论文标题

影响感知的任务空间二次编程控制

Impact-Aware Task-Space Quadratic-Programming Control

论文作者

Wang, Yuquan, Dehio, Niels, Tanguy, Arnaud, Kheddar, Abderrahmane

论文摘要

机器人通常在刚性相对速度接近零的刚性表面上建立触点。否则,撞击引起的能量会在机器人的链接中传播,并可能对硬件造成不可逆转的损害。此外,任务空间接触速度和峰值影响力的突然变化也导致机器人关节速度和扭矩的突然变化。这会损害控制器的稳定性,尤其是对于基于平滑模型的人的稳定性。实际上,几个任务将需要建立与中等速度的接触。我们建议增强任务空间的多目标控制器,以二次程序为准,以应对三个维度的摩擦影响有弹性。我们设计了新的约束,并将通常的约束重新制定,以使其对前面提到的突然联合国家变化具有鲁棒性。一旦最佳控制搜索空间意识到:(1)构成影响后影响后关键状态的分析可行的可行集合(Polyhedra),影响事件就成为一个受控过程:(1)可行的可行性集合(Polyhedra)。在每个控制周期中,我们假设在目标接触点之前和附近,将发生在下一次迭代中。这是一个单步的预览,使我们的控制器强大地影响了时间和位置。为了评估我们的方法,我们通过熊猫机械手尝试了其对中等影响的韧性,并使用HRP-4类人动物机器人实现了快速抓取任务。

Robots usually establish contacts at rigid surfaces with near-zero relative velocities. Otherwise, impact-induced energy propagates in the robot's linkage and may cause irreversible damage to the hardware. Moreover, abrupt changes in task-space contact velocity and peak impact forces also result in abrupt changes in robot joint velocities and torques; which can compromise controllers' stability, especially for those based on smooth models. In reality, several tasks would require establishing contact with moderately high velocity. We propose to enhance task-space multi-objective controllers formulated as a quadratic program to be resilient to frictional impacts in three dimensions. We devise new constraints and reformulate the usual ones to be robust to the abrupt joint state changes mentioned earlier. The impact event becomes a controlled process once the optimal control search space is aware of: (1) the hardware-affordable impact bounds and (2) analytically-computed feasible set (polyhedra) that constrain post-impact critical states. Prior to and nearby the targeted contact spot, we assume, at each control cycle, that the impact will occur at the next iteration. This somewhat one-step preview makes our controller robust to impact time and location. To assess our approach, we experimented its resilience to moderate impacts with the Panda manipulator and achieved swift grabbing tasks with the HRP-4 humanoid robot.

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