Department of Computer Science of University of Massachusetts Lowell (UML) observed a robot named DORA. This robot is designed to help people who use wheelchairs to open the door.
A low cost robot arm system is developed that will increase a person’s accessibility to indoor spaces by unlatching door knobs and door handles. Implemented is a minimized arm configuration for use with a wheelchair or mobile platform and a gripper design that utilizes only a single motor to turn door knobs and door handles. This proof of concept prototype demonstrates how an arm with many degrees of freedom is not required if we target the expectations for its use.
Simulation has shown that the arm configuration can be reduced to three controllable degrees of freedom because the position wheelchair can be leveraged and the two degrees of freedom required to match the gripper with the plane of the door could be passive. Therefore, the arm consists of three motorized joints: a cylindrical joint swinging the arm side to side, a rotational joint swinging at angles up and down, and a sliding link that will extend the arm back and forth to increase its length. This design is otherwise known as a Cartesian robot configuration. The gripper will use a fourth motor for actuation and it is attached to the arm using a high misalignment spring loaded universal joint. The universal joint will also allow for passive adjustment of the angle on approach and, after the door knob has been unlatched, while the user is pushing or pulling the door open with their chair.
View the demonstration of the robotic arm when opening the door: