Energy Dissipation during Surface Interaction of an Underactuated Robot for Planetary Exploration

The article summarizes research on essential contributors to energy dissipation in an actuator for an exemplary planetary exploration hopping robot. It was demonstrated that contact dynamics could vary significantly depending on the surface type. As a result, regolith is a significant uncertainty factor to the control loop and plays a significant contribution in the control system development of future planetary exploration robots. The actual prototype of the actuating mechanism was tested on a reference surface and then compared with various surfaces (i.e., Syar, quartz sand, expanded clay, and quartz aggregate) to estimate the dissipation of the energy in the initial phase of hopping. Test outcomes are compared with multibody analysis. The research enhances trajectory planning and adaptive control of future hopping robots by determining three significant types of energy losses in the system and, most importantly, determining energy dissipation coefficients in contact with the various surfaces (i.e., from 4% to 53% depending on the surface type). The actual step-by-step methodology is proposed to analyze energy dissipation aspects for a limited number of runs, as it is a case for space systems.

Hopping Robot: Current Status and Future Perspectives

Background: Search and rescue in high-risk situations and searches in unknown environments pose certain threats to human physical life. The development of mobile robots with exploratory capabilities that can be adapted to complex sites, with high mobility and high obstacle-crossing capabilities, is therefore a research trend. Existing wheeled and tracked mobile robots have excellent locomotion, but they are less adaptable and less efficient when faced with complex terrain or outer space environments. Therefore, how to increase the obstacle-crossing ability and improve the movement efficiency of mobile robots has become a research hotspot in the field of mobile robotics. Objective: To introduce the classification, characteristics and development of existing hopping robots. Methods: The various products and patents of hopping robots are summarized, and the structural features, differences and applications of typical hopping robots are introduced. Results: By analyzing a variety of hopping robots, the typical characteristics and the current problems of hopping robots are analyzed, the development trend of hopping robots is prospected, the current research status of hopping robots are discussed and the future prospects are carried out. Conclusion: Hopping robots can be divided into mechanical energy drive, combustion energy drive and new energy drive according to the driving method. Depending on the drive energy used, jumping robots can achieve a jump height 0.5-30 times higher than their own size, and combined with a specific mechanical structure design, they have the characteristics of high explosive, high mobility, and can solve interstellar exploration, terrain exploration and rescue problems. Compared to mechanical energy drives, combustion chemistry is two orders of magnitude more energy intensive than even the highest performing batteries. The use of recycled renewable energy solves the energy self-loading problem of chemical combustion drives and is more environmentally friendly than the two previous types of new energy drives. Therefore, such products should be invented and patented in the future.

Models of a hybrid wheeled hopping self-balanced robot

Combining wheeled structure with hopping mechanism, this paper purposes a self-balanced hopping robot with hybrid motion pattern. The main actuator which is the cylindrical cam, optimized by particle swarm optimization (PSO), is equipped with the motor to control the hopping motion. Robotic system dynamics model is established and solved by Lagrangian method. After linearization, control characteristics of the system is obtained by classical control theory based on dynamics equations. By applying Adams and Matlab to simulate the system, hopping locomotion and self-balanced capability are validated respectively, and result shows that jump height can reach 750 mm theoretically. Then PID control scheme is developed and specific models of hardware and software are settled down accordingly. Finally, prototype is implemented and series of hopping experiments are conducted, showing that with different projectile angle, prototype can jump 550 mm in height and 460 mm in length, transcending majority of other existing hopping robots.

Dynamic Modeling and Control of a Novel One-Legged Hopping Robot

SUMMARY In this article, a novel mechanism for planar one-legged hopping robots is proposed. The robot consists of a flat foot which is pinned to the leg and a reciprocating mass which is connected to the leg via a prismatic joint. The proposed mechanism performs the hopping by transferring linear momentum between the reciprocating mass and its main body. The nonlinear equations of the motion of the robot are derived using the Euler–Lagrange equations. To accomplish a stable jump, appropriate trajectories have been planned. To guarantee a stable response for this nonlinear system, a sliding-mode controller is implemented. The performance of the hopping robot is investigated through numerical simulations. The results confirm the stability of the hopping robot through the jump cycle on a flat surface and in climbing up and down ramp and stairs.