用力/力矩反馈在线自适应调整机器人抓取的运动模型,无需外部视觉。
Force/Torque-Based Kinematic Adaptation for Robotic Manipulation Tasks

- 仅靠关节角度和腕部力/力矩传感器,实时估计未知工具的运动关系。
- 在刚性插入时无法观测工具长度,但柔顺控制可部分激发该信息。
- 首次将控制与估计算法统一为二次规划,适合强化学习等任务策略分离设计。
接触密集型机器人操作需要精确建模机器人关节与任务感知特征之间的运动关系。这一关系通常不准确:随着工具更换或接触模式变化(如多指手在全掌抓握中非预定点接触),其关系可能瞬时改变。本文提出一种仅依赖关节角度与腕部力/力矩传感器的在线自适应方案,无需工具末端的外感知。推导出可证明稳定的运动更新律,仅从力/力矩反馈即可识别未知工具的运动学,并证明刚体与含柔顺控制器内环情况下的稳定性。结果表明,辨识仅限于运动激励方向——例如刚性插入时工具长度不可观测,而柔顺回路的被动形变可部分激发该维度;二阶阻抗控制下,连续时间条件下稳定性无条件成立。还将控制与估计联合问题建模为二次规划(QP):该形式精确给出更新律中的预测项,但无法再现跟踪适应项。仿真验证了在钉入孔任务中的有效性。本工作是未来研究计划的第一步,旨在将操作学习分解为可独立于机器人学习的任务策略(如强化学习)与在线自适应的运动学组件。
原文摘要 · Abstract (English)
Contact-rich robotic manipulation requires an accurate model of the kinematic relationship between a robot's joints and the task features it senses. This relationship is rarely known exactly: it changes with each tool the robot picks up and shifts, sometimes almost instantaneously, as contact modes change --- especially for multi-fingered hands that make and break contact at points that are not exactly prescribed, as in full-hand grasping. This paper develops an adaptive scheme that estimates that relationship online, using only joint-angle sensing and a wrist-mounted force/torque sensor, with no exteroceptive measurement of the tool tip. We derive a provably stable kinematic update law that identifies the kinematics of an unknown tool from force/torque feedback alone, and prove stability of both the rigid case and the case with a compliance controller as an inner loop. We show that identification is confined to the directions the motion excites --- so that, for example, a tool's length is unobservable under a rigid insertion push, while a compliant loop's passive yielding partially excites it; and that with a second-order admittance the compliant certificate holds unconditionally in continuous time. We also pose the combined control and estimation problem as a Quadratic Program (QP): the formulation yields the prediction term of the update law exactly but, instructively, cannot reproduce the tracking adaptation term. We validate the scheme in simulation on a peg-in-hole insertion. This work is the first step in a research program aimed at factoring manipulation learning into a task policy which can be learned in isolation of the robot, for instance by reinforcement learning, and an adaptive kinematic component that adapts online to the particular robot, hand, or tool in use.
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