基于扰动观测器的机械手碰撞检测与安全响应

Collision detection and safe reaction of manipulator based on disturbance observer

当机械手臂与其工作环境中的物体或人体发生碰撞时,会损坏关节处的电机或给人员带来伤害,为保证人员与设备安全,设计一种外部扰动观测器对外部碰撞作用力进行估计的方法.扰动观测器基于动量守恒推导得出,当系统不受外力时观测结果指数收敛到零附近;当系统受到外力时,观测结果指数趋近于外力大小.当观测器结果及其变化率超过一定阈值时,认为外部碰撞发生.为保证手臂及碰撞对象的安全,使控制手臂远离碰撞区域,设计了机械手臂在速度和力矩控制模式下不同的安全响应控制方法.对气球以及人身体的碰撞实验表明:该方法可以在发生接触后200ms内有效地检测到碰撞的发生,并控制机械手臂以最快速度减速直至反向运动,离开碰撞区域,保证机械手臂和人员的安全.

When a robot manipulator collides with an object or human body in its workspace,the motor on the joint would be damaged and the person would be hurt.To guarantee the safety of human body and the equipment,a disturbance observer,which is designed to evaluate the influence of the collision force,was developed.The disturbance observer is deduced from preservation of momentum.The observation result would exponentially attenuate to zero when the manipulator is not influenced by the external force,and approach to the force when it is colliding with some objects.When the observation result and its derivative exceed the given thresholds,the collision were detected.For the damage limiting of the robot or the safety of the human body,two different safe reaction methods for velocity mode and torque mode control were presented.The experiments with the collision objects,balloon and human body,were carried out.The collison could be effectively detected within 200 ms after contact and the manipulator was rapidly controlled to move reversely away from the collision region.The experimental results demonstrated that the safety of manipulator and human body could be guaranteed by the proposed collision detection and safe reaction method.