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Soft mechanism driven Robots for Rescue OPS & Landmine Clearance

Idea Proposed

Image

Fig. 1 | Framework extending classical mechanism design to soft robotics. A Design process. Inspired by nature, we observe the walking trajectories of quadrupeds such as horses. We then select a trajectory from a four-bar atlas. We synthesize the corresponding linkage in the ideal design domain. Finally, we convert the linkage into a multi-material design by replacing ideal joints and links with variations of soft and hard materials. b Application. We assemble the printed parts and integrate the electronics into the robot body, creating a soft mechanism driven robot.



A soft-hybrid quadruped robot that:

  • Uses multi-material 3D printing to blend soft and rigid materials.
  • Achieves efficient walking using four-bar linkages instead of traditional pneumatic actuation.
  • Can traverse different terrains, including sand, soil, and rocks.
  • Has impact resistance, withstanding high forces while maintaining flexibility.
  • Uses low-cost thermoplastic polyurethanes (TPU) of different hardness levels.
  • Includes closed-loop control with encoders and microcontrollers for precise movement.

How These Robots Work

1. Soft-Hybrid Design

  • The quadruped robot’s legs are designed using a four-bar mechanism, allowing efficient movement similar to biological walking.
  • Soft joints provide impact resistance, while rigid links ensure structural integrity.
  • Different TPU materials (Shore hardness: 75D, 95A, and 85A) are used to fine-tune flexibility.

2. Actuation and Locomotion

  • Uses DC motors with rotary actuators instead of pneumatic actuators.
  • The four-bar linkage moves in a closed-curve trajectory, reducing friction and improving energy efficiency.
  • The robot’s body oscillates, mimicking animal movement for better stability.

3. Electronics and Control System

  • Quadrature encoders provide real-time feedback on motor rotation.
  • A custom PCB integrates power and communication for closed-loop control.
  • Uses a microcontroller (potentially ESP32 or STM32) for motor control and trajectory adjustments.

How to Build These Robots

1. Materials & Components

  • Multi-material 3D Printer (FDM with a tool-changer for different TPU hardness levels).
  • Thermoplastic Polyurethanes (TPU) of varying hardness:
    • Soft joints (85A TPU).
    • Rigid links (75D TPU).
  • DC motors with rotary encoders.
  • Custom PCB for control.
  • Microcontroller (ESP32, STM32, or Arduino).

2. Fabrication Process

  1. 3D Print the Robot Body & Legs

    • Use multi-material FDM printing to create flexible joints and rigid links in a single print.
    • Ensure strong adhesion between different materials.

  2. Assemble the Leg Mechanism

    • Attach four-bar linkages to the DC motors.
    • Use dowel pins to connect the crank link to the leg mechanism.

  3. Install Electronics

    • Solder quadrature encoders to track motor movement.
    • Connect the DC motors to a microcontroller via an H-Bridge motor driver.

  4. Program Motion Control

    • Implement closed-loop control using PID algorithms.
    • Define walking gaits (trot, gallop, etc.) in the microcontroller.

How to Implement These Robots

1. Applications

  • Search and Rescue: Navigating through rubble and debris.
  • Agriculture: Inspecting crops in uneven terrain.
  • Space Exploration: Surviving harsh conditions with impact-resistant legs.
  • Medical Assistance: Safe interaction with humans due to soft materials.

2. Enhancements & Future Work

  • Flexible Electronics: Avoiding rigid PCBs to improve overall softness.
  • AI-based Adaptive Locomotion: Using cameras and sensors for terrain adaptation.
  • Wireless Communication: Controlling the robot remotely via Wi-Fi or Bluetooth.

Sources & citation

Aygül, C., Güven, C., Frunzi, S.A. et al. A framework for soft mechanism driven robots. Nat Commun 16, 1426 (2025). https://doi.org/10.1038/s41467-025-56025-3