arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1801.02151cs.RO
收藏

基于时间投影控制的步进式Push恢复策略

Push recovery with stepping strategy based on time-projection control

EPFL(洛桑联邦理工学院)

Salman Faraji, Hamed Razavi, Auke J. Ijspeert

摘要:

在本文中,我们提出了一个简单的控制框架与动态步进性能的在线推送恢复。由于我们的机器人腿相对较重,我们需要考虑摆动动力学,因此使用一个称为3LP的线性模型,该模型由三个关节组成,以模拟摆动和躯干动力学。基于3LP方程,我们制定离散LQR控制器,并使用一个特定的时间投影方法来调整下一个足迹的位置在线连续的运动过程中。这种基于骨盆和摆动脚跟踪误差的调整自然会考虑摆动动力学。建议的调整被添加到笛卡尔3LP步态,并通过逆运动学转换为关节空间轨迹。固定和自适应的脚抬起策略也确保了在扰动的步行条件下有足够的离地间隙。所提出的结构是鲁棒的,但使用非常简单的状态估计和基本的位置跟踪。我们依靠物理串联弹性致动器来吸收冲击,同时引入简单的法律来补偿其跟踪偏差。大量的实验证明了不同的控制块的功能,并证明了时间投影在极端推恢复场景的有效性。我们还显示自产和紧急行走步态时,机器人受到持续的拖曳力。这些步态的特点是动态步行鲁棒性,由于相对柔软的弹簧在脚踝和避免任何零力矩点(ZMP)控制,在我们提出的架构。

英文摘要:

In this paper, we present a simple control framework for on-line push recovery with dynamic stepping properties. Due to relatively heavy legs in our robot, we need to take swing dynamics into account and thus use a linear model called 3LP which is composed of three pendulums to simulate swing and torso dynamics. Based on 3LP equations, we formulate discrete LQR controllers and use a particular time-projection method to adjust the next footstep location on-line during the motion continuously. This adjustment, which is found based on both pelvis and swing foot tracking errors, naturally takes the swing dynamics into account. Suggested adjustments are added to the Cartesian 3LP gaits and converted to joint-space trajectories through inverse kinematics. Fixed and adaptive foot lift strategies also ensure enough ground clearance in perturbed walking conditions. The proposed structure is robust, yet uses very simple state estimation and basic position tracking. We rely on the physical series elastic actuators to absorb impacts while introducing simple laws to compensate their tracking bias. Extensive experiments demonstrate the functionality of different control blocks and prove the effectiveness of time-projection in extreme push recovery scenarios. We also show self-produced and emergent walking gaits when the robot is subject to continuous dragging forces. These gaits feature dynamic walking robustness due to relatively soft springs in the ankles and avoiding any Zero Moment Point (ZMP) control in our proposed architecture.

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。

↑