Design of a Load Sharing Sit-to-Stand Assistive Test Bed
By Jeyasurya, J.; Lai, T.; Patil, O.; Pospisil, E.; Van der Loos, H.F.M.; Croft, E.A.; Hodgson, A.; RESNA/ICTA 2011: Advancing Rehabilitation Technologies for an Aging Society, June 5-8, 2011, Toronto, Canada,Publication Date: 2011
Paper describes the design of a Load-Sharing Sit-to-Stand (STS) Assistive Test Bed for independent transfer. The stated purpose of the test bed is to assess the trajectory, stability, and load sharing produced by different STS assist mechanisms. Results from these assessments will help characterize the biomechanics of assisted STS transfers and provide guidance in the development of new devices. The following assist mechanisms are included in the design: (1) an arm assist consisting of dual 4-bar mechanisms that guide the user’s elbows through a specified STS trajectory; (2) a waist assist mechanism representative of many institutional lists, which uses a U shaped lever arm rotating about a pivot in front of the user and providing assistance through a pair of straps attached between the ends of the U and a padded transfer harness at the vest; and (3) a buttocks assist mechanism representative of chair mounted lifting aids, which utilizes a hinged seat on a lever arm rotating about a pivot under the user’s knees; as the lever arm rotates, the seat provides a forward and upward force to assist the user to a standing position. The test bed is actuated by a quarter-horsepower direct-current parallel shaft gear motor coupled to a cable driven mechanism for the buttocks and waist assists, and to a gear and linkage mechanism for the arm assist. Sensors are added to capture the kinematics and dynamics of the user’s STS motion. Preliminary experiments with the test bed showed that all of the methods of assist increased the stability of the user. Directions for future development of the test bed are discussed.
Published by: Rehabilitation Engineering & Assistive Technology Society of North America (RESNA) (Website:http://www.resna.org)
Rehabilitation Engineering & Assistive Technology Society of North America (RESNA) (Web Site: http://www.resna.org )
Link to text: http://web.resna.org/conference/proceedings/2011/RESNA_ICTA/jeyasurya-69770.pdf
