通过优化机械臂姿态,显著降低飞行操作中碰撞带来的状态波动。
Impact-Robust Posture Optimization for Aerial Manipulation
- 基于碰撞后速度变化设计可配置的鲁棒性度量,指导姿态优化。
- 实验显示碰撞后状态波动减少最高达51%,有效避免执行器饱和。
- 适合需要高鲁棒性的空中机械臂任务,尤其依赖运动冗余的场景。
我们提出一种新方法,用于优化运动学冗余的力控机器人的姿态,以增强其在碰撞下的鲁棒性。采用刚性碰撞模型构建一个与构型相关的度量,量化碰撞前后速度的变化。通过寻找使该度量最小的构型(姿态),可在碰撞过程中显著降低机器人状态和控制命令的尖峰,提升安全性和鲁棒性。将识别鲁棒姿态的问题建模为该度量的极小极大优化问题。为克服实时求解困难,将其重构为基于梯度的运动任务,迭代引导机器人向最优构型逼近。该任务嵌入任务空间逆动力学(TSID)全机控制器中,可无缝融合其他控制目标。方法应用于执行重复点接触任务的冗余空中机械臂,在真实物理仿真器中测试,相比标准TSID,碰撞后状态波动减少最高达51%,成功避免执行器饱和。此外,通过对四足和人形机器人进行数值模拟,验证了运动冗余对碰撞鲁棒性的关键作用,状态波动最多减少45%。
原文摘要 · Abstract (English)
We present a novel method for optimizing the posture of kinematically redundant torque-controlled robots to improve robustness during impacts. A rigid impact model is used as the basis for a configuration-dependent metric that quantifies the variation between pre- and post-impact velocities. By finding configurations (postures) that minimize the aforementioned metric, spikes in the robot's state and input commands can be significantly reduced during impacts, improving safety and robustness. The problem of identifying impact-robust postures is posed as a min-max optimization of the aforementioned metric. To overcome the real-time intractability of the problem, we reformulate it as a gradient-based motion task that iteratively guides the robot towards configurations that minimize the proposed metric. This task is embedded within a task-space inverse dynamics (TSID) whole-body controller, enabling seamless integration with other control objectives. The method is applied to a kinematically redundant aerial manipulator performing repeated point contact tasks. We test our method inside a realistic physics simulator and compare it with the nominal TSID. Our method leads to a reduction (up to 51% w.r.t. standard TSID) of post-impact spikes in the robot's configuration and successfully avoids actuator saturation. Moreover, we demonstrate the importance of kinematic redundancy for impact robustness using additional numerical simulations on a quadruped and a humanoid robot, resulting in up to 45% reduction of post-impact spikes in the robot's state w.r.t. nominal TSID.
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