Soft and continuously controllable grippers can be assembled from fluidic prestressed composite (FPC) actuators. Due to their highly deformable features, it is difficult to model such actuators for large deflections. This article proposes a new method for modeling large deflections of FPC actuators called the chained composite model (CCM) to characterize the quasi-static response to an applied fluid pressure and load. The CCM divides an FPC actuator into discrete elements and models each element by a small rotation model. The strain energy of each element and the work done by pressure and loads are computed using third-order displacement polynomials with unknown coefficients; then, the total energy is minimized to calculate stable shapes using the Rayleigh–Ritz method. This study provides a set of systematic design rules to help the robotics community create FPC actuators by understanding how their responses vary as a function of input forces and pressures for a number of modeling and design parameters. Composite actuators are fabricated and a soft gripper is developed to demonstrate the grasping ability of the FPC actuators. Pneumatic pressure and end loads are applied to the composite actuators, and their responses are measured. The modeled responses of the actuators are shown to be in agreement with the measured responses.

High injury severity occurs when a stiff robot arm hits an operator. Introducing compliance into robot systems reduces the impact and enables safe interaction, but at the expense of positioning performance and payload capacity. This paper presents a tunable stiffness mechanism for safe human-robot interaction based on discrete layer jamming. The proposed design of a discrete layer jamming mechanism is a robot link made of multiple thin layers of ABS and multiple clamps. By applying high clamping pressure to the laminates, the link behaves like a rigid link; reducing the clamping pressure softens the link which yields safer human-robot interaction. Compared to conventional pneumatic layer jamming, discrete layer jamming allows for simplicity of installation with dynamic actuators, faster control, greater portability since no air supply is needed, and no sealing issues. To validate the concept, this paper investigates a discrete layer jamming beam made of ten ABS laminates and two aluminum clamps that cover 10% of the surface of the beam. Stiffness tests have been performed, showing that around 17 times bending stiffness change is achieved by increasing the clamping pressure of two clamps from 0 to 1 MPa.