Hirofumi Miura

Dynamic Walk of a Biped

The authors have developed five kinds of biped locomotive robots so far. They are named BIPER-1, 2, 3, 4, and 5. All of them are statically unstable but can perform a dynamically stable walk with suitable control. BIPER-1 and BIPER-2 walk only sideways. BIPER-3 is a stilt-type robot whose foot contacts occur at a point and who can walk sideways, back ward, and forward. BIPER-4s legs have the same degrees of freedom as human legs. BIPER-5 is similar to BIPER-3, but in the case of BIPER-5 all apparatus, such as the computer, are mounted on it. This paper deals with the control theory used for BIPER-3 and BIPER-4. In both cases, basically the same control method is applied. The most important point is that the mo tion of either robot during the single-leg support phase can be approximated by the motion of an inverted pendulum. Ac cordingly, in this paper, dynamic walk is considered to be a series of inverted-pendulum motions with appropriate condi tions of connection.

Insect-model based microrobot with elastic hinges

This paper describes the new concept of making a microrobot based upon insects and its implementation using rigid plates and elastic hinges. One unique feature of an insects structure is its deformable external skeleton, to which wings and legs are attached, forming a closed-loop mechanism. Frictionless deformation of elastic elements, instead of conventional rotational joints, allows for efficient actuation in the microscale. We propose three-dimensional micromechanisms based on an external skeleton and have fabricated several examples using polysilicon plates and polyimide hinges. By folding the polysilicon plates along the polyimide hinges just like paper, 3D structures can be constructed on silicon wafers. These structures can be easily actuated by electrostatic force. Closed-loop flapping mechanisms have been fabricated and electrostatically actuated to demonstrate the motion of the external skeleton system. Resonant vibration was observed in a frequency range of around 10 kHz. Actuation using electrostatic induction is also considered. >

Creation of an insect-based microrobot with an external skeleton and elastic joints

The concept of making a microrobot with an external skeleton, like an insect, and its implementation using rigid plates and elastic joints is described. A large-scale model consisting of plastic plates and solenoids is shown to demonstrate this motion. Several microsized models using polysilicon plates and polyimide joints have been built on silicon wafers. By folding these at the joints, just like paper, three-dimensional structures can be constructed. These structures can be actuated by electrostatic force.<<ETX>>

Microrobot actuated by a vibration energy field

Abstract A vibration energy field generated by a piezoelectric vibrator can supply a microrobot with power without using wires, by exciting resonant actuators mechanically. Furthermore, this energy field implicitly contains control signals that make it possible to activate actuators selectively. A microrobot measuring 1.5 mm×0.7 mm has been fabricated using silicon micromachining technology and a folding process to make three-dimensional structures. The microrobot is modelled as a damped three-degree-of-freedom system driven by displacement excitation. The microrobots design is determined from simulation results based on this model.

CMOS drivable electrostatic microactuator with large deflection

A new type of low voltage (11.8 V), large deflection (245 /spl mu/m), electrostatic microactuator has been developed. Its performance was achieved by using several cantilevers connected in series and bending continuously. All of the cantilevers require the same low voltage to bend as one single cantilever does. Each cantilever has a straight beam section and a curved beam section. Experiments show that the length of both beam sections is important in order to decrease the driving voltage. The actuator has a large hysteresis and has a critical voltage which is required to drive it. This required voltage is low enough to allow a CMOS device to drive the actuator. Moreover, a small solar cell panel was able to supply the actuator with the necessary power to drive it.

Water strider robots with microfabricated hydrophobic legs

This paper discusses biomimetic water strider robots that have microfabricated hydrophobic legs. Various kinds of supporting legs with hydrophobic microstructures on their surfaces were developed using MEMS (micro electromechanical systems) techniques. The lift and pull-off forces of these supporting legs were analyzed theoretically and then measured. The experimental results were in good agreement with the calculations. Two different mechanisms for autonomous water strider robots were developed. One robot with twelve microfabricated legs driven by a vibration motor successfully moved on a water surface and also made left/right turns by exploiting differences in the resonant frequencies of the legs. The other robot, with six microstructured legs, moved on water through elliptical motion of its middle legs, which is similar to the motion of actual water striders.

Micromanipulation using magnetic field

Magnetic force is useful for manipulating objects without contact. We propose a method of micromanipulation using this force. The concept is based upon linkage-free end-effectors and different from the concept of serial-link manipulators. Multiple cylindrical permanent magnets work as end-effectors. The permanent magnets on the stage, above an arrangement of solenoids, manipulate objects by pushing. Furthermore, 3D manipulation can be achieved as a link mechanism is used. A prototype of the manipulator has been fabricated. The manipulation field measures 4.5 cm/spl times/4.5 cm and consists of 6/spl times/6 solenoids. The magnets are 6 mm in diameter. The ability of a magnet to follow a control signal and the force for pushing an object have been evaluated. Furthermore, a prototype of the link mechanism has been fabricated. The vertical force for pushing down and pulling up an object have also been evaluated.

Synthesis of pheromone-oriented emergent behavior of a silkworm moth

The purpose of this research is to clarify moth emergent behavior by synthesis with currently developed tools, including living sensors and recurrent neural networks. The antennae on a silkworm moth are very sensitive compared with artificial gas sensors. These living antennae can be used as living gas sensors that can detect pheromone molecules with high sensitivity. Recurrent artificial neural networks are applied for controlling the pheromone tracing. As a result, a mobile robot with living antennae can follow a stream of pheromone like a male silkworm moth. The small numbers of neurons can generate moth-like behavior, including casting, and turning while interacting with the environment.

Two-dimensional micro-self-assembly using the surface tension of water

Several self-assembling microstructures have been fabricated, and approximately 100 units floating on the surface of water were self-assembled two-dimensionally. The basic assembly units are 400 /spl mu/m large, and consist of both polyimide and polysilicon thin films. Surface tension was used in this system as the bonding force. The surface tension is the local interaction between the units, and is dominant in the microscale. Each unit was bonded selectively by employing the following characteristics of the surface tension: 1) objects located at equal heights are attracted to each other, 2) large attractive forces act on sharp parts, and 3) objects located at different heights are mutually repulsed. The curling-up property of the thin films was used to obtain the different heights. Self-assembling behaviour was also predicted by using a rate equation.

Microrobot locomotion in a mechanical vibration field

A mechanical vibration field generated by a piezoelectric vibrator can supply a microrobot with power without using wires, by exciting resonant actuators mechanically. Furthermore, this energy field implicity contains control signals that make it possible to activate actuators selectively. A microrobot measuring 1.5 mmx0.7 mm was fabricated using silicon micromachining technology and a folding process to make three-dimensional structures. The microrobot is modeled as a damped, 3 d.o.f. system driven by displacement excitation. The microrobots design was determined from simulation results based on this model. The fastest microrobot walks at a velocity of about 2 mm/s on the conductive base vibrating with an amplitude of 1 μm. The conductivity of the base has a great influence on the microrobot velocity, because electrostatic force between the microrobot and the base prevents the microrobot from moving rapidly.