Through the fusion of robotics and textiles, the team developed a wearable garment which acts as an extension of the human body and has been specifically designed to assist adults who have reduced mobility with everyday activities including carrying, standing up, walking, hiking and more. The suit is based on Twisted String Actuator technology and was originally developed at the Stanford Research Institute (SRI) as part of a Defence Advanced Research Projects Agency (DARPA) research program to reduce the risk of injury and enhance the endurance of soldiers. However, having realised its potential commercial value, our customer established their own apparel brand and began to explore the fusion of robotics and clothing across a wide range of textile applications.
The suit is neither an exoskeleton nor a medical device. It is a sophisticated robotic undergarment that augments the wearer’s core and hip strength to improve mobility. Our customer challenged PCH to engineer a commercially viable product based on the company’s existing proof-of-concept prototypes, which were too expensive, noisy, and bulky for mass adoption.
The biomechanics of the product were particularly challenging because the forces applied by the suit’s battery-powered and motor-driven “FlexDrives” to the body differed depending on the location of the drives relative to the wearer’s joint locations, and on the wearers body shape and size. Additionally, the PCH team was tasked with reconciling the product’s sleek industrial design vision with the volume of the components required to power the suit. The weight, bulk, and noise that was acceptable in the original military design needed to be reduced in order to engage in user testing and consumer research with PCH’s prototype. The apparel aspects of the product would also have to be completely reimagined to allow for easy donning and doffing particularly as the product’s target audience suffers from reduced mobility, balance, and agility. Lastly, the overall cost of the suit would need to be reduced to fit with the customer’s business model.
Our customer had already collaborated with Shima Seiki, a 3D knitted garment producer, to create the seamless base layer for the suit. To build on this, PCH worked closely with fuse-project, an industrial design firm based in San Francisco, to deliver a ‘works-like, looks-like’ prototype. PCH’s mechanical, electronic, firmware and soft-goods engineers set out to engineer a smaller, more powerful suit that could be discretely worn underneath the user’s street clothes.
Working closely with fuseproject, PCH selected an optimized motor and determined the placement of the FlexDrive modules on the body and developed custom contoured battery pack assemblies to house the battery cells and reduce the bulkiness of the suit. PCH’s soft-goods engineers partnered with our customer’s world-class apparel design team to scrutinize every mechanical feature and fastener on the product with the goal of blending the hard-goods into the soft apparel layer of the suit.
When developing the system architecture for the suit, PCH evaluated various communication topologies, eventually implementing a CAN bus architecture (a high-speed, high-band-width communication protocol that is common in the automotive industry). Through the use of multiple inertial measurement sensors, the activation of the FlexDrives across the body was synchronized for precise timing with body movements.
Optimizing the human-factors of comfort, wearability, mobility, donning and doffing and toileting were critical to the success of this project. Over the course of 11 months of intense in-person collaboration, PCH delivered a functional battery-powered and motor-driven commercially viable prototype that reduced the bulkiness, weight and audible sound of the original suit and could be worn under street clothing.
Along the way, PCH designed a new scalable electrical architecture and communication protocol, and optimized the FlexDrive design for high power, low cost, and improved manufacturability. Utilizing PCH’s deep supply chain expertise, the team was also able to deliver a fully customized force sensor that was instrumental to the suit’s onboard control system. Since delivery of the PCH prototypes our customer began running a beta program in partnership with an elderly care community based in Seattle.