A new mechanism of smart jumping robot for lunar or planetary satellites exploration

For planetary exploration, small robots of just a few kilograms installed in the main spacecraft have a lot of advantages. Small robots can provide us with a wide range of exploration opportunities by using multi-robots, technical demonstrations, and science missions which require detailed data acquisition. There are not only mission advantages, but they can also be developed in a short period of time and at a low cost. MINERVA, MINERVA II, MASCOT are examples which are installed in the main spacecraft for surface exploration. In order to move on the surface of a “low gravity” object, like the Moon by a small robot, there are several options of locomotion, such as jumping, wheels, and legs. Wheel locomotion cannot step over obstacles where the size is bigger than the wheel radius, and the structure of leg locomotion is a very complicated piece of machinery and requires a lot of actuators. However, jumping locomotion is capable of moving a long distance by one action and the number of actuators required for jumping capability is very small. In addition, it can travel a longer distance on a planet or satellite which has a gravity lower than the Earth. For instance, it can jump 6 times longer on the Moon than on the Earth. To realize jumping locomotion for small robots in a low gravity environment, the mechanism has to meet the following functional requirements. (1) it can charge the required jumping energy, (2) it can release the energy instantly, (3) it can change the amount of the energy needed to control jumping distance, (4) it doesn't consume resources such as fuel and should be able to repeat the movement, (5) it has a ground contact part to apply power, (6) the size should be small and the weight should be small (7) it can move in a space environment (vacuum, high radiation). We studied some jumping mechanism concepts to meet these requirements. Our design of the mechanism uses springs to charge the energy and they are supported and connected to the shaft structure. A jumping pad is attached to the end of the structure and pushes the ground and robot so it can jump from the ground. For actuation, only one motor is used. In our mechanism, a one-way clutch is used to change from energy charge mode to release mode. This mode change is executed by changing the direction of motor rotation. After jumping, it can change the mode to energy charge mode again. The authors have developed a research model of the jumping rover which the jumping mechanism is mounted on. This model is developed for a lunar exploration mission. Science mission equipment mock-ups and wheels are also mounted on the model. The wheel is used to control the jumping direction. In this paper, our design of the jumping mechanism, development of a research model, and test results are presented in detail.