# A Jumping Robot Driven by a Dielectric Elastomer Actuator
## 1 Introduction  
Jumping robots can easily jump over obstacles or trenches of their own size, and even those several times their size. Compared with wheeled or tracked mobile robots [1; 2; 3], they have better terrain adaptation and autonomous motion capabilities [4] and have broad application prospects in deep space exploration, terrain survey, and post-disaster search and rescue. The key to these jumping robots is how to achieve the jumping motion, and several methods for this have been developed. To cross rugged terrain in interstellar exploration, NASA designed three generations of jumping robots which store energy in the compression springs driven by the motor, to complete the adjustment of direction, take-off, and landing [5; 6; 7]. [PERSON]. [PERSON] et al. designed a jumping robot called MINERVA, which uses a motor to rotate the internal wister and is thus bounced by the reaction force against the ground [8]. [PERSON] et al. proposed a torsion spring leg jumping robot with capabilities of super jumping and continuous motion [9]. [PERSON] et al. presented a new design for settlement of the take-off angle and steering mechanism for a combustion piston-type hopping robot [10]. With the diversification of the working environment and the increasing complexity of performing tasks, the robot is required to be simpler but more compact in structure, lighter in weight, and more flexible in movement. Therefore, greater demands are proposed for the actuators of the robot. In recent years, researchers have developed several types of actuators. [PERSON] et al. presented the DEA: an insect-sized (40 mm long), fast (30 mm/s tethered, 12 mm/s untethered), ultralight (1 g) autonomous legged soft robot driven by DEAs (dielectric elastomer actuators) [11]. [PERSON] et al. proposed the Peano-HASEL (hydraulically amplified self-healing electrostatic) actuators; these prototypical devices demonstrated controllable linear contraction up to 10%, a strain rate of 900% persecond, actuation at 50 Hz, and the ability to lift more than 200 times their weight [12]. [PERSON]. [PERSON] et al. presented a shape memory alloy (SMA)-fishing line actuator, which combined fishing line and SMAs to form novel artificial muscle actuators [13]. Among them, dielectric elastomer (DE), a soft material that can undergo significant deformation when stimulated by an electric field, shows great potential. It has attracted more and more attention due to its merits of large strain, high energy density, fast response speed, and light weight [14; 15]. These merits endow dielectric elastomer actuators (DEAs) with characteristics of direct external work, low energy loss, and good adaptability for various working environments. Up to now, many robots driven by DEAs have been developed. [PERSON] et al. took advantage of the high response speed of DEAs to develop a micro-aircraft with high-frequency-vibrating wings; the flexibility and light weight of the DEA protected it from falling off when collision happened [16]. [PERSON] et al. applied the principle of the minimum energy structure of the DEA to the pectoral fin of robotic fish to achieve high speed under water [17]. DEAs not only provide driving force, but also can be used as the main body of the robot. Their high plasticity allow the structure to be adjusted according to the actual situation. Therefore, compared to robots driven by motors with standardized size and mass, DEA-based robots can be more compact in structure and lighter in weight. However, a single-layer DEA can only provide limited output force (about 1.6 N) [18], which only meets the requirement of a light-load robot. If the robot is to be equipped with heavier detection devices in the future, it is difficult for the DEA to meet the requirements. Stacking multiple layers of DE films is one common technique used to increase output force [19]. For example, [PERSON] et al. proposed a stacked dielectric elastomer actuator for tensile force transmission, which could lift a weight more than 500 times its own and had an energy density of 12.9 J/kg [20].