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arXiv 2109.07705cs.ROcs.SYeess.SY
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人形机器人全身柔顺性的混合控制

Mixed Control for Whole-Body Compliance of a Humanoid Robot

Beijing Research Institute of UBTECH Robotics(优必选机器人北京研究院);Tsinghua University(清华大学)

Xiaozhu Ju, Jiajun Wang, Gang Han, Mingguo Zhao

摘要:

层次二次规划(HQP)通常用于考虑多任务的严格层次性和机器人在全身柔顺过程中的物理不等式约束。然而,对于一步HQP,当它接近约束边界时,解会振荡。这是因为边界的突然撞击会产生无法实现的颠簸,甚至是不可行的解决方案。针对这些不足,本文提出了一种混合控制方法,将单轴模型预测控制(MPC)和比例微分(PD)控制相结合,实现对整个机构的柔顺性控制。预测控制器预测关键任务的边界与控制目标之间的距离,并通过预先预测和优化提供平滑可行的解决方案。然而,应用MPC将不可避免地增加计算时间。因此,为了实现500 Hz伺服速率,PD控制器仍然调节其他任务以节省计算资源。此外,我们使用一个更有效的零空间投影(NSP)全身控制器,而不是HQP和分布的单轴MPC到四个CPU核心的并行计算。最后,通过仿真和在人形机器人Walker X上的实验,验证了所提出策略的性能。

英文摘要:

The hierarchical quadratic programming (HQP) is commonly applied to consider strict hierarchies of multi-tasks and robot's physical inequality constraints during whole-body compliance. However, for the one-step HQP, the solution can oscillate when it is close to the boundary of constraints. It is because the abrupt hit of the bounds gives rise to unrealisable jerks and even infeasible solutions. This paper proposes the mixed control, which blends the single-axis model predictive control (MPC) and proportional derivate (PD) control for the whole-body compliance to overcome these deficiencies. The MPC predicts the distances between the bounds and the control target of the critical tasks, and it provides smooth and feasible solutions by prediction and optimisation in advance. However, applying MPC will inevitably increase the computation time. Therefore, to achieve a 500 Hz servo rate, the PD controllers still regulate other tasks to save computation resources. Also, we use a more efficient null space projection (NSP) whole-body controller instead of the HQP and distribute the single-axis MPCs into four CPU cores for parallel computation. Finally, we validate the desired capabilities of the proposed strategy via Simulations and the experiment on the humanoid robot Walker X.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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