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For the accurate and continuous control of soft actuators in dynamic environments, the movements of the soft actuators must be monitored in real-time. To this end, various soft actuators capable of self-monitoring have been developed by separately integrating sensing devices into actuators. However, integrating such heterogeneous sensing components into soft actuators results in structural complexity, high manufacturing costs, and poor interfacial stability. Here, we report on intelligent pneumatic fiber-reinforced soft actuators with an inherent flexible proprioceptive sensor that uses only the essential components of typical fiber-reinforced soft actuators. The inherent flexible proprioceptive sensor is achieved by leveraging two parallel conductive microfibers around an elastomeric chamber of the soft actuator, which simultaneously acts as both a capacitive bending sensor and radial expansion limiting fibers of typical fiber-reinforced soft actuators. The proprioceptive soft actuator exhibits excellent mechanical actuation up to 240° bending motion and proprioceptive sensing performance with high sensitivity of 1.2 pF rad−1. Mathematical analysis and simulations of the soft actuator can effectively predict the bending actuation and capacitive responses against input pressures. We demonstrate that proprioceptive soft actuators can be used to construct a soft gripping system and prosthetic hand which express various hand gestures and perform dexterous manipulation with real-time proprioceptive sensing capability. [ABSTRACT FROM AUTHOR]

For safe coexistence between robots and humans, it is important for robots to detect the presence of nearby humans as well as any physical contacts made to its body. The design of a modular textile sensor array and an algorithm for multi‐modal sensing of human touches and other contacts with their contact forces proposed. Each sensor module in the array is capable of multi‐modal sensing, and the entire array with multiple modules requires only two wires to read the outputs from all the modules using band‐stop filter circuits. The proposed sensor system shows the structural modularity, achieved by simple fabrication of sequential lamination of conductive and non‐conductive textile materials, realizing electrical connections through conductive snap buttons that connect the modules to the circuit. The functional modularity is also achieved through the compensation algorithm, derived from the analysis of the transfer function in the frequency domain. The algorithm significantly reduces signal interferences between modules. The multi‐modality, the textile‐based design, and the structural and functional modularity of the proposed system enable practical applications to various robotic systems, including robotic skin for a collaborative robot, a wearable sensor, a robot hand sensor, and a human–computer interface, as demonstrated in this study. [ABSTRACT FROM AUTHOR]

The ability to grasp a wider range of objects in size and shape directly relates to the performance of robotic grippers. Adapting to complex geometries of objects requires large degrees of freedom to allow complex configurations. However, complexity in controlling many individual joints leads to introduction of underactuated mechanisms, in which traditional finger designs composed of revolute joints allow only flexion/extension motions. In this article, we propose a length-adjustable linkage mechanism in the underactuated finger controlled by an antagonistic tendon pair. The resulting gripper can elongate the fingers for an increased task space or shorten them for a finer spatial resolution. For tactile sensing, hyperelastic soft sensors are used to stretch with finger elongation. Contact pressures measured by the soft sensors are used in force-feedback control for which either the joint angles or the link lengths are adjusted. Lastly, a multimodal control scheme that combines elongation and flexion modes is demonstrated with tasks of dexterous manipulation. [ABSTRACT FROM AUTHOR]

In many soft sensor systems, external wires for connecting the sensors to control circuits have posed practical problems, in terms of compact form factors and physical robustness. This study proposes a design of soft sensor arrays that can operate with a drastically reduced number of wires without degrading the original performance. The proposed concept is an array of soft sensing modules, each of which consists of an inductor and a capacitor embedded next to the resistive sensing module, constructing a resistor-inductor-capacitor band-pass filter. By adjusting the values of the capacitance and the inductance, unique frequency band is assigned to each sensing module, enabling the distinctive detection using only two external wires regardless of the number of modules. The multi-touch sensing functionality of the system is analytically modeled and experimentally characterized. Taking advantage of the design, a fingertip tactile sensor and an insole foot pressure sensor are demonstrated as practical applications. [ABSTRACT FROM AUTHOR]

Cross-sectional geometry influences the pressure-controlled conductivity of liquid-phase metal channels embedded in an elastomer film. These soft microfluidic films may function as hyperelastic electric wiring or sensors that register the intensity of surface pressure. As pressure is applied to the elastomer, the cross-section of the embedded channel deforms, and the electrical resistance of the channel increases. In an effort to improve sensitivity and reduce sensor nonlinearity and hysteresis, we compare the electrical response of 0.25 mm2 channels with different cross-sectional geometries. We demonstrate that channels with a triangular or concave cross-section exhibit the least nonlinearity and hysteresis over pressures ranging from 0 to 70 kPa. These experimental results are in reasonable agreement with predictions made by theoretical calculations that we derive from elasticity and Ohm's Law. [ABSTRACT FROM AUTHOR]