Planar Snake Robot with Game Theory Control

A 4-link planar snake robot simulation in Simscape Multibody, controlled using a PD controller for lateral undulation locomotion.

Overview

This project demonstrates:

• Multi-body dynamics modeling in Simscape Multibody
• Control for underactuated systems
• Contact dynamics and friction modeling for snake locomotion
• CAD integration with Simulink

Features

• 4-link serial chain with 3 actuated revolute joints
• Planar motion constraint (X-Y plane)
• Ground contact forces with stick-slip friction model
• PD controller for coordinated joint actuation
• Real-time visualization in Mechanics Explorer

Demo

Requirements

• MATLAB R2024a or later (adjust based on your version)
• Simscape Multibody toolbox
• Simulink

Installation

1. Clone this repository:

   git clone https://github.com/YOUR_USERNAME/snake-robot-control.git
   cd snake-robot-control

2. Open MATLAB and navigate to the project directory.
3. Run the model (for example, open the Simulink model file and press Run).

Model Structure

Physical System Links: 4 identical segments (mass: 0.042 kg each) Joints: 3 revolute joints (Z-axis rotation) Base: Planar joint (X-Y translation + Z rotation) Ground contact: Spatial contact forces on each link

Control Architecture

Input: Joint angles and velocities (θ₁, θ₂, θ₃, ω₁, ω₂, ω₃) Output: Joint torques (τ₁, τ₂, τ₃)

Key Parameters

% Link properties
link_mass = 0.042;              % kg
link_length = 0.072;            % m (2 × 0.036)

% Contact parameters
friction_static = 1.2;
friction_dynamic = 0.8;
stiffness = 1e6;                % N/m
damping = 1e3;                  % N/(m/s)

% Control parameters
amplitude = 0.5;                % rad
frequency = 1.0;                % Hz
phase_shift = pi/3;             % rad

Results

The snake robot successfully exhibits:

• Lateral undulation gait
• Forward locomotion on flat terrain
• Stable planar motion (no out-of-plane deviation)
• Smooth joint trajectories

Project Background

This project was developed to demonstrate:

Multi-body system modelling capabilities in Simscape Multibody Advanced control theory implementation CAD integration with simulation tools

CAD Model Credits

The link geometry (TEST_SNAKE_BRACKET) is from: CAD file

License

This project is licensed under the MIT License - see the LICENSE file for details.

Author

Maria Luisa Scarpa PhD in Control Theory (Dynamical Systems, Optimal Control, Game Theory) Background: Aeronautical Engineering LinkedIn: My profile Email: [scarpa.mari@gmail.com/ mls18@ic.ac.uk]

Acknowledgments

CAD model from CAD file Simscape Multibody documentation and examples