Pediatric Robotic Lower Limb Exoskeleton

What it does

Project develops a Paediatric Robotic Lower-Limb Exoskeleton with an intelligent controller for personalized gait planning. It addresses the mobility and rehab needs of children with neurological disorders, enhancing their independence and quality of life.

Your inspiration

My motivation for this project stems from a strong desire to improve the quality of life for children like my best friend’s 8-year-old daughter, Rose Firouzbakhsh, a spastic Cerebral Palsy patient at Gross Motor Function Classification System (GMFCS) Level IV, indicating severe mobility disorders. The idea for the exoskeleton solution emerged from an advertised PhD project that I found both interesting and applicable. After being admitted to the program and completing my PhD, I established my company, BionicEXO Ltd (registration number 14983746), to further develop this assistive technology and make a positive impact on children's lives.

How it works

My design is a wearable PRLLE tailored for children with severe mobility disorders. The exoskeleton is worn on the legs and hips, supporting and enhancing movement. It features an intelligent controller with advanced sensors and algorithms to adapt to the child's unique gait pattern. These sensors detect the child's movements and send data to the controller, which activates motors to adjust the exoskeleton's joints in real-time. The technology includes adaptive central pattern generators (ACPGs) that synchronize joint movements, ensuring smooth and natural motion. A reinforcement learning (RL) agent learns the dynamics of the child's movements to optimize physical Human-Robot Interaction (pHRI) and the level of assistance. The exoskeleton is lightweight, adjustable, and designed to grow with the child, making it a practical solution for long-term use. By enhancing mobility, this technology aims to improve the child's independence and quality of life.

Design process

Pre-design: An anthropometric study ensured the exoskeleton fits children aged 8 to 12. Dimensions for height, leg length, and foot size were analysed for the 50th percentile. Gait analyses on 31 children aged 8-12 determined torque, power, and velocity at the joints. A 24V brushless Maxon motor and strain wave gearing were selected. Maxon EPOS4 controllers, supporting EtherCAT protocol, were chosen for motor control. Design: Using derived dimensions and selected components, the first CAD design of the PRLLE was created in SolidWorks. The right leg was designed first, then mirrored for the left. The CAD files from suppliers for Maxon Motors, EPOS4 drivers, and HarmonicDrive gearboxes were used. Prototyping: Initially, I used aluminum tubes and 3D-printed connectors. Testing revealed knee motor housing instability. These issues were addressed by redesigning the PRLLE with CNC-machined connectors. The first prototype had six actuated joints: 4 at the hip and 2 at the knees. Due to weight, the Hip Abduction/Adduction motors were removed, resulting in the second prototype with four motorized joints. The exoskeleton was refined with sensors, including hall sensors, encoders, pressure sensors, IMUs, and a Speedgoat real-time target machine as the master EtherCAT.

How it is different

My design stands out from existing PRLLEs like ATLAS 2030 (Marsi-Bionics, Madrid, Spain) and Trexo Plus (Tréxō Robotics, ON, Canada) in several ways. The ATLAS 2030, priced at €180,000, is financially prohibitive, and the Trexo Plus, only available in Canada, has a long waitlist. Both devices rely on predefined fixed gait trajectories, which don't accommodate the unique gait patterns of children with neurological disorders. This becomes a major issue as fatigue sets in, affecting step length and gait speed, and leading to deviations. Our PRLLE addresses these challenges with an intelligent controller that adapts to each child's unique gait in real-time. This ensures a personalized fit, enhancing mobility and reducing fatigue. Additionally, our design is more affordable and accessible, aiming to remove financial and geographic barriers. By focusing on adaptability and customization, our PRLLE offers a significant improvement in user experience and effectiveness.

Future plans

The next steps involve refining the PRLLE prototype through iterative testing. I will integrate advanced sensor technology and enhance the intelligent controller for better adaptability to each child's unique gait. Additionally, I plan to conduct clinical trials with healthy and CP patients to validate the device's efficacy and safety after receiving electrical and magnetic certifications. Following successful trials, I will pursue regulatory approval for compliance with medical device standards. My goal is to make the PRLLE widely accessible, improving mobility and quality of life for children with mobility disorders globally via BionicExo.

Awards

I have been awarded the esteemed Hudswell International Research Scholarship (£5,000), one of the most challenging and prestigious IET Postgraduate Research Awards for 2023. More information below: https://www.theiet.org/impact-society/awards-prizes-and-scholarships/iet-postgraduate-research-awards/2023-winners