A control system consisting of proportional-integral (PI) controller and double phase advancer for a Magnetic Suspension and Balance System (MSBS) of Japan Aerospace Exploration Agency (JAXA) is explained in detail in this paper. Decoupling controller is also explained, which stabilizes the system by reducing the coupling motion between two axes. Furthermore, roles of control constants are made clear through parametric investigations considering the stability and disturbance suppression performance. Due to these investigation results, a course is shown to find proper control constants of PI controller and double phase advancer for an actual system.
This paper proposes a new mobility system for exploration under microgravity by using springs and linear actuators. In a microgravity, it is difficult to obtain horizontal velocity because the friction force between the robot and the ground is very small. By pushing off the ground, however, the robot can not only hop, but also obtain horizontal velocity. The proposed hopping robot consists of three masses and can push off the ground using springs. The robot can hop from the stationary state by transforming the elastic energy to kinetic energy using the springs and linear actuators. The robot can land without bouncing by transforming kinetic energy back to elastic energy. Free fall experiments demonstrate the landing performance of the proposed system.
This paper proposes a design method of a missile guidance system with robust control. The design method provides a compensator for the proportional navigation guidance law, explicitly considering the uncertainties by employing the μ-synthesis, a design method of robust control systems. The proposed method has two features: One is that the plant is modeled so that the feedback signal becomes the same as that of the proportional navigation, i.e., the relative velocity multiplied by the line-of-sight angular rate. The other is that the controlled output is chosen to be the component of the relative velocity perpendicular to the line of sight, instead of the line-of-sight angular rate, which is usually chosen in guidance law design based on modern control. Computer simulation is performed using a two-dimensional engagement model to show the effectiveness of the guidance law.
Idle spin phenomena were observed at rapid transient phase in liquid hydrogen pumps for rocket engines. Failure analyses were conducted and evaluation equations to estimate the shift of the operation point of the pump were derived in this paper. It was revealed that rapid fall of hydrogen flow rate resulted in decrease of pump efficiency which caused excessive temperature rise up to the saturation of the pump fluid.
We are studying next generation space robot technology for on-orbit assembling of large space structure. A new space robot end-effecter suitable to on-orbit structure assembling was designed and its prototype model was developed and tested. This paper describes the required function, performance for space robot end-effecter, new mechanism design and testing results of prototype model.
An Eulerian extensometer which gives Eulerian description of displacement has been proposed by the author for displacement measurement in material testing, and it has been shown that PC mouse, which is now an indispensable computer input device, can also serve as an Eulerian displacement meter. However, in material testing, Lagrangian description of displacement is needed to obtain specimen elongation and nominal strain. In the present study, Lagrangian velocity, i.e. the material derivative of displacement has been expressed as the sum of Eulerian velocity and the product of the displacement gradient in material coordinate system and Eulerian velocity. On this basis, a simple algorithm has been devised to obtain nominal strain as well as Lagrangian description of displacement in real time from the output of Eulerian displacement meter in one- and two-dimensional displacement field. Numerical verification has also been carried out to demonstrate the validity of the proposed method.