Collision Avoidance Path Planning Based On External Observer

Faced with areas such as supply chain/logistics and manufacturing,which require robots to work with operators.Safety has been put at the forefront of current robotics research in the face of an increasing number of robot accidents.When the end of the manipulator performs tracking on the desired trajectory,collision recognition and position feedback are usually through external sensors.It not only increases the cost of the robot and the complexity of the control system,but also external sensors are subject to varying degrees of interference in harsh environments,or even unable to complete the task.For example,the vision sensor cannot work normally in low visibility environments such as dense fog and darkness.Therefore,this paper designs an obstacle avoidance path planning for a manipulator based on the external force observer.The research object is a planar three degree-of-freedom manipulator,and its corresponding kinematics and dynamics equations are established.The external force observer is constructed based on dynamics to identify the accidental collision of the manipulator.Based on the blind tactile groping environment,the post-collision control strategy is designed and used for the improved master-slave task transformation obstacle avoidance algorithm.Without the use of external sensors,the manipulator can still passively avoid unexpected obstacles and reach the target position according to the desired trajectory.The main content of this article is as follows:First,the model of the dynamics and kinematics of the manipulator are established.Using the D-H method to analyze the positive kinematics from the base to the end of the manipulator.We tried to derive the inverse kinematics of the manipulator using algebraic solutions.The speed kinematics of the manipulator is solved by the Jacobian matrix.The dynamic equilibrium equation of the manipulator is established according to the Lagrange method,and the specific model parameters of the planar three-link manipulator are further deduced.Secondly,the external force observer based on dynamics.The actual motor drive torque is obtained from the actual motor drive current of the manipulator joint,and the estimated value of the motor drive torque is obtained by substituting the expected angle,angular velocity and angular acceleration of the joint into the dynamic model.The difference operation of these two values establishes the observation value of the external force observer to identify the external force.The actual motor drive current is preprocessed by switching recursive average filter,and the dynamic threshold is set for the external force observer based on dynamic.Thirdly,obstacle avoidance path planning of manipulator based on heuristic perception.The external force observer cannot effectively obtain the precise position and shape information of the obstacle during the collision of the manipulator,and the post-collision control strategy for heuristic sensing is designed.When there is recognition to external forces,the control system was quick to adopt a similar touch the blind groping way of environment to multiple tentative obstacle avoidance of obstacles.It effectively reduces the risk of danger or potential.The obstacle avoidance path planning of manipulator is based on improving the obstacle avoidance algorithm of master-slave task transformation.Finally,experimental research on collision detection and obstacle avoidance path planning of manipulator.It combines the corresponding equipment to build the hardware environment and software environment.It conducts experiments on external force observers and obstacle avoidance path planning based on heuristics.The research results show that the algorithm proposed in this paper can make the manipulator achieve obstacle avoidance and trajectory tracking without the aid of external sensors,and ensure the safety of the human and the manipulator under unknown multiple obstacles.