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  • Building a Better Wheelchair for Car Drivers

Photonics Spectra
Feb 2007
Hank Hogan

Powered wheelchairs both help and hinder users. Over short distances, the conveyances help people get around. However, for longer distances, where one typically would use a car, wheelchairs get in the way. Storing them safely for a trip is difficult — often requiring an assistant — and entails extensive and costly vehicle modification.

Now a group of engineers from Carnegie Mellon University in Pittsburgh, Lehigh University in Bethlehem and Freedom Sciences LLC of Philadelphia, all in Pennsylvania, has devised a system that combines robotics, lasers and wireless technologies to enable a wheelchair to automatically stow itself in a secure fashion.

John Spletzer, assistant professor of computer science and engineering at Lehigh, noted that the laser rangefinders employed in the system are not groundbreaking. “We are using a commercial, off-the-shelf lidar system.”

It is actually the same lidar, made by Sick Inc. of Minneapolis, that was used by the winner of an autonomous robot race sponsored by the US Department of Defense. For the wheelchair docking application, the lidar provides both range and relative reflectivity data for each bearing measurement.

The latter information is important because the wheelchair must be maneuvered without human intervention into very tight quarters: The clearance between a chair’s wheels and the rails of the lift platform is as little as 4 cm. Once the wheelchair is equipped with two small retroreflectors, the lidar provides the information needed for this tricky navigation.

In operation, the user transfers into a seat in the vehicle and then drives the wheelchair by remote control until it gets close enough to the lidar, which is integrated into the lift gate at the rear of the vehicle. From there, the apparatus — dubbed the Automated Transport and Retrieval System — takes over, driving the wheelchair onto the lift and stowing it in the vehicle.

In the original proof-of-concept design, the functions were performed using a machine vision system. However, the engineers switched to lidar to make the wheelchair transport and retrieval system more robust in varying conditions, noted Tom Panzarella, chief technology officer of Freedom Sciences. The company is in the process of commercializing the technology, with testing at beta sites already under way.

Panzarella reported generally positive feedback from potential end users, and the company is working to address any concerns that are raised. He also noted that the technologies involved in the product might not be state-of-the-art but the combination is. “This could be one of the first real uses of outdoor mobile robotics for people in the commercial space ever,” he said.

Contact: John Spletzer, Lehigh University; +1 (610) 758-5783; e-mail: Tom Panzarella, Freedom Sciences LLC; +1 (215) 467-4270; e-mail:

The technology of generating and harnessing light and other forms of radiant energy whose quantum unit is the photon. The science includes light emission, transmission, deflection, amplification and detection by optical components and instruments, lasers and other light sources, fiber optics, electro-optical instrumentation, related hardware and electronics, and sophisticated systems. The range of applications of photonics extends from energy generation to detection to communications and...
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