Robotic Rehabilitation

Cerebral Palsy affects over 50,000 Canadians and upwards of 17 million people worldwide. The disease presents in early childhood and affects muscle tone, movement and motor skills. There are rehabilitation treatments to help manage symptoms, but as University of Waterloo engineering alum, Manmeet Maggu, realized after finding out his nephew, Praneit, was diagnosed with the disease, there are limitations to traditional treatment methods.

“That’s when we decided to build something for my nephew,” Maggu explains. “We also saw that there are so many children out there with similar disabilities who could benefit from some sort of device to help their walking and rehabilitation.”

While at the University of Waterloo, Maggu partnered on the endeavor with fellow engineering undergrad Rahul Udasi as a fourth year Mechatronic Engineering project.

In the process, the duo discovered promising research in the area of robotic rehabilitation but early investigations revealed few options on the market – primarily exoskeletons designed to assist adults with mobility issues. These devices were bulky and expensive, making them inaccessible for most children. It was at this point that they decided to launch their own company, Trexo Robotics, to design a pediatric exoskeleton for robotic rehabilitation.

“Over the years, the project has been evolving with many different prototypes to improve the design,” Maggu explains.

When it comes to designing an exoskeleton, two major concerns came into play – safety and weight-bearing ability. Maggu explains that although there are adult exoskeletons available, they require a certain upper body strength and cognitive ability to operate, rendering them ineffective for their purposes.

“Because we were designing this for children, we decided to design around an outer frame and an exoskeleton device inside that frame,” Maggu explains. “That way, with this device, the child can never fall and there is maximum support provided.” The outer frame is similar to a walker with wheels that stabilizes the child while the exoskeleton is affixed to the body to help with mobility and rehabilitation techniques.

The team’s focus has shifted from developing a device that works at the most basic level to designing a sophisticated product that can improve the lives of those requiring it. In the early stages of development, Maggu and Udasi traveled to India to allow Maggu’s nephew to test out the device. They were able to get positive real-time feedback from Praneit as well as his parents and physiotherapists about the benefits of using such a device.

This particular exoskeleton, dubbed Trexo, was designed with robotic rehabilitation in mind and can help a child’s gait, posture and overall balance.

Along the way, the team encountered some design challenges though, including deciding on the best actuator technology.

“In our case, space was a big constraint, we weren’t only designing an exoskeleton that needed to be small and mobile but also it was an exoskeleton for children, so making sure that everything is compact was a big design challenging,” says Maggu. “Not only keeping the actuators small and compact but at the same time keeping them big enough so that they could handle the different range of weights that we can expect a child to have.”

The device includes its own control system with a proprietary control algorithm that can detect the forces a child is applying and takes these into account to generate a gait pattern for the child to operate within.

“We have our own micro controller and computer board on the device,” Maggu adds. “We also have additional smaller computer units doing smaller things like getting encoder data and preparing the data for the main computer to do the computing. We have internal PID loops/internal control loops for each joint and a master algorithm providing the higher level gait patterns.”

The device itself was designed with a combination of material. Stainless steel is used throughout the exoskeleton at maximum stress points. Maggu explains that they also used a lot of 3D printed parts as plastic is light and inexpensive and in many cases ideal for mobile devices.

“3D printing has made production much easier for us, otherwise we would have to pay thousands of dollars to have molds made,” explains Maggu. “Now, we can get 3D printed parts instead. As we ramp up production, we will obviously move into injection-molded parts. However, 3D printing has really enabled startups to make it possible to develop part for their products.”

Getting everything to work together seamlessly has been a challenge, but one that both Maggu and Udasi have overcome. Trexo Robotics is pushing the limits of robotic rehabilitation to improve the lives of children living with disabilities.

“This is a natural evolution for us,” Maggu explains. “Needing up to three physiotherapists to do the same motion that a robotic device can do, developing a robotic exoskeleton seems like the sensible path to go forward.  Physiotherapists can now have these robotic devices at their disposal to provide better care to these children. By making them more accessible and more affordable, we are enabling both physiotherapists and children to enable better care overall.”

The duo is currently working on their fifth iteration of the device, ensuring that the device is highly adjustable, while also focusing on the commercial applications of the exoskeleton. Every point requires a level of adjustability to enable children of all sizes and skill level to be able to operate within it. They are also working on the mobility aspects, making sure the device can fit through regular doors and that it is light and easy to transport.

Maggu believes Trexo is at the cutting edge of robotic rehabilitation technology. The company has had some commercial success, having spoken with several clinics in Ontario. For example, London, ON-based Able Bionics, a distributor of exoskeleton devices, has agreed to purchase the first Trexo device.

Going forward, the two hope to broaden their range of support devices with different sizes and versions. With this expanded product range, Maggu expects the company to grow with it, and the duo are always on the lookout for like-minded people to join them in the cause.

“Our philosophy is to explore the leading research regarding different topics and incorporate that to build something that is as advanced as it can be,” Maggu says.

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