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INNOVATION FOR INDEPENDENCE
ISSUE 70 December 09/January 10 £6.95
Dora opens doors for chair users By Dominic Musgrave SCIENTISTS in America have developed a robotic arm to help wheelchair users open doors. The permanently mounted door-opening robotic arm (Dora) was brainchild of Erin Rapacki, and has the potential to increase a power wheelchair user’s accessibility to indoor spaces. In tests the gripper opened doors with 14 different handles in 85 per cent of tests involving pushing the door, and 65 per cent of pulling. Erin told Assistive Technologies that while creating the arm, which cost 2000 dollars, she kept in mind that wheelchair users are often unable to reach and turn handles. She added: “Wheelchair-mounted robot arms are typically designed with many degrees of freedom to provide users with a general-purpose device for manipulating many of the objects necessary for activities of daily living. I considered a variety of designs of door knobs and handles that a door-opening robot must be able to grasp, and calculated how much force is needed to open the door, the twisting angles to unlatch the door, and how much force is needed to unlatch it.
“Commercially available systems are quite expensive and are usually not covered by insurance. What we have designed is an arm specifically to unlatch door knobs and door handles while being permanently mounted to a power wheelchair.” The idea for the arm began as a project while she was studying at the University of Massachusetts, and she has continued to develop it while working at Anybots. The system works by using a single motor, with a slip clutch allowing the arm to twist and push (or pull) at the same time. Erin said the key to its success was finding the right material for the fingers, something hard enough to grasp the handle, but supple enough to fit a range of shapes. She added: “I first tried flexible neoprene fingers, thinking that they could bend to grasp the knob, but these proved too thick and soft. Stiff plastic fingers with plates to constrain their sideways motion proved much more effective.” Although Dora is able to unlatch a number of door knobs and handles with similar characteristics, Erin said there are several limitations to the design that need to be addressed prior to using the robot in a rehabilitation environment.
Former Paralympic basketball player Ade Adepitan was the special guest at the annual British Healthcare Trades Association (BHTA) awards held at Hotel Russell in London. The television presenter was on hand to help present numerous awards on the evening, including the excellence awards sponsored by Assistive Technologies magazine.