M-TRAN (Modular Transformer) is a self-reconfigurable modular robot that has been developed by AIST and Tokyo-Tech since 1998. A number of M-TRAN modules can form
The M-TRAN system can change its 3-D structure and its motion in order to adapt itself to the environment. In small sized configuration, it walks in a form of legged robot, then metamorphoses into a snake-like robot to enter narrow spaces. A large structure can gradually change its configuration to make a flow-like motion, climb a step by transporting modules one by one, and produce a tower structure to look down. It can also generate multiple walkers. Possible applications of the M-TRAN are autonomous exploration under unknown environment such as planetary explorations, or search and rescue operation in disaster areas.
|Search and rescue||Inspection||Unmanned exploration|
The design of M-TRAN has the advantages of both two types of modular robots, lattice type and chain (linear) type. This hybrid design, unique 3-D shape of the block parts, and parallel joint axes are all keys to realize a flexible self-reconfigurable robotic system.
An M-TRAN module is composed of two blocks (1/2 cubic & 1/2 cylindrical) and a link (Fig.1). Each of the three flat surfaces of each block can mechanically connect and couple with a surface of another module. All the connection surfaces have their gender and an active (male) surface can couple with a passive (female) surface (Fig. 1) in four possible relative orientations (Fig. 2). The connection is controlled by the module itself.
Fig. 1 M-TRAN module
Fig. 2 Varieties of two module connection
Lattice type feature: Each block rotates about its axis by the joint motor. If all the joint angles are either 0, 90 or -90 degrees, all the blocks align on the regular cubic lattice (Fig. 3). Lattice structure is useful for self-reconfiguration.
Chain type feature: When all the joint angles are controlled synchronously, the whole body realizes a flexible robotic motion (Fig. 4).
Each M-TRAN module has its own controller and intelligence, and all the controllers work cooperatively forming a Distributed Autonomous System as a whole.
|Fig. 3 Lattice structure||Fig. 4 Robotic motions|
Modular robot: A robotic system, in which variour robots are constructed by building blocks called modules. Modules can be of unique design (homogeneous modular system), or of various types (heterogeneous). M-TRAN is a homogeneous modular robotic system.
Self-reconfiguration: If the mechanical connection of modules is controlled by modules themselves, the total structure metamorphoses (or reconfigures) by several processes of disconnection, motion and reconnection.
Distributed Autonomous System: A system made of many autonomous sub-systems, which interact or communicate and cooperate with each others to make the total system self-organize.
Simulation & Experiments