Hideto Okada

Tokyo Tech CubeSat: CUTE-I - Design & Development of Flight Model and Future Plan -

Laboratory for Space Systems, Tokyo Institute of Technology finished development of CUTE-I and is waiting for its launch on June 30, 2003. CUTE-I is the first CubeSat of Tokyo Institute of Technology, that is a 10 cm-edge cube-sized satellite of less than 1kg mass. CUTE-I has three missions such as communication, attitude sensing and deployment. to establish a bus component design for pico satellites like the CubeSat. In parallel with the CUTE-I development, we also developed a separation mechanism that is used to separate CUTE-I from the launcher on orbit. In this paper, we describe the design of CUTE-I and the separation mechanism as well as results of environment tests such as long-range communication test, thermal vacuum test, vibration test and separation test. We also mention a Tokyo Tech future plan on our satellite development.

Closed-Form Specified-Fuel Commands for On-Off Thrusters

A procedure is presented for generating on‐off thruster commands for rest-to-rest slewing of flexible systems. The command profiles induce a low level of residual vibration and can be designed to use any desired amount of thruster fuel. A key advantage of the proposed method is that the commands are described by closed-form functions of the system parameters and the desired move distance. Performance measures such as maneuver speed, maximum transient deflection, and robustness to modeling errors indicate that the commands are attractive alternatives to time/fuel optimal commands that must be determined using a numerical optimization. Experimental results from a system driven by on‐off air thrusters verify the proposed method.

Experimental verification of real-time control for flexible systems with on-off actuators

A technique for driving a flexible system with on-off actuators is presented and experimentally verified. The control system is designed to move the rigid body of a structure a desired distance without causing residual vibration in the flexible modes. The on-off control actions are described by closed-form functions of the systems natural frequency, damping ratio, actuator force-to-mass ratio, and the desired move distance. Given the closed-form equations, the control sequence can be determined in real time without the need for numerical optimization. Performance measures of the proposed controller such as speed of response, actuator effort, peak transient deflection, and robustness to modeling errors are examined. Experiments performed on a flexible satellite testbed verify the utility of the proposed method.

Control of Flexible Satellites Using Analytic On-Off Thruster Commands

A method for real-time control of on-off thrusters is presented. The thruster control is designed to move the rigid body of a spacecraft without causing residual vibration in the flexible appendages. The switch times of the commands are described by closed-form functions of the system’s natural frequency, damping ratio, actuator force-tomass ratio, and the desired slew distance. Performance measures of the proposed commands such as, slew duration, fuel usage, peak transient deflection, and robustness to modeling errors are compared to time-optimal commands. Experiments on a satellite testbed that floats on air bearings and has a flexible appendage verify the utility of the approach.

JetGun Sat “TOPPU”

In this paper, we report a conceptual design of micro-satellite for the verification of formation flying technologies. This satellite is a type of mothership-daughtership configuration called TOPPU which means a gust wind. The two satellites are connected by a tether; the mothership satellite has a docking mechanism installed, and a reel mechanism as well as gas jet gun to perform various orbital experiments. The system design of TOPPU is discussed, as is the progress of satellite system development.

Ground experiment system of reconfigurable robot satellites

Future in-orbit servicing missions will include capturing, inspecting and repairing damaged satellites, constructing large space structures, and supporting EVA (extra vehicular activities) of astronauts. In order to conduct the above missions, we have proposed a system of reconfigurable robot satellite clusters. The system consists of multiple satellites with reconfigurable arms. Utilizing its reconfigurability and mobility, the system can perform the tasks as well as far-site installation of a reconfigurable arm for constructing and inspecting structures. In order to investigate the proposed system, we construct a ground experiment system consisting two configurable arm models, three floating satellite simulators with gas-thrusters and a ground station. One arm is a reconfigurables brachiating space robot, RBR we have developed and the other is a newly developed one that consists of two parts; an arm part of 5 degrees of freedom with two reconfigurable end-effectors and a pivot; a docking part with two degrees of freedom. In the paper, we introduce the experimental system and the reconfigurable arms and show the results of functional and demonstration experiments using the system.

Titech CanSat Project 2000: Report of Sub-orbital Flight and Balloon Experiment

We have participated in the ARLISS (A Rocket Launch International Student Satellite) project since 1999 to design, manufacture and operate small satellites on students’ initiative. These satellites called CanSat are the size of soft drink can (350ml). We launch CanSats from the Black Rock desert in Nevada to 12,000ft using an amateur rocket, and drop them with a parachute. In this paper, we describe the subsystem design, mission and some results of the experiments on each CanSat, and report the results of an additional experiment using a balloon.