Kazuo Machida

Application of intelligent monitoring for super long distance teleoperation

Time delay and limited communication capacity are the primary constraints in super-long distance telerobotic systems such as space telerobotic systems. Intelligent monitoring is efficient for this problem to provide a function which selects important scenes to help the operator through a monitoring camera. We constructed a telerobotic testbed which includes a connection through the international ISDN and typical space structure (space robot, truss structure land ORU). We conducted trans-Pacific teleoperation experiments using the testbed in ETL as the remote site and a telerobotic console at JPL (Jet Propulsion Laboratory in Pasadena, California) as a local site. Experimental results showed intelligent monitoring to be effective for the above problems.

Maneuvering And Manipulation Of Flying Space Telerobotics System

A free flying telerobotics system has great potential for servicing future large unmanned space facilities because of its flexible maneuver- ability in space. We have been developing a ground model of the Astronaut Reference Flying Robot performing in-orbit servicing in the manner of an a stronaut with This paper deals with tonomous flying robot control structure of a duced for autonomous for a dynamic flying a manned maneuvering unit. control problems of the au- in a no-gravity field. The multilayered system is intro- operation. A control method maneuver in the proximity of the space facility using non-linear compensation is proposed. Moreover, simplified manipulation methods using inertial sensor compensation and ac- tive limp control are proposed for capturing a pay- load, and the effectiveness is shown through numer- ical simulation and experiments on an air bearing testbed. The demonstration experiment for the au- tonomous satellite retrieval mission was success- fully implemented on the testbed. arm using the inverse dynamics method (l, 21. Several studies on arm slew control under attitude disturbance due to arm motion were carried out using the kinematics of a base free robot (3,4). These methods require accurate knowledge of the mass/inertia property of a robot, and complex computation. Furthermore, the torque control of the actuator and thrust force of gas jet thrusters are necessary in the case of inverse dynamics control. These are not realistic for practical applications in space. Moreover, there are few papers discussing other important maneuvers before and after arm slew control required for in-orbit servicing. It is important to study control problems for overall task achievement including the flying maneuver and manipulation with momentum exchange according to practical space missions. In this paper, we deal with a series of control problems in a satellite retrieval mission which requires flying approach, capturing, docking and berthing. We propose new simplified algorithms for the maneuvers which accommodate space applications. We have been developing an experiment model of a free flying telerobotics system with a triple arm and propulsion system, working on a two-dimensional air bearing testbed. This paper presents the high-level control architecture of the robot, and presents the flying maneuver and manipulation methods under a no-gravity field. Robust coordinate control between the

DIAGNOSIS OF SMALL SATELLITES USING MULTIPLE SENSORS AND A ROBOT

Four diagnostic methods for small satellite malfunction using several types of sensors and a robot are proposed and tested experimentally. The four methods are (1) averaging method of probability, (2) small probability deleting method, (3) Bayesian network method and (4) correlation matrix method. The reasoning method of the malfunction essentially has a probabilistic property. We limit the malfunction of the solar paddle to five kinds and use symptom parameters to identify the malfunction by inference. In our experiment, all four methods are effective. In particular, Bayesian network method produces excellent results; however, in this case a single failure may cause total failure. The averaging method and correlation matrix method generate rather ambiguous results; however, they are hardly affected by failure. In many cases, the small probability deleting method works well, however, a single failure may cause total failure.

Simulations and Experiments of Laser Guidance for Flying Effector

A new method of guidance for Flying Effector that is a free flying space robot with a tether for supporting large space structure assembly and maintenance is proposed. The guidance system uses a laser beam to direct the flying path of Flying Effector, and an image sensor with half mirrors as a laser receiver. The Flying Effector model was developed. The model detected half-mirror -reflective laser beams, to recognize its relative position and attitude to the laser beam. Three-dimensional numerical simulations and two-dimensional experiments were carried out. The results show the reliability of the laser guidance system. Nomenclature (X,Y,Z) = relative vertical position, horizontal position to laser beam, and distance from the start point ) , , ( y p r θ θ θ = relative roll, pitch, and yaw angle to laser beam (U,V,W) = relative vertical velocity, horizontal velocity to laser beam, and velocity from the start point ( ) y p r ω ω ω , , = relative roll, pitch, and yaw rate to laser beam (Fx,Fy) = thruster force in the X direction and Y direction (Ty, Tx) = pitch torque and yaw torque d1 = distance between half mirrors d2 = distance between half mirror and photosensitive plate P. ( ) Zi Xi Δ Δ , = positions of reflective laser spots on photosensitive plate P (i=1, 2, 3) v,w = camera sensor noise vector and disturbance vector M = mass of Flying Effector (Iy, Ix) = Fly ing Effector’s moment of inertia

Study on Super Long Distance Space Telerobotics

Telerobotics research for Super Long Distance has been underway between MITI of Japan and NASA JPL of United States. Foe this telerobotics, the limited amount of data transfer, communication delay and the uncertainty of robot environment will be the major issues. To overcome these problems, a telerobotic system, with a knowledge base for object handling, an environment model and a hybrid compliance/force control, has been constructed. With this system, a truss structure in Electrotechnical Lab. in Japan was successfully deployed from JPL in United States. The experimental set-up with built-in software and test results are described in this paper.

Design and Fabrication of Satellite On-Board Type Ion Engine Control System

An ion engine is one of the most promising electric thrusters for satellite position control because of its high specific impulse. As the engine must be operated thousands of times during the station keeping mission, an autonomous control function is necessary. The engine is nonlinear multivariable system which is controlled by 10 power supplies. The reguirements about power, peak current and start-up time are imposed on the control system. The analysis and synthesis of the sequence control system are performed by the simulation which includes the thermal and plasma models. The trajectories of the temperature transition are analized for stabilizing the discharge process. T_ he introductions of some delay times and soft controls are effective for reliable engine operation. The fabricated system is tested and sufficient performances are verified. Keyword: ion engine, power conditioner, plasma process control, simulation, satellite control thruster

Design of Ion Thruster System for Satellite Position Control

Abstract An ion thruster is one of the most promising electric thrusters for satellite control because of its high specific impulse. As the thruster must be operated thousands of times during the station keeping mission, an autonomous control function is necessary for the propulsion system. The control system design and fabrication of the ion thruster system are described. The thruster is a nonlinear-multivariable system and its response is complex due to plasma characteristics. The simulation system which includes thermal and plasma models is derived for a design tool. The control sequence is designed under the constraints of input power and the start up time of the thruster. Some tests are carried out for the fabricated system and the sufficient performances are verified.