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Power-Actuated Laptop Computer Tilter

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Contents

Situation

A student with spinal muscular atrophy rides a powered wheelchair and has very limited arm and hand function, with reach limited to approximately 10 inches out from his torso. He typically uses a laptop computer on his wheelchair laptray, using a modified mouse and onscreen keyboard for access.

The client received a new Permobil wheelchair with a joystick and control pad (for powered lift, recline, leg lift, etc.) embedded into the center of his laptray, where the laptop computer needed to sit. There was insufficient space to move the laptop beyond the control pad, and extending the tray would have blocked his view for maneuvering the wheelchair. As well, he needed a way to raise and lower the computer screen for computing or driving, respectively. Finally, he could not reach the computer's on/off switch. (A docking station that might allow alternate access to the on/off switch was not available.)


Accommodation

With design input from Ronny Gaal, I devised a tiliting base for the laptop computer, which was mounted to the front edge of the laptray using a modified DaeSSy mounting system. The laptop was placed as close to the user as feasible. I utilized a linear actuator, powered by the wheelchair's batteries, to tilt the laptop base up approximate 40 degrees. This enabled the user to reach the wheelchair controls underneath. A second actuator was used to lift and lower the laptop screen to the desired angle. Both actions were controlled by double-pole double-throw switches with extended lever arms placed within user�s reach range. Finally, a mechanical arm was connected to the screen lifting mechanism to rotate down and depress the on/off button as the lid was raised past 90 degrees (vertical).


Cost Analysis

As with any one-time device of this complexity, the real-time cost significantly exceeded the authorized fee of $2000.


Repeatability of Solution

This device had to be custom fit for the particular laptop. While the basic concept has been proven and other similar models can be designed more readily, additional design work would be needed for each device.


Acknowledgements

Ray Grott, MA, ATP

Rehabilitation Engineering & Technology Project

San Francisco State University

www.retproject.org

415-338-1333

rgrott@sfsu.edu


[1] http://www.workrerc.gatech.edu