Accessibility in an Autonomous Future

Abstract/Contents

Abstract

Level 5 advanced autonomous vehicles could be available for use as soon as 2030, allowing vehicles to drive anywhere without drivers. In this impending future, driverless vehicles may exclude people who use manual wheelchairs, of which there are currently 2.7 million in the U.S. alone. Current forms of wheelchair transportation often require aid from the driver to help the individual into the vehicle and be secured. Our team has developed a system to allow people in wheelchairs to enter an autonomous vehicle, secure themselves, and exit the vehicle without additional assistance. Our prototype to facilitate entry and exit into the vehicle is a deployable ramp which uses a modified four-bar system to allow for concealment within the floor of the vehicle as well as full deployment to the ground. Our prototype to achieve securement uses two outward-facing spring-loaded teeth to secure the wheelchair by the vertical components of its frame, using only the motion of the wheelchair for actuation. After the ramp deploys, the user will be able to wheel themselves up it and into the vehicle, where they can then back into the securement mechanism and lock into place. Then, a pull handle allows for mechanical release from the securement. The ramp is currently able to be moved manually along its intended motion path, however the eventual system would actuate automatically via motors on each arm. Upon testing the deflection of the ramp, it was able to withstand 900 pounds of weight as required by the ADA, and keep the maximum deflection of the ramp under 1.5mm. In order to test the securement mechanism, we scaled down the required forces and applied them to a 3D-printed version of the mechanism. Using the ratio of the yield strengths of PLA and aluminum 6061, we calculated these forces to be 264 N of lateral force and 160 N of axial force, which were numbers calculated from accelerations and turns associated with strenuous driving conditions. Upon testing we found that our mechanism successfully withstood these forces without yielding. Using the full-scale securement prototype, we were able to allow for 8 first-time users to secure themselves in under 40 seconds with times ranging from 14 to 38 seconds. Actuating the release for the securement mechanism took 10 pounds of force, exceeding our requirement of 5 pounds or less, and is currently inaccessible by the user while secured. Our tests concluded that with the exception of the securement release actuation, both mechanisms meet ADA requirements and are capable of allowing a user to enter, secure within, and exit a vehicle. Future steps include connecting the ramp to motors, extending the securement release mechanism to be accessible by the user, and reducing the force needed to release the securement.

Description

Type of resource	text
Publication date	April 3, 2023; 2023

Creators/Contributors

Author	Robertson, Timothy
Author	Bernardo, Jack
Author	Briones, Brandon
Author	Athanasopoulos Yogo, Telis
Advisor	Wood, Jeff
Advisor	Marable, Melissa
Advisor	Suen, Oscar

Subjects

Subject	Accessible Design
Subject	Mechanical engineering
Genre	Text
Genre	Report

Bibliographic information

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DOI	https://doi.org/10.25740/qw824kr4672
Location	https://purl.stanford.edu/qw824kr4672

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Preferred citation

Robertson, T., Bernardo, J., Briones, B., and Athanasopoulos Yogo, T. (2023). Accessibility in an Autonomous Future. Stanford Digital Repository. Available at https://purl.stanford.edu/qw824kr4672. https://doi.org/10.25740/qw824kr4672.

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ME170 Mechanical Engineering Design

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