project specification

Lightweight soft robotic arm

A bio inspired robotic arm combining elements of rigid and soft robotics. A robotic arm–wrist–hand system with seven degrees of freedom (DOFs). The shoulder and elbow each has two DOFs for two perpendicular rotational motions on each joint, and the hand has two DOFs for wrist rotations and one DOF for a grasp motion. The arm is pneumatically powered using custom-built McKibben type pneumatic artificial muscles, which are inflated and deflated using binary and proportional valves. The wrist and hand motions are actuated through servo-motors. In addition to the actuators, the arm is equipped with a potentiometer in each joint for detecting joint angle changes.

Specifications

Length117 cm
Weight1.2 kg
ActuatorsCustom build PAMs
Degrees of freedom (DOFs)7
Manufacturing technique3D Printing

Overview

A robotic arm–wrist–hand system with seven degrees of freedom (DOFs). The shoulder and elbow each has two DOFs for two perpendicular rotational motions on each joint, and the hand has two DOFs for wrist rotations and one DOF for a grasp motion. 

The arm is pneumatically powered using custom-built McKibben type pneumatic artificial muscles, which are inflated and deflated using binary and proportional valves. The wrist and hand motions are actuated through servo-motors. In addition to the actuators, the arm is equipped with a potentiometer in each joint for detecting joint angle changes.

The bioinspired robotic arm combines soft and rigid systems in a way that resembles the human arm in terms of structure, actuation, and degrees off reedom (DOFs). It consists of a lightweight skeleton made of carbon fiber composite tubes, 3D-printed rigid plastic joints,on-arm pneumatic artificial muscles (PAMs), and a servo-controlled underactuated hand. An external inflatable sleeve adds to the compliant nature of the air muscles by providing alayer of soft cushioning to dampen impacts. The internal structure allows for a higher degree of kine-matic accuracy than purely soft systems, and the use oflightweight materials and arm-mounted air muscles rendersthe arm lightweight as a whole and more physically com-pliant than purely rigid systems.

One of the main design benefits is that the robotic arm can operate safely in the presence of people, while still being relatively strong and precise.

References

Describes the design or the arm, joints, actuators amd hand. Discusses the control hardware, sensors, kinematic representation. Describes experiments, conclusion, and future work.

P. Ohta, L. Valle, J. King, et al. - 2017

Wevolver 2022