Design of a Novel Sensing Method for a Pneumatic Artificial Muscle Actuator-Driven 2-Degrees of Freedom Parallel Joint

The development of soft actuators and robots has spurred interest in human-friendly robots and devices that can operate in proximity with living things. Researchers have used soft actuators to drive hybrid soft/rigid mechanical platforms with multiple degrees of freedom (DOFs) that are both compliant and produce precise motions. However, the addition of sensors on these systems for feedback control remains a critical issue as they require multiple sensors operating simultaneously while the system undergoes complex motions. This article introduces the use of two spring-tensioned tendons passing through angular encoders for yaw and pitch orientation measurement into a pneumatic artificial muscle-driven two DOFs platform. This system possesses several advantages such as having a large range of motion and enables feedback control of the joint for position control. The joint is shown to be able to follow diverse motion patterns and capable of operating through external disturbances and was implemented as the base joint of an inflatable member.