Overview

We extended a repetitive control method based on the "virtual trajectory" — the time series of spring equilibrium positions — to physical robotic joints with antagonistic muscle structures like the human body. Combined with variable stiffness mechanisms, an accurate virtual trajectory can be acquired in a small number of repetitions while keeping the joint compliant.

Technical Features

• Model-free control based on the virtual trajectory (time series of spring equilibrium positions)
• Combination with repetitive control achieves both compliance and accuracy
• Demonstrated on physical antagonistic and variable-stiffness joints

Specifications

• Control law: virtual-trajectory-based repetitive control
• Targets: antagonistic-muscle robotic joints and variable stiffness mechanisms
• Feature: accurate trajectory tracking while keeping the joint compliant