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Design and Evaluation of a Distributed, Shared Control, Navigation Assistance System for Power Wheelchairs

Sharma, Vinod Kumar (2011) Design and Evaluation of a Distributed, Shared Control, Navigation Assistance System for Power Wheelchairs. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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A significant number of individuals with disabilities are denied powered mobility because they lack the visual, motor, or cognitive skills required to operate a powered wheelchair safely. The Drive-Safe System (DSS) is an add-on, distributed, shared control navigation assistance system for powered wheelchairs, intended to provide safe and independent mobility to these individuals. The DSS is a human-machine system in which the user and machine share navigation control. The user is responsible for high-level control of the system, such as choosing the destination, path planning, and some navigation actions, while the DSS overrides unsafe maneuvers through autonomous collision avoidance, automatic wall following, and door crossing. This dissertation reports the design and development of the DSS, followed by results from rigorous engineering and clinical evaluations. The engineering tested technical aspects of the DSS such as sensor coverage, maximum safe speed, maximum detection distance, and power consumption. Clinical evaluations included testing the DSS with Orientation & Mobility (O&M) specialists, ambulatory and non-ambulatory visually impaired individuals, and able-bodied controls. We compared the performance of the DSS with conventional navigation aids such as canes that are commonly used in conjunction with wheelchairs based on measures such as time for task completion and number of collisions. Additionally, we collected data with the NASA-TLX to gain insight into users' subjective experience with the DSS. Results indicate that the DSS was able to provide a uniform and reliable sensor coverage field around the wheelchair and could successfully detect obstacles as small as 3 inches in height to overhanging obstacles at a height of 55 inches. The DSS significantly reduced the number of collisions compared to using a cane. Users rated the DSS favorably despite the fact they took longer to navigate the same obstacle course than they would using a cane. Visually impaired participants reported experiencing less physical demand, and had to exert less effort in order to achieve better performance when using the DSS, compared to using a cane. These findings suggest that the DSS can be a viable solution for powered mobility in populations with visual impairment.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Sharma, Vinod
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairSimpson, Richard Cris20@pitt.eduRIS20
Committee MemberDing, Dandad5@pitt.eduDAD5
Committee MemberLoPresti, Edmund
Committee MemberSchmeler, Markschmeler@pitt.eduSCHMELER
Committee MemberCooper, Rory Arcooper@pitt.eduRCOOPER
Date: 11 July 2011
Date Type: Completion
Defense Date: 2 July 2009
Approval Date: 11 July 2011
Submission Date: 17 July 2009
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Bioengineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Embedded Distributed; Navigation Assistance System; Power Wheelchairs; Shared Control; Smart wheelchair
Other ID:, etd-07172009-103647
Date Deposited: 10 Nov 2011 19:51
Last Modified: 15 Nov 2016 13:46


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