With the developments of intelligent and autonomous robotic technology, robots are usually designed to confront sophisticated tasks such as automated assembly, which requires both high-speed positioning capabilities and compliance with unknown contact environments. As we know, a high-performance motion tracking control in free space can achieve efficient and accurate positioning, while impedance or force control shows superior performance in terms of sensitive force and compliance with unknown contact environments. However, it is still challenging to achieve both high-performance motion tracking and compliance within one single control framework, especially in unknown contact environments. To this end, in this article, a unified motion/force/impedance approach for unknown contact environments is proposed by robust model-reaching control with dynamic trajectory adaptation. Specifically, the overall control scheme includes two loops: the outer loop replans the trajectories of motion and force in real time to meet the environmental constraints, which are estimated by the recursive least squares estimation law; in the inner loop, the robust model-reaching control law is proposed to realize a target model, which is designed to establish a dynamic relationship between the motion and force tracking errors of the replanned trajectories. Then, by changing the matrices of the target model, the compromise between motion tracking and force tracking can be achieved, as well as different control objectives. Experiments are conducted on a seven-degree-of-freedom manipulator to validate the advantages of the proposed scheme.

中文翻译：

---

基于鲁棒模型逼近方法的未知接触环境下机械臂统一运动/力/阻抗控制


随着智能和自主机器人技术的发展，机器人通常被设计用来应对自动化装配等复杂任务，这既需要高速定位能力，又需要适应未知的接触环境。众所周知，自由空间中的高性能运动跟踪控制可以实现高效、准确的定位，而阻抗或力控制在敏感力和未知接触环境的合规性方面表现出优越的性能。然而，在一个控制框架内实现高性能运动跟踪和合规性仍然具有挑战性，特别是在未知的接触环境中。为此，在本文中，通过具有动态轨迹自适应的鲁棒模型到达控制，提出了一种针对未知接触环境的统一运动/力/阻抗方法。具体来说，总体控制方案包括两个循环：外环实时重新规划运动和力的轨迹以满足环境约束，并通过递归最小二乘估计律估计；在内环中，提出了鲁棒模型到达控制律来实现目标模型，该模型旨在建立重新规划轨迹的运动和力跟踪误差之间的动态关系。然后，通过改变目标模型的矩阵，可以实现运动跟踪和力跟踪之间的折衷，以及不同的控制目标。在七自由度机械臂上进行实验，验证了该方案的优点。