Soft Robotic Manipulators: Designs, Actuation, Stiffness Tuning, and Sensing

Abstract Soft robotic manipulators are continuum robots made of soft materials and flexible components. The goal of soft robotic manipulators research is to enable these manipulators to adapt their shapes to cluttered environments and to have safer interactions with human. However, there is still a problem with effectively using soft robotic manipulators in practical applications. The challenges of soft robotic manipulators in terms of materials and structure design, stiffness control, perception, and function control remain to be overcome. Here, an overview of recent advances in this field is presented, covering device architectures, actuation, variable stiffness, and sensing. Actuator technologies are discussed and roughly divided into three categories: a) tendon‐driven actuation, b) fluidic actuation, and c) stimuli‐responsive actuation, which is based on smart materials. Considering the working principle of stiffness variation technologies, stiffness variation technologies can be divided into two categories: a) using the interactions between structural elements, b) direct material rigidity tuning strategies. A briefly review of soft sensing technologies is presented. From the functional perspective, sensor technologies are divide into two categories: proprioception and exteroception. A conception for designing soft robotic manipulators is proposed from the perspective of soft robotic manipulator applications. Finally, the challenges this field faces are discussed.