工业机器人伺服力位的混合控制研究

Research on force-position hybrid control of industrial robot

  • 摘要: 随着工业机器人的普及及其应用场景不断扩展,如何使其适应更多的应用场景成为工控领域研究的热点。在工业机器人搬运、机床上下料等场景中实现柔顺取物是机器人取物环节的研究重点。传统取物控制方法采用力控模式与位置控制模式切换的混合力位控制策略。然而,这种方法需要频繁切换控制模式,不仅增加系统复杂性,还可能降低系统稳定性和控制精度。为此,该文提出一种基于超螺旋控制的力位混合控制方案,摆脱了工业机器人位置控制模式的“强刚性”特性,使工业机器人工作在位置控制模式即可实现柔顺取物。首先推导出机器人基坐标系到末端位姿的转换矩阵;其次结合动力学模型及雅可比矩阵计算理论力矩;再通过各个关节的电流及电机、减速器等参数计算反馈力矩。在此基础上,设计了超螺旋控制器,在提高控制鲁棒性的同时,确保系统状态及其导数快速收敛到滑模面。同时设计了基于二阶低通滤波的扰动观测器,补偿至电流控制环前馈,使机器人在特定的位姿范围内稳定运行。实验表明,该文所提出的力位混合控制方案显著提升了工业机器人的柔顺取物性能,无需额外增加力矩传感器,有效降低了系统的成本和复杂度。这一方法为工业机器人在各类柔性取物场景中的应用提供了新的解决方案,具有重要的理论价值和技术意义。

     

    Abstract: With the popularization of industrial robots and the continuous expansion of their application scenarios, how to make them adapt to more application scenarios has become a hot topic in the field of industrial control research. The research focus of the robot picking process is to achieve flexible picking in scenarios such as industrial robot handling and machine tool loading and unloading. The traditional retrieval control method adopts a hybrid force position control strategy that switches between force control mode and position control mode. However, this method requires frequent switching of control modes, which not only increases system complexity but may also reduce system stability and control accuracy. Therefore, this article proposes a force position hybrid control scheme based on hyper spiral control, which eliminates the “strong rigidity” characteristic of industrial robot position control mode and enables industrial robots to work in position control mode to achieve flexible material handling. Firstly, the transformation matrix from the robot’s base coordinate system to the end pose is derived. Secondly, the theoretical torque is calculated by combining the dynamic model and Jacobian matrix. Then the feedback torque is calculated based on the current of each joint and parameters such as the motor and reducer. On this basis, a super spiral controller is designed to improve control robustness while ensuring that the system state and its derivatives converge quickly to the sliding surface. At the same time, a disturbance observer based on second-order low-pass filtering is designed to compensate for the feedforward of the current control loop, enabling the robot to operate stably within a specific pose range. The experiment shows that the force position hybrid control scheme proposed in this paper significantly improves the compliant handling performance of industrial robots without the need for additional torque sensors, effectively reducing the cost and complexity of the system. This method provides a new solution for applications of industrial robots in various flexible picking scenarios, and has important theoretical value and technical significance.

     

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