Saburo Matunaga

Ground experiment system for dual-manipulator-based capture of damaged satellites

A robot satellite with dual-manipulators is one of the choices to capture damaged satellites in orbit. We have constructed a ground experiment simulator system including two 7-degree-of-freedom (DOF) manipulators as a chaser satellite model and floating testbeds on a flat floor as target satellite models. This system is a tele-operation ground experiment system and consists of the following subsystems: the robot system, vision system, manipulator operating system, ground control system and damage satellite model system. Using this system, we will study feasible capturing and berthing methods of damaged satellites using dual-manipulators. In the paper we explain the detailed description of the system and report the results of fundamental capture experiments.

Operational aspects of a super redundant space robot with reconfiguration and brachiating capability

A super-redundant space robot with reconfiguration and brachiating capability (RBR) has been developed at Department of Mechano-Aerospace Engineering of Titech. The RBR is designed to operate on a space station exposed facility as well as unmanned free-flying robotic spacecraft. It consists of a center hub and three manipulator arms. Each arm has 6 DOF with an additional end-effector, and one in the center hub, leading to 24 actuators driven independently. In addition, each arm can be autonomously operated or slaved by a higher authority in the center hub. Each arm is mechanically detachable from the center hub and can be plugged into any of the connection ports with power and signal transmission capabilities. Thus, the RBR can move on the spacecraft and perform various tasks such as monitoring, payload carrying and placement, capturing and berthing, etc. This paper describes a fundamental function with emphasis on the distributed controllers and communication systems of the RBR.

Research and development of tethered satellite cluster systems

We propose the concept of tethered satellite cluster systems, as an application of the RoboSat clusters. The system consists of some satellites joined by tethers, and keeps and changes the constellation with tension/length control of the tethers to perform various orbit service missions. We formulate the motion of the system in order to analyze the dynamics and establish the methods of coordinated control of tension and attitude of the satellite. In addition, we develop a ground experiment system including a reel mechanism for the tethered satellite cluster systems. We outline the system components and show results of the fundamental experiments for verification of the reel mechanism and the control methods.

Dynamics and control of space robot brachiating motion using handrails

We investigate brachiating motion dynamics and control of space robot using handrails on in-orbit structures in order to inspect, repair and/or construct them. We deal with one arm type space robot based on the Reconfigurable Brachiating space Robot (RBR). We conduct a micro-gravity flight experiment of the RBR, and we identify kinematical and dynamical parameters of the robot arm. Then, we conduct numerical simulations of 6 DOF robot arm dynamics under the constraint within a two-dimensional plane. It is assumed that the robot arm moves on a large space structure using handrails attached to the structure. When the handrail slowly vibrates due to flexibility of the large structure, then the robot behavior is influenced by its fluctuation. In this paper, we show the simulation results of brachiating motion and discuss the flexibility effects to the robot motion.

Capability evaluation of reconfigurable brachiating space robot

We developed the system of a reconfigurable brachiating space robot (RBR). This space robot is designed based upon the modular design, cable reduction and distributed control technique. This robot is capable of moving over the Japanese experimental module of the International Space Station in a brachiating manner and also capable of arm reconfiguration according to the various task requirements. This paper presents the capabilities of the RBR, mainly, the controllability for the distributed control, the capability of grasping handrails and the reconfiguration mechanism. We conduct experiments for evaluation of these capabilities of the RBR, and explain the result of these experiments.

Numerical computation of reconfigurable multibody dynamics

There has been much research on capturing and berthing damaged satellites in space, and such systems are categorized as reconfigurable multibody systems whose constraint conditions are time varying. On the other hand the theory for reconfigurable multibody dynamics is not well developed. There are many technical issues such as the dynamics algorithm with topological changes, contact dynamics, collision detection and computation of Jacobian matrices concerned with constraint conditions, and so on. We propose the algorithms to solve and implement some of these issues.

Impact analysis of linked manipulator systems using wave propagation theory

The formulation and impact dynamic response of an n-link flexible manipulator systems using stress wave propagation theory is discussed. The usual method for deriving the intermittent motion of multibody systems has some limitations, such as the need to specify the value of the coefficient of restitution. In our analysis we apply wave propagation theory, which takes into account the mechanical properties and the initial velocities of the impacting bodies, and extend this theory to multibody systems. In the analysis, the manipulator links are modeled as beams, and simple one-dimensional theory is used for the longitudinal displacements and torsion, while Bernoulli-Euler theory is used for flexural displacements. We only consider the linear elasticity of the impacting body and neglect the plasticity and fracture. By using wave propagation theory, we can obtain the impact stress history, and realize that the coefficient of restitution depends on the dimension or shape of the bodies.

Titech micro-satellite model: CanSat for sub-orbital flight

We had the opportunity to launch prototype CanSats, small satellites the size of a soft drink can, on an amateur rocket in September 1999 (ARLISS: A Rocket Launched International Student Satellites). We developed four CanSats for ARLISS: CanSat Type1 and Type2 missions are experiments of two different types of mechanisms for tether applications, CanSat Type3, is a communications and electronic devices test satellite, and CanSat Type4 is equipped with CCD camera and transmits video images. The development period is less than 5 months. In this paper, we describe 4 CanSats missions, subsystem designs including the ground station and the results of ARLISS experiments.

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.