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对于空间装配等与环境进行交互的任务,迫切要求空间机器人具有力控制的能力。利用机器人的关节力矩传感器,提出了一种新型的基于阻抗内环的力外环控制策略。在该方法中,内环采用阻抗控制代替传统的位置控制。阻抗控制内环使机器人具有一定的柔顺性,力外环通过期望力与实际力的误差对内环的参考轨迹进行修正,实现了机器人的力跟踪控制。另外,为了验证利用关节力矩传感器间接测量末端接触力的效果,机器人末端安装了一个高精度的JR3腕力传感器用来直接测量实际接触力。在基于位置内环和阻抗内环的力外环控制方式下,进行了机器人接触刚度变化较大环境(海绵、泡沫和铁块)的力跟踪实验。实验表明,当环境刚度变化较大时,相对于传统的力外环方法,本文提出的方法能够实现稳定的力跟踪性能。尤其对于铁块这种刚度很大的环境,该方法的有效性更加明显。
For tasks such as space assembly and environment interaction, the space robot is urgently required to have the ability of force control. Using the robot joint torque sensor, a new type of force outer ring control strategy based on impedance inner ring is proposed. In this method, the inner loop uses impedance control instead of the traditional position control. Impedance control of the inner ring makes the robot have a certain flexibility, the force outer ring through the expected force and the actual error of the inner reference trajectory correction, to achieve the robot’s force tracking control. In addition, in order to verify the effect of indirectly measuring the end contact force using the joint torque sensor, a high-precision JR3 wrist force sensor is installed at the end of the robot to directly measure the actual contact force. In the force outer ring control method based on the position inner ring and the impedance inner ring, the force tracking experiment of the robot with large change of contact stiffness (sponge, foam and iron block) was carried out. Experiments show that the proposed method can achieve stable force tracking performance compared with the traditional force-outer-ring method when the variation of environmental stiffness is large. Especially for the rigid environment of iron, the effectiveness of this method is more obvious.