desired trajectory with small steady-state error.It ensures the collision-free accurate control of the end actuator of the mechanical arm therapy bed from the initial position to the end position and can make the joints run smoothly.(4)In order to observe and verify the forward kinematics model and the inverse kinematics solution and trajectory planning of mechanical arm therapy bed directly.The graphical user interface of a mechanical arm therapy bed is established by MATLAB GUI.The interface mainly uses the Robotics Toolbox in MATLAB to verify the above theory.