3-D Printed Telescopic Actuator for Bidirectional Actuation With Large Range of Motion

Robots made from soft and compliant materials offer a promising alternative to traditional rigid robots, particularly in human–robot collaborative environments due to their inherent safety. Pneumatic artificial muscles (PAMs) play a critical role in this field, serving as compliant actuators capable of generating substantial forces. However, this type of actuator still faces challenges in generating bidirectional force over a large range of motion. In this article, we introduce a three-dimensional (3-D)-printed PAM with a telescopic structure using a nested structure. The actuator's large volumetric deformation enables it to generate high bidirectional forces using positive and negative pressures, while also providing a wide range of motion with significant extension and contraction ratios. The use of 3-D printing not only simplifies the design and fabrication process but also offers significant advantages in mass production and industrial implementation. The proposed actuator can generate an extension blocked force of 659 N with an extension ratio of 447.1% and contract with payloads up to 7 kg up to a contraction ratio of 76.9%. A rotational configuration of the actuator is also presented with a blocked torque of 18.5 Nm. These actuators were then implemented into grippers and extendable links for robotic manipulators.