Soft pneumatic robotic grippers can be used to conduct a wide range of tasks in extreme environments as they are generally free of conductive or magnetic components. But the sensorization of these grippers can potentially make them unsuitable for such environments and lower their performance through the introduction of electronic components or conductive materials into their structure. This work introduces the design of a sensorized soft pneumatic gripper using hybrid optical fibers making use of rigid and hard segments to measure the bending deformation and the contact force at specific segments of the finger. Using rigid optical fibers, which has low optical loss, for optical signal transmission allows to place all electronic components outside and away from the gripper ensuring the structure of the gripper and its nearby components are non-conductive and non-magnetic. The utilization of rigid reinforcements on the soft pneumatic actuator also helps maintain the performance of the actuator close to existing non-sensorized soft pneumatic actuators. This sensorized actuator is then used in a proprioceptive soft robotic gripper capable of controlling its grasping force.

Robotic manipulators have been used inindustry for decades. However, their heavy mass and rigidity make them unsuitable for environments where they may coexist with humans. This has spurred interest in robotic arms with compliance in their joints using methods, such as impedance control. However, inherent compliance is safer, less computationally expensive, and does not require complex sensing solutions. In this article, the design of a sensorized hybrid hard-soft articulated joint using inflatable soft rubber bellows for actuation and simple angular potentiometers for angular position sensing is presented. The joint is hybrid in the sense that it combines rigid motion with soft actuation. This design allows for a simple yet effective solution that combines the precise sensing of rigid manipulators with the compliance of soft ones. Closed-loop control of this joint was implemented and it was capable of following a given trajectory while rejecting disturbances. This design was then extended to a two degrees of freedom (DOFs) joint with the path following capability, and then, integrated with a rigid base joint to form a 6-DOFs hybrid robotic manipulator for use in small retail businesses. This manipulator can handle payloads up to 1 kg over a large work area and was tested for pick-and-place operations.

This article presents design, fabrication, characterization, and experimental verification of a new sensing method (soft optical sensing) for pneumatic artificial muscle (PAM) actuators. Soft optical waveguides are designed and fabricated using the proposed modified stiffness concept for soft sensors. The design of the sensor allows us to measure both contraction and force of a PAM actuator under loaded conditions. This proposed method makes it possible to have a highly sensitive actuator system with linear contraction sensing. The sensorized PAMs are supposed to work in high-pressure applications with the ability to be used repeatedly without significant degradation in signal quality. To characterize and validate the proposed method, two PAM actuators make use of two separately designed test systems to plot and model the characteristic curves. Finally, the validation for control is provided using measured sensor data as feedback to the controller.

Myoelectric prostheses assist users to live their daily lives. However, the majority of users are primarily confined to forearm amputees because the surface electromyography (sEMG) that understands the motion intents should be acquired from a residual limb for control of the myoelectric prosthesis. This study proposes a novel fabric vest socket that includes embroidered electrodes suitable for a high-level upper amputee, especially for shoulder disarticulation. The fabric vest socket consists of rigid support and a fabric vest with embroidered electrodes. Several experiments were conducted to verify the practicality of the developed vest socket with embroidered electrodes. The sEMG signals were measured using commercial Ag/AgCl electrodes for a comparison to verify the performance of the embroidered electrodes in terms of signal amplitudes, the skin-electrode impedance, and signal-to-noise ratio (SNR). These results showed that the embroidered electrodes were as effective as the commercial electrodes. Then, posture classification was carried out by able-bodied subjects for the usability of the developed vest socket. The average classification accuracy for each subject reached 97.92%, and for all the subjects it was 93.2%. In other words, the fabric vest socket with the embroidered electrodes could measure sEMG signals with high accuracy. Therefore, it is expected that it can be readily worn by high-level amputees to control their myoelectric prostheses, as well as it is cost effective for fabrication as compared with the traditional socket.

The manufacturing and assembly of soft actuators may seem like a straightforward affair, but various tools, equipment and specific know-how are required to build these actuators. Assembling them into soft robots can sometimes lead to numerous difficulties and often requires permanent assemblies of the components. Similarly, minimizing the number of components in more complex designs and the scaling of component to build larger structures can often require significant redesigns. There is a need for an easy to assemble and disassemble soft robotic actuator that helps minimize the number of components and is easy to scale in size. This paper introduces a simple assembly method for a soft inflatable joint capable of bidirectional motion that uses a rigid constriction with parallel slits in which inflatable tubes are inserted and whose ratio of pressures determines the bending angle of the joint. This concept enables the non-permanent and reversible assembly of inflatable robots, is highly scalable, and can help minimize the number of parts in a soft robot by placing multiple constriction-based joints on a single load-bearing inflatable tube. This concept is then implemented in a robotic manipulator with three degrees of freedom and a robotic hand as well as a large-scale quadruped robot with a leg length exceeding one meter.