Orthostatic hypotension, deep vein thrombosis (DVT), and edema are venous system disorders that affect the lower limbs and are common causes of decreased work performance and affect the lives of many individuals. Compression devices, rotation of staff, and regular breaks can alleviate these problems. Active compression devices use air compression and require a pump, making them bulky. A calf muscle device that uses a dielectric elastomer as a soft actuator that is compact, lightweight, and resilient, making it convenient for use is developed. In this study, a physics-based model of the device is presented by combining the physics of a thin-walled dielectric elastomer vessel with the force interactions between the active vessel and the cylindrical passive elastomer within. The couplings between the two nonlinear elastic models are solved and a control-oriented model that is capable of capturing the pressure change experienced by the device under an applied voltage is established. A prototype of the device is made and characterized. The model is validated in the normal frequency range of the device. Human pulse signal tracking is then performed using adaptive iterative learning control (ILC) in a feedback loop. Experimental results have shown that the device can generate up to 10 Pa fluid pressure difference while tracking a human pulse signal with almost zero phase delay.Note to Practitioners—This paper describes a method that enhances blood flow using a comfortable soft cuff device. The device is made of dielectric elastomer which can generate contractions when it wraps around a lower limb to help circulate blood flow. Development of the cuff device could provide a preventive and proactive tool, as well as a rehabilitation tool, for regulating and improving blood flow. For example, this device could help a passenger who takes a long time flight to circulate his/her blood flow. This device could also help an athlete improve his/her muscle performance in highly intensive competitions. This paper details design, modeling, fabrication, and control of the device. A prototype of the device was fabricated and was able to generate enough contractions on an artificial lower limb to influence the blood pressure while tracking a human pulse signal. Experimental results have shown a great promise in enhancing blood flow with such a wearable and comfortable device.

Recent offshore drilling activities have dramatically bloomed oil and gas production. Due to extreme weather, such as hurricanes and tsunamis, offshore oil platforms may need to be constantly monitored in case of unexpected dangers. Using robots to monitor and prevent these dangerous situations is a cost-effective and safer solution compared to any human involvement. However, one major drawback for robotic intervention is the ability of the robot to operate water tight ship doors designed for marina facilities. Current studies have been focused on robots manipulating normal doors in people's daily life. However their presented methodology may not be suitable for opening heavy watertight ship doors since they have a special locking structure which needs much larger torque to open. This study explores the possibility of opening heavy watertight ship doors with an ordinary mobile robot under remote control. Given the watertight ship door’s unique structure, a door opening tool with a pawl mechanism is designed for a mobile robot, which consists of a robotic arm and a wheeled platform, to complete the task. Experimental results have shown that the mobile robot can operate the tool to open the door and transition through the door.

Three-dimensionally (3D) maneuverable robotic fish are highly desirable due to their abilities to explore and survey the underwater environment. Existing depth control mechanism is focused on using compressed air or piston to generate volume change, which makes the system bulky and impractical in a small size underwater robot. In this paper, a small and compact 3D maneuverable robotic fish is developed. Instead of using a compressed air tank, the robot is equipped with an on-board water electrolyzer to generate the gases for depth change. The fabricated robotic fish shows fast diving and rising performance. A servo motor is used to generate asymmetric flapping motion on the caudal fin, which leads to a two-dimensionally (2D) planar motion. A 3D dynamic model is then derived for the fabricated robotic fish. Several open-loop control experiments have been conducted to validate the model as well as the design. It has been demonstrated in the experimental results that the robot is capable of generating 3D motion. The robot can achieve 0.13 m/s forward velocity, 30.6 degree/s turning rate, and it takes about 5.5 s to dive to 0.55 m and 10 s to rise.

This paper presents modeling of robotic fish propelled by a hybrid tail with Servo and IPMC actuated two joints. The first joint is driven by a servo motor, which generates flapping motion for main propulsion. The second joint is actuated by a soft actuator, or ionic polymer-metal composite (IPMC) artificial muscle, which directs the propelled fluid for steering. A dynamic model is developed to capture the 2D motion dynamics of the robotic fish. The model fully captures the actuation dynamics of the IPMC soft actuator, two-link tail motion dynamics, and body motion dynamics. Experimental results have shown that the robotic fish is capable of swimming forward (up to 0.45 body length/second) and turning left and right (up to 40 degree/sec) with a small turning radius (less than half a body length). Finally, the dynamic model has been validated with experimental data, in terms of steady-state forward speed and turning speed versus the flapping frequency.