论文标题
移动基础刚性机器人动力学的有效几何线性化
Efficient Geometric Linearization of Moving-Base Rigid Robot Dynamics
论文作者
论文摘要
机器人系统方程式有关给定状态输入轨迹的运动方程式(包括受控平衡状态)是基于模型的计划,闭环控制,增益调整和状态估计的有价值工具。与具有棱柱形或旋转接头的基于固定的机械手的情况相反,移动碱机器人系统(例如人形生物,四倍的机器人或空中操纵器)的状态空间不能通过有限数量的独立坐标来全局参数。这种不可能的直接结果是这些系统的状态包括系统的全局取向,正式被描述为特殊正交组的元素(3)。结果,从实际角度来看,通过例如通过欧拉或cardan角度来局部对系统的态度进行局部参数来解决这些系统运动方程的线性化。但是,这是引入人工参数化奇点和额外的衍生计算的缺点。在这项贡献中,我们表明实际上可以定义一个线性化的概念,该概念不需要将局部参数化用于系统的方向,从而获得数学上优雅,递归且无奇异性线性化的基于移动的机器人系统。尤其是通过提出现有递归算法的非平凡修改来获得递归性,以允许对反动力学的几何导数和机器人系统质量基质的逆计算。通过数值比较与通过几何有限差异获得的结果对所提出算法的正确性进行了验证。
The linearization of the equations of motion of a robotics system about a given state-input trajectory, including a controlled equilibrium state, is a valuable tool for model-based planning, closed-loop control, gain tuning, and state estimation. Contrary to the case of fixed based manipulators with prismatic or rotary joints, the state space of moving-base robotic systems such as humanoids, quadruped robots, or aerial manipulators cannot be globally parametrized by a finite number of independent coordinates. This impossibility is a direct consequence of the fact that the state of these systems includes the system's global orientation, formally described as an element of the special orthogonal group SO(3). As a consequence, obtaining the linearization of the equations of motion for these systems is typically resolved, from a practical perspective, by locally parameterizing the system's attitude by means of, e.g., Euler or Cardan angles. This has the drawback, however, of introducing artificial parameterization singularities and extra derivative computations. In this contribution, we show that it is actually possible to define a notion of linearization that does not require the use of a local parameterization for the system's orientation, obtaining a mathematically elegant, recursive, and singularity-free linearization for moving-based robot systems. Recursiveness, in particular, is obtained by proposing a nontrivial modification of existing recursive algorithms to allow for computations of the geometric derivatives of the inverse dynamics and the inverse of the mass matrix of the robotic system. The correctness of the proposed algorithm is validated by means of a numerical comparison with the result obtained via geometric finite difference.