Static Characteristics of Fire Hose Actuators and Design of a Compliant Pneumatic Rotary Drive for Robotics

In this work, we present and explain in detail the design of a new type of pneumatic actuator made of fire hose, the fire hose actuator (FHA), see Fig. 1. We model the force output of this type of actuator and we compare the theoretic results to the data measured on the laboratory test stand. Furthermore, we present the design of a pneumatic rotary drive that is actuated by four of the above-mentioned FHAs. The drive unit features intrinsic compliance and it is capable of high-precision positioning. Due to these characteristics, the design concept of the rotary drive is suitable for the potential use in robotics, especially in human-robot collaboration. In addition, we model the static torque distribution of the rotary drive and we compare the theoretic results to the data measured on the realized laboratory test stand. Moreover, we discuss the most important characteristics of the rotary drive. Hence, we present measurements of the adjustable stiffness and we show that high-precision positioning is possible with the system, reaching in ideal areas every bit of the used 17-bit encoder with a resolution of 0.0027. Moreover, the drive unit is capable of continuous rotation while the maximum continuous torque possible is found to be 63.1 Nm.