A Novel Inflatable Tendon Driven Manipulator With Constant Volume

Abstract

Tensegrity and cable driven systems are used in robotics when lightness and stiffness are required. Inflatable structures are well known as tensegrity structures. In this case the skin is the tension member and the air is the compression member. Such structures have already been used in robotics to create cable driven arms made of inflatable links separated by mechanical joints. In this paper we propose a novel inflatable manipulator in which the joints are fully integrated to the inflatable structure. This design allows us to make inflatable robots with a constant and continuous pressurized volume with no loss of strength at the joints. A mechanical model has been developed and validated by experiments. We also present an appropriate cable-based actuation system that controls the joints without coupling.

Proposal of tendon-driven elastic telescopic arm and initial bending experiment

“…The circles show the point where the tension distribution of the attached number converges. Starting from the blue circle (1), following the blue solid line and red dashed line, ending at red circle (1). Tip displacement was obtained within about 1400 mm in both vertical and horizontal directions.…”

“…The weight of the mechanism was reduced and a weight compensation mechanism was installed as an attempt to overcome the constraint caused by the weight of the manipulator. As an example of weight reduction, there is the application of special rotation joints [1] and the arrangement of actuators concentrated on the base by driving force transmission using wires [2]. As an example of the weight compensation mechanism, there is a method of loading a part of gravity torque on a spring or a wire [3] [4], as well as a method of supporting torque by the structure itself.…”

“…The SCARA is an arm that limits the rotation node to only the vertical axis. It can experience a moment due to the weight of the entire structure, because forces in the vertical direction are not received in 1 T.Fujioka, G.Endo, K.Suzumori and H.Nabae are with the Department of School of Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguroku, Tokyo, 152-8552, Japan fujioka.t.aa@m.titech.ac.jp the axis of the rotation node. The range of movement in the vertical direction becomes narrow because it is necessary to keep the arm horizontal.…”

Tendon-driven Elastic Telescopic Arm -Integration of Linear Motion and Bending Motion-

“…For reducing the weight of a mechanism, there is a method of using the inflatable joint [1] which is integrated with the structure without additional mechanism or a method of transmitting power using a rope and collecting an actuator at the base [2]. As an example of the weight compensation mechanism, there is a method of supporting a gravity torque by using springs or ropes [3] [4], or there is a method of supporting it by the structure itself.…”

“…The linearly extending arm has the same structure as that found *This work was supported by the New Energy and Industrial Technology Development Organization (NEDO). 1 in fire truck ladders. Since there is no rotation axis in linear motion, the entire structure can support the gravity torque.…”