This repository contains source code associated with the paper "Concerted Control: Modulating Joint Stiffness Using GRF for Gait Generation at Different Speeds" by Shunsuke Koseki, Omid Mohseni, Dai Owaki, Mitsuhiro Hayashibe, Andre Seyfarth, and Maziar A. Sharbafi.

The code simulates a bipedal model using the MuJoCo physics engine, representing a human with a height of 180cm and a weight of 80kg. The model's movement is constrained to the sagittal plane and includes seven degrees of freedom: one torso joint (between the pelvis and the torso), two hip joints, two knee joints, and two ankle joints.

The controller implemented in the model is a bioinspired, simple, and easy-to-implement walking controller, termed Concerted Control. This controller leverages a shared common signal to coordinate movements across multiple joints without relying on predefined trajectories. It builds on our previously developed Force Modulated Compliance (FMC) control concept, which modulates joint stiffness based on ground reaction forces (GRF). In Concerted Control, FMC is applied across multiple joints, enabling implicit coordination through the shared GRF signal, without the need for a centralized controller.

We evaluated the performance of Concerted Control on the simulated bipedal walker and demonstrated that it can generate stable walking gaits across a wide range of speeds, from 0.7 to 1.8m/s. Additionally, robustness was assessed through external angular momentum perturbation tests, which showed the gaits to be robust. By replicating key kinematic and kinetic characteristics of human walking, Concerted Control offers a promising framework for enhancing the control of mobile robots and assistive systems.