| Tasks such as serving tea are one of the most common dual-arm coordination tasks.The stability of the ends is affected by robot's movements.When the acceleration of the robot motion is too large,it will cause the slipping of the objects on the pallet,making the end unstable and increasing the risk of task failure.Therefore,it is necessary to enhance the anti-interference ability of the terminal and improve the stability.In order to reduce the possibility of sliping of the objects,an attitude optimization control algorithm is designed in this paper.For the case of controling smooth objects,a balance recovery algorithm is designed to enables the objects to maintain dynamic balance near the initial position.In order to get better results,a force control method is designed in this paper.The specific research content is as follows:Firstly,for the case of rough objects,the angle between the normal vector of the pallet plane and the force of the two arms on the pallet is chosen as the stability margin to evaluate the stability of the terminal,and the corresponding stability margin is calculated.On this basis,the control shaft is calculated in real time,and the control angle is planned through the impedance model,so that the end is approached to the best posture,so as to reduce the friction between the objects and the pallet and increase the stability of the end.When the objects are relatively smooth and smooth,the objects are easily disturbed by external disturbances and leave the initial position.In view of this situation.The ball-and-plate system with dual-arm was taken as an example for analysis.The position and velocity of the ball on the pallet are calculated based on the force sensor in the end of the dual-arm.And the position and velocity signals are filtered.With the processed results as input,the pallet control angle as output,and the balance controller is designed.Then,in order to get better results when doing coordinate tasks,it is necessary to control the contact force at the end of the robot to prevent the pre-tightening force between the arms from being too large or too small due to the initial position error,thereby affecting the completion of the task.Through experiments,the Kalman filter algorithm with better overall performance was selected to process the force sensor measurement results.After deducing the end effector gravity compensation and sensor zero drift compensation formula,the parameters and steady-state error of the impedance control algorithm are analyzed,and an integrated impedance control algorithm is proposed according to its deficiency.In order to enhance the adaptability and response speed of the algorithm,a variable coefficient integral impedance control algorithm was proposed and applied to the dual-arm cooperative force control.Afterwards,the effectiveness of the algorithm is verified by physical simulation experiments.Finally,the algorithm was verified by physical experiments and physical simulation experiments,including the end effector gravity and the sensor zero drift calibration experiment,the impedance control experiment,the integral impedance control experiment,the variable coefficient integral impedance control experiment,the dual-arm cooperative force control experiment,the attitude optimization control experiment and the terminal balance recovery control physical simulation experiment.The correctness and effectiveness of the algorithm is proved by the experimental results. |
