Inertial driving-type actuator
The word actuatorEmay not be understandable but, putting it simply, it means a thing that moves to work.EFor example, a motor is regarded as an actuator. The science-fictional sounding artificial muscleEis also classified as an actuator.
Under the harsh environment of space, there are cases where we cannot use motors. When temperature is very high or low, magnetic strength becomes low or lost and, eventually, motors sometimes fail to run.
Magnet force is often used in MEMS field, but the static electricity (electrostatic force) is rather preferred. This is because with electrostatic force, the actuator structure remains simple and it can function in principle at both high and low temperatures. MEMS actuator using electrostatic force also has weak points, however, in that the force generated is very small and moving distance is short.
To overcome these shortcomings, we are researching an actuator that can save small force and output it. As illustrated in Fig. 3, a whole chip moves by the impact caused by the collision of a Mass against an stopper. This type of actuator is called an inertial driving-type actuator.E
Have you heard of the Mexican jumping bean? A moth larva parasitizes the seed of this plant, causing the whole seed to move when the larva moves. The inertial driving-type actuator should be called the MEMS version of the Mexican jumping bean. Although the movement per collision is short, the distance can be increased by repeated collisions.
Fig. 4 shows the inertial driving-type actuator we fabricated. The advantages of this actuator are: it can move unlimited distances so long as power is provided; and the amount of generated power is large compared to other actuators using electrostatic force. The actuator cannot yet generate much power, but it can output enough to carry a small object. We intend to increase the generated power, or to generate greater power by deploying a number of actuators at the same time.
Toward the future
As MEMS technology advances, what will happen in the space field?
It is expected that satellites and explorers will continue to be downsized by the adoption of MEMS and other technology. Of course, in order to make them very small, there are many challenges to be met.
We imagine that, in the future, a small mobile phone-sized satellite could fly around the earth or observe stars. Tiny explorers as big as ants could be deployed around a distant celestial body to explore it, or to join forces to construct a micro-base on it. I believe that MEMS technology will be used in such scenes and activities.