This paper describes a new control algorithm for achieving any arbitrary attitude and angular velocity states of a rigid body, even fast and complicated tumbling rotations, under some practical constraints. This technique is expected to be applied for the attitude motion synchronization to capture a non-cooperative, tumbling object in such missions as removal of debris from orbit, servicing broken-down satellites for repairing or inspection, rescue of manned vehicles, etc. For this objective, we have developed a novel control algorithm called Free Motion Path Method (FMPM), which enables us to completely ignore a non-linearity effect in the dynamics by concentrating on some conservative quantities of the system. FMPM is an on-line control method and can be formulated as an open-loop or a closed-loop system. With FMPM, we can explicitly specify the maximum control torque constraint and also it realizes a certain kind of optimality. This paper examines an open-loop formulation of FMPM with some theoretical analyses and computer simulations.
This paper presents the flight experiments on the dynamics and control of a space robotic arm mounted on ETS-VII (Engineering Test Satellite VII). The experiments were successfully carried out to evaluate the performance of (1) reaction null-space based reactionless manipulation, (2) generalized Jacobian based inertial manipulation, (3) offset command based feedforward attitude control, and (4) bi-directional approach of non-holonomic path planning. Inertia parameters of ETS-VII is identified based on the momentum equation and the effect of gravity gradient torque is also evaluated.
The controller design method taking account of flying quality is proposed. Where it is assumed that pilot determines flying quality by CAP (control anticipation parameter). Because CAP condition is formulated in LMI forms, flying quality requirement can be introduced into controller design easily. When the LMIs have a solution, flying quality of closed-loop system is guaranteed. Flying quality condition is combined with robust stability condition and verified by numerical example.
Reconfigurable Brachiating space Robot consists of three 6-DOF arms to support various kinds of external vehicle activities by changing its arm configuration. This kind of robots requires topology-change adaptation in communicational system as well as mechanical composition. Distributed controller system is employed to realize its objectives and this paper discusses its communicational architecture that we have designed. Moreover, fault resilience method in the distributed system with several micro processing units is proposed. It targets realizing high availability on data processing function using process takeover and parallelism by software.
Three-dimensional oscillations of a supersonic opposing jet flow around a hemispherical nose are investigated through numerical analysis that consists of an efficient implicit algorithm. The results show that axially asymmetric oscillations are reproduced in both stable and unstable region, and that frequency of oscillation in unstable region agrees well with existing experimental results. On the basis of the numerical results, the mechanism of oscillation in unstable region suggested in former study of the author is quantitatively validated, and the mechanism of oscillation in stable region is newly presented here. Also in unstable region, unsteady aerodynamic force on the hemispherical nose is shown to be axially asymmetric and rotating in circumferential direction.
Boundary-layer transition measurements on an unswept wing of the Beechcraft Model 65 airplane in flight test were done prior to the launch of the NAL SST Non-Powered Experimental Airplane (NEXST). The main objectives of this experiment are to establish both measurement and diagnosis techniques for detecting the transition location by means of hot-film sensors, which are the similar type of sensors installed on the main wing of NEXST. A series of hot-film measurements showed a transition process, which is commonly seen in low-turbulence wind-tunnel tests. That is, although the output level of a hot-film at the beginning of transition was quite low, further downstream sensors detected unstable Tollmien-Schlichting waves, which finally led to turbulence. It was also observed that the center frequency of this instability wave is predictable.
A flying toy called Aerobie ® was invented by Adler in the US. The flight range of the toy is rather enormous, and it is one of the Guinness book world records. The authors were interested in the aerodynamic characteristics of the toy, and experimentally investigated annular plan form flat plates from which the toy was developed. It was found that L/D was improved and the center of pressure moved toward the center of gravity as the inner radius was increased.