论文标题
有效学习自适应计算扭矩控制的反向动力学模型
Efficient Learning of Inverse Dynamics Models for Adaptive Computed Torque Control
论文作者
论文摘要
准确地建模机器人动力学对于控制,运动优化和安全的人类机器人协作至关重要。鉴于现代机器人系统的复杂性,动力学建模仍然是非平凡的,主要是在符合性的执行器,机械不准确性,摩擦和传感器噪声的情况下。最近的努力集中在利用数据驱动的方法(例如高斯流程和神经网络)来克服这些挑战,因为它们能够捕获这些动态而无需事先进行广泛的知识。尽管高斯流程已经证明是一种学习机器人动力学的有效方法,并能够通过其差异来代表学习模型中的不确定性,但它们以立方时代的复杂性而不是线性为代价,就像深层神经网络一样。在这项工作中,我们利用了深内核模型的使用,该模型将深度学习的计算效率与内核方法的非参数灵活性(高斯流程)结合起来,以及实现不确定性量化的准确概率框架的高度目标。通过使用预测的差异,我们将反馈的收益适应了更准确的模型,从而导致低增益控制而不会损害跟踪精度。使用从七个自由度机器人操纵器中记录的模拟和真实数据,我们说明使用随机变化推断与深核模型如何提高计算的扭矩控制器中的合规性,并保留跟踪精度。我们从经验上展示了我们的模型如何以在线逆动力学模型学习的预测不确定性并巩固其对不同设置的适应和概括能力的预测不确定性。
Modelling robot dynamics accurately is essential for control, motion optimisation and safe human-robot collaboration. Given the complexity of modern robotic systems, dynamics modelling remains non-trivial, mostly in the presence of compliant actuators, mechanical inaccuracies, friction and sensor noise. Recent efforts have focused on utilising data-driven methods such as Gaussian processes and neural networks to overcome these challenges, as they are capable of capturing these dynamics without requiring extensive knowledge beforehand. While Gaussian processes have shown to be an effective method for learning robotic dynamics with the ability to also represent the uncertainty in the learned model through its variance, they come at a cost of cubic time complexity rather than linear, as is the case for deep neural networks. In this work, we leverage the use of deep kernel models, which combine the computational efficiency of deep learning with the non-parametric flexibility of kernel methods (Gaussian processes), with the overarching goal of realising an accurate probabilistic framework for uncertainty quantification. Through using the predicted variance, we adapt the feedback gains as more accurate models are learned, leading to low-gain control without compromising tracking accuracy. Using simulated and real data recorded from a seven degree-of-freedom robotic manipulator, we illustrate how using stochastic variational inference with deep kernel models increases compliance in the computed torque controller, and retains tracking accuracy. We empirically show how our model outperforms current state-of-the-art methods with prediction uncertainty for online inverse dynamics model learning, and solidify its adaptation and generalisation capabilities across different setups.