✋ Hand Rehabilitation using Soft Robotics

Undergraduate Thesis

Vishwakarma Institue of Technology

Pune, India

Sep. 2022– Dec. 2022

🎯 Objective

Design and develop a soft robotic glove capable of assisting hand rehabilitation exercises through pneumatically actuated PneuNet bending actuators. The goal was to replicate natural finger motion safely and affordably, enabling patients to perform self-guided physical therapy with minimal therapist supervision.

Cross-sectional view of the fiber-reinforced soft pneumatic actuator enabling controlled bending for finger rehabilitation.

Conceptual demonstration of the hand’s open-to-close motion used in repetitive rehabilitation therapy.

💡 Motivation

Traditional robotic rehabilitation systems often rely on rigid actuation and expensive clinical hardware, making therapy cumbersome and inaccessible. Soft pneumatic actuators (SPAs) offer an inherently safe, compliant, and low-cost alternative that can adapt to the human hand’s natural movement.

This project was motivated by the need for affordable, wearable, and patient-friendly rehabilitation devices to help individuals regain motor control after injury or stroke.

⚙️ Approach

1️⃣ Actuator Design & Analysis

Designed PneuNet-based soft bending actuators for four fingers (excluding thumb).
Performed geometric analysis and FEA (Abaqus) using the Yeoh hyperelastic model to predict bending curvature and tip force.
Optimized wall thickness, chamber height, and spacing to achieve 270° bending at 55 kPa.

FEA simulation of PneuNet actuator bending curvature at 55 kPa input pressure.

2️⃣ Fabrication

Created two-part 3D-printed molds (PLA, 0.2 mm layer) for casting Ecoflex 00-30 silicone actuators.
Embedded a paper-reinforced inextensible layer for strain limitation and controlled curling.
Fabricated four actuators matching finger lengths (112–142 mm).

3D-printed molds and fabricated soft actuators for four fingers.

3️⃣ Fluid Control & Integration

Developed a Fluid Control Board (FCB) with:
- Dual mini air pumps,
- Solenoid valves,
- Pressure sensor,
- Arduino UNO with PWM control.
Enabled manual and automated control for inflation/deflation cycles.
Integrated flex sensor feedback for real-time motion tracking.

Pneumatic control board with Arduino-based actuation system.

4️⃣ Testing & Characterization

Clamped actuators for controlled displacement tests.
Validated actuator curvature and response vs. FEA predictions.
Demonstrated synchronized finger flexion using multi-actuator tests.

Fabricated soft pneumatic actuators enabling finger flexion for hand rehabilitation exercises.

Enter system overview

📈 Results

Actuators achieved > 270° bending at < 60 kPa, matching FEM simulations.
Demonstrated safe, repeatable finger motion suitable for rehabilitation exercises.
Fabricated prototype produced consistent bending with low hysteresis and fast recovery (< 0.5 s).
Validated feasibility of low-cost wearable pneumatic devices for home-based therapy.

Actuation of a finger setup showing progressive curling during inflation.

Actuation of multi-finger setup showing progressive curling during inflation.

🌍 Impact

This project demonstrates the potential of soft pneumatic actuation for assistive rehabilitation. By combining compliant materials, rapid prototyping, and modular control, the device provides a foundation for:

Affordable self-rehabilitation systems for stroke or injury recovery.
Integrating biosensors (heart-rate, SpO₂) for closed-loop therapy monitoring.
Future clinical translation through wearable glove integration and adaptive control.