Parker Hannifin Brings Robotic Exoskeleton to Life with Digital Manufacturing

It all started seven years ago when then Parker Hannifin CEO, Don Washkewicz, challenged his team with the question, “What’s the future of our company?”

This triggered a flurry of activity to chart out new territory and opportunities that would secure the company’s growth well into the future. The initiative eventually led the company to investigate how it could adapt its core competencies in motion and control technologies to develop wearable robotic devices in the prosthetics and orthotics space.

As it explored the opportunity further, Parker Hannifin connected with researchers at Vanderbilt University working to adapt robotics technology to help patients with lower limb paralysis increase mobility and regain the ability to walk. This led to the development of a wearable exoskeleton that consists of a brace worn on the hips and legs, and is powered by motors, batteries, and other electronics.

In 2012, Parker Hannifin and Vanderbilt reached an agreement to license the technology and soon after the company began working to commercialize a robotic exoskeleton called Indego. Dr. Ryan Farris was a coinventor in the development of the technology as part of his doctoral work at Vanderbilt, and Parker Hannifin brought him on as the technical lead for the business unit tasked with bringing Indego to market.

Searching for a Flexible Material and Manufacturing Solution

Early on during the project, Farris and his team at Parker Hannifin quickly found the time spent waiting for production quotes and final parts through the company’s traditional manufacturing suppliers too long to meet their aggressive development deadlines.

Farris knew that in a highly competitive marketplace, where every day of product development can make or break success, time is of a premium. This pursuit—to shorten design cycles and manufacture parts faster—led him to Protolabs for prototyping and end-use parts.

“We primarily use Protolabs to test new ideas,” Farris explained. “For instance, as we consider a potential design improvement, we want the ability to create parts and see how they perform as quickly as possible.”

The Indego is a robotic exoskeleton designed to help patients with lower limb paralysis walk again. During development, Parker Hannifin used Protolabs to quickly test design improvements.

One particular design challenge that required quick-turn parts was related to a component that serves as a light pipe for the device. This part transmits light from a small LED on an embedded circuit board out to the exterior so the user can see the device’s current status.

“This little indicator is particularly important because this is how the user—the paraplegic, the stroke patient, or whoever is using the system—knows what state they’re in, what mode they’re in, and what’s about to happen with the device,” said Farris.

The initial light pipe design was manufactured with a moulded transparent thermoplastic. After several testing cycles, it became apparent the material was too brittle to hold up to the rigors of daily use, since the system was designed to flex with the user’s movement. Farris also explained the light pipe was a part of a larger assembly, and the relative motion of the assembly did not cooperate well with the rigid plastic-like component.

Rapid Silicone Rubber Tooling Bridges Production Gap

Farris and his team reevaluated the material used for the light pipe component and decided to manufacture the part with liquid silicone rubber(LSR). A moulded LSR part would be able to naturally flex with the user’s motion and have the durability to last indefinitely. But the challenge was more than identifying the proper material. They also needed a cost-efficient moulding option that was optimized for this stage of product development since design was not yet finalised.

The robotic exoskeleton was still in the prototyping phase and FDA approvals were still pending, so a costly investment in traditional tooling was not ideal. Farris turned to Protolabs’ LSR moulding process to quickly manufacture several light pipe components so that he could test the new design and have the flexibility to iterate if necessary.

He notes that the key to accelerating the moulding process was Protolabs’ automated, interactive quoting system. He and his team will often upload parts for quotes in a few hours, then go through several iterations until it is within their targeted cost. This enabled a highly iterative design process while reducing development costs since it could all be digitally achieved through software and did not require manufacturing final parts.