反復機械学習による直列弾性アクチュエータの高精度軌道追従
Iterative Machine Learning for Precision Trajectory Tracking with Series Elastic Actuators
直列弾性アクチュエータを用いた2自由度ロボットアームに対し、複素ガウス過程回帰で局所線形モデルを推定しながらフィードフォワード指令を反復学習し、位置追従誤差を低減する手法を提案・実証した。
著者: Nathan Banka, W. Tony Piaskowy, Joseph Garbini, Santosh Devasia
分類: eess.SY, cs.LG, cs.RO, cs.SY
原文アブストラクト
When robots operate in unknown environments small errors in postions can lead to large variations in the contact forces, especially with typical high-impedance designs. This can potentially damage the surroundings and/or the robot. Series elastic actuators (SEAs) are a popular way to reduce the output impedance of a robotic arm to improve control authority over the force exerted on the environment. However this increased control over forces with lower impedance comes at the cost of lower positioning precision and bandwidth. This article examines the use of an iteratively-learned feedforward command to improve position tracking when using SEAs. Over each iteration, the output responses of the system to the quantized inputs are used to estimate a linearized local system models. These estimated models are obtained using a complex-valued Gaussian Process Regression (cGPR) technique and then, used to generate a new feedforward input command based on the previous iteration's error. This article illustrates this iterative machine learning (IML) technique for a two degree of freedom (2-DOF) robotic arm, and demonstrates successful convergence of the IML approach to reduce the tracking error.
