As robots shift from industrial to human-centered spaces, adopting mobile manipulators, which expand workspace capabilities, becomes crucial. In these settings, seamless interaction with humans necessitates compliant control. Two common methods for safe interaction, admittance, and impedance control, require force or torque sensors, often absent in lower-cost or lightweight robots. This paper presents an adaption of impedance control that can be used on current-controlled robots without the use of force or torque sensors and its application for compliant control of a mobile manipulator. A calibration method is designed that enables estimation of the actuators' current/torque ratios and frictions, used by the adapted impedance controller, and that can handle model errors. The calibration method and the performance of the designed controller are experimentally validated using the Kinova GEN3 Lite arm. Results show that the calibration method is consistent and that the designed controller for the arm is compliant while also being able to track targets with five-millimeter precision when no interaction is present. Additionally, this paper presents two operational modes for interacting with the mobile manipulator: one for guiding the robot around the workspace through interacting with the arm and another for executing a tracking task, both maintaining compliance to external forces. These operational modes were tested in real-world experiments, affirming their practical applicability and effectiveness.

翻译：随着机器人从工业领域转向以人为中心的空间，采用能够扩展工作空间能力的移动机械臂变得至关重要。在这些场景中，与人类的无缝交互需要柔顺控制。两种常见的安全交互方法——导纳控制和阻抗控制——通常需要力或力矩传感器，而这些传感器往往在低成本或轻型机器人中缺失。本文提出了一种适用于基于电流控制的机器人且无需力或力矩传感器的阻抗控制改进方法，并将其应用于移动机械臂的柔顺控制。我们设计了一种标定方法，能够估计执行器的电流/力矩比和摩擦力（这些参数用于改进的阻抗控制器），并能够处理模型误差。使用Kinova GEN3 Lite机械臂对所提出的标定方法和控制器性能进行了实验验证。结果表明，标定方法具有一致性，且所设计的机械臂控制器在无交互时能够实现五毫米精度的目标跟踪，同时保持柔顺性。此外，本文提出了两种与移动机械臂交互的操作模式：一种是通过与机械臂交互引导机器人在工作空间中移动，另一种是执行跟踪任务，两者均保持对外部力的柔顺性。这些操作模式在实际实验中进行了测试，验证了其实际可用性和有效性。