Team : Luminous

Name	USN	Semester
Vishal	U25UV24T043121	3rd Sem
Parthjit Singh	U25UV24T043076	3rd Sem
Khusi mittal	U25UV23T040045	5th Sem
Arpit Maurya	U25UV24T040017	3rd Sem

InMoov Humanoid Hand & Forearm — Explanation

1. Introduction

The InMoov hand and forearm is an open-source, 3D-printed robotic limb designed by Gaël Langevin.
It is widely used in robotics research, education, and prototyping because all parts, instructions, and codes are free and customizable.

This design uses tendon-driven mechanics, servo motors, and modular 3D-printed components to replicate the basic movement of a human hand and wrist.

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2. Major Components

2.1 3D-Printed Parts

The assembly consists of several printed parts including:

• Five fingers (thumb, index, middle, ring, pinky)
• Wrist components (rotational and tilt)
• Forearm shells
• Gear mechanisms
• Servo brackets and cable guides
• Covers and structural supports

Each part is printed separately and then assembled using screws, glue, and bolts.

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3. Working Principle

3.1 Tendon-Driven Mechanism

The fingers of the InMoov hand move using nylon fishing lines that act like tendons.
When a servo rotates, it pulls the tendon, causing the finger to bend.
When the servo releases, the finger returns to its open position, assisted by:

• Elastic tension
• Mechanical design of joints

3.2 Servo Motors

Each finger has one or more servos for actuation.
Servos are placed inside the forearm and connected to the tendons.

Servo functions:

• Pull tendons to close the fingers
• Release tendons to open fingers
• Rotate and tilt the wrist using gear-driven servos

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4. Electronics and Control

4.1 Microcontroller

The system typically uses:

• Arduino Mega
• Arduino Uno (for smaller setups)

4.2 Power Supply

A dedicated 5V–6V external supply is recommended due to high servo current draw.

4.3 Programming

Servos are controlled through PWM signals generated by the microcontroller.

A basic Arduino program includes:

• Attaching servos to pins
• Setting initial (zero) positions
• Moving servos to given angles
• Creating finger sequences like open/close motions

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5. Assembly Overview

5.1 Printing

Parts must be printed with:

• 20–30% infill
• Good dimensional accuracy
• Minimal warping (calibrator is provided for accuracy)

5.2 Mechanical Assembly

The steps include:

1. Printing all finger and wrist parts
2. Aligning and gluing/screwing joints
3. Installing servos
4. Routing tendons through Teflon tubes
5. Adjusting tension using tensioners
6. Installing wrist rotation and gear system

5.3 Calibration

• Each servo is set to 90° neutral position before attaching tendons
• Tendon tightness is adjusted so that fingers stay straight at neutral
• Movements are tested with small angle increments

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6. Applications

The InMoov hand is used in:

• Robotics education
• Humanoid research
• Prosthetic experiments
• Animatronics
• DIY and maker projects

Its open-source nature allows users to modify, redesign, and improve the system freely.

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7. Advantages

• Fully open-source
• Affordable & 3D-printable
• Highly customizable
• Realistic tendon-based motion
• Large community support

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8. Limitations

• Requires precise 3D printing
• Tendons can wear over time
• Servos generate heat and require sufficient power
• Assembly is complex for beginners

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9. Conclusion

The InMoov humanoid hand and forearm represents one of the best open-source robotic hand systems available today.
Its realistic motion, modular design, and accessible components make it a valuable tool for learning and experimenting with robotics, mechanical engineering, and human-like motion systems.
click here to view video of performance