Motion capture of the human body potentially holds great significance for exoskeleton robots, human-computer interaction, sports analysis, rehabilitation research, and many other areas. Dielectric elastomer sensors (DESs) are excellent candidates for wearable human motion capture systems because of their intrinsic characteristics of softness, light weight, and compliance. In this paper, DESs were applied to measure all component motions of the wrist joints. Five sensors were mounted to different positions on the wrist, and each one is for one component motion. To find the best position to mount the sensors, the distribution of the muscles is analyzed. Even so, the component motions and the deformation of the sensors are coupled; therefore, a decoupling method was developed. By the decoupling algorithm, all component motions can be measured with a precision of 5°, which meets the requirements of general motion capture systems.

Some applications are very sensitive to the weight of the robot, such as space manipulation or any untethered mobile manipulation. In this article, we designed a five-module unilaterally bending serial manipulator with length of 32 cm and a weight of only 18 g. The manipulator is driven by dielectric elastomer actuators (DEAs). Each module consists of a spatially closed tubular structure, which has the capability of large deformation while simultaneously maintaining torsional rigidity. The design is based on the buckling of columns. To achieve global deformation continuously, each module was controlled independently by a multichannel high-voltage power supply. As a demo, the manipulator was able to enter and exit a narrow L-shaped pipe. Experiments demonstrate that the manipulator driven by spatial DEAs can be super lightweight and can realize large continuous deformation.

Existing robots capable of hopping or running mostly rely on rigid actuators, but soft hopping or running robots based on muscle-like actuators have not yet been achieved. In this article, we report a tethered soft robot capable of hopping–running on smooth and rough surfaces with high speed. The hopping–running robot is composed of two soft joints that simulate the foreleg and hind leg driven by dielectric elastomer. The mass, length, width, and height of the robot are 6.5 g, 8.5 cm, 4.8 cm, and 50 cm, respectively. The robot can run at a speed of 51.83 cm/s (6.10 body lengths/s), which is much faster than previously reported locomotion robots driven by soft responsive materials. The robot also shows good adaptability to different terrains, such as marble, wood, rubber, sandpaper, and slopes. The robot can carry a load equal to its weight, can maintain a high locomotion speed, and demonstrates the potential ability to carry its power supply and control circuitry.

The dielectric elastomer minimum energy structure can realize large angular deformations by a small voltage-induced strain of the dielectric elastomer, so it is a suitable candidate to make a rotary joint for a soft robot. Driven with an alternating electric field, the joint deformation vibrational frequency follows the input voltage frequency. However, the authors find that if the rotational inertia increases such that the inertial torque makes the frame deform over a negative angle, then the joint motion will become complicated and the vibrational mode will alter with the change of voltage frequency. The vibration with the largest amplitude does not occur while the voltage frequency is equal to natural response frequency of the joint. Rather, the vibrational amplitude will be quite large over a range of other frequencies at which the vibrational frequency is half of the voltage frequency. This phenomenon was analyzed by a comparison of the timing sequences between voltage and joint vibration. This vibrational mode with the largest amplitude can be applied to the generation lift in a flapping wing actuated by dielectric elastomers.

This article presents the design, fabrication, and performance of a swimming robot actuated by dielectric elastomer actuators (DEAs). The robot is inspirited by the breaststroke swimming maneuver and consists of two DEAs to mimic two swimming legs. A special structure was explored to mimic the foot, and the structure could adjust its deformation intelligently during the biomimetic breaststroke; as a result it is referred to as a self-adaptive foot in this paper. The robot has a simple and compact structure, weighing only 14.3 g and having overall dimensions of 100 mm × 123 mm × 66 mm (length × width × height). When a voltage is applied to the legs, the two legs gradually and rapidly form a semi-enclosed space the can effectively increase the forward propulsion. The self-adaptive feet can change their water-facing area based on the direction of the water pressure. When powered off, the self-adaptive feet produce almost no backward force, and can even produce a slight forward propulsion force. In order to verify swimming performance, a robot with self-adaptive feet was fabricated and compared to another robot without self-adaptive feet. The results showed that the swimming speed of the robot with self-adaptive feet was 3.15 times faster than the robot without self-adaptive feet at 2 Hz. The maximum swimming speed of the robot with self-adaptive feet was 0.77 body lengths per second at a driving frequency 1.5 Hz and the amplitude of the square waveform voltage at 4.8 kV. In addition, the swimming robot can realize agile turning motions when applying the voltage to only one of the legs. The minimum turning radius was about 70 mm.