Shoichi Iikura

Development of flexible microactuator and its applications to robotic mechanisms

A flexible microactuator (FMA) driven by an electropneumatic (or electrohydraulic) system has been developed. The FMA has three degrees of freedom, pitch, yaw, and stretch, and these are suitable movements for miniature robotic mechanisms such as fingers, arms, or legs. The construction is of fiber-reinforced rubber, and the mechanism is very simple. Gentle miniature robots with no conventional links can be designed using this design. The FMAs basic characteristics and its applications to certain robot mechanisms are presented. Serially connected FMAs act as a miniature robot manipulator. The kinematics and control algorithm for this type of robot are presented. FMAs combined in parallel act as a multifingered robot hand, with each FMA representing a finger. An algorithm for the cooperative control of such FMAs, the stable region for holding, and its performance are presented.<<ETX>>

Applying a flexible microactuator to robotic mechanisms

A flexible microactuator (FMA) driven by an electropneumatic (or electrohydraulic) system has been developed. It has three degrees of freedom-pitch, yaw, and stretch-making it suitable for robotic mechanisms such as fingers, arms, or legs. It is made of fiber-reinforced rubber, and the mechanism is very simple, enabling miniature robots without conventional link mechanisms to be designed. Serially connected FMAs act as a miniature robot manipulator. The kinematics and control algorithm for this type of robot are presented. FMAs combined in parallel act as a multifingered robot hand, with each FMA representing a finger. An algorithm for the cooperative control for such FMAs, the stable region for holding, and its performance have been developed.<<ETX>>

Flexible microactuator for miniature robots

A new type of flexible microactuator (FMA) has been developed for use in miniature robots. They are constructed using fiber-reinforced rubber and are actuated by an electropneumatic or electrohydraulic system. These microactuators have many degrees of freedom (including pitch, yaw, and stretch), making them suitable for robotic mechanisms such as arms, legs, or fingers. Pliant miniature robots can be created by combining FMAs. One example is a robot arm a few millimeters in diameter with seven degrees of freedom. The basic characteristics of the FMAs have been analyzed theoretically and experimentally. It is noted that, since the statistics and dynamics are predicted easily, FMAs can be designed efficiently.<<ETX>>

Electrostatic linear microactuator mechanism for focusing a CCD camera

A newly developed linear electrostatic microactuator mechanism employing a vibrating motion is described. In order to achieve a miniature charge coupled device (CCD) camera with autofocusing and zoom functions, we developed an electrostatic linear microactuator with a large movement range. In miniature CCD cameras, extremely thin electrostatic actuators are needed because the space available for the focusing mechanism is reduced. The moving part (slider) of this actuator is sandwiched between fixed electrodes (stator), is alternately attached and detached to these fixed electrodes, and actuates linearly on a macroscopic level. The fundamental feasibility of this vibrating motion mechanism was first confirmed in experiments. This actuator was then applied to the focusing mechanism of a miniature CCD camera. A microlens was fitted inside the slider and it was possible to adjust the focus by moving the slider (with microlens). The size of the prototype for the focusing mechanism is 3.6/spl times/4.6/spl times/8.0 mm, and a 2-mm movement range is achieved. The minimum driving voltage is 60 V and the maximum velocity is 1.0 min/s.

Active Vibration Control for Flexible Space Environment Use Manipulators

A new dynamic control system for flexible space environment use manipulators has been developed from the practical viewpoint. The key concept in the proposed method is that the local position and torque PD feedback loop at each joint should be used for position and structural vibration control. First, the authors derived manipulator dynamics, and then feedback control was developed, using an appropriate potential function. Secondly, an experimental setup using an air suspended SCARA flexible manipulator is described. The effectiveness of this method has been verified by experimental results, adapting it to automatic payload handling.

Vibration control for two-link flexible manipulator using a wrist force sensor.

This paper reports on the vibration control of a flexible space manipulator in which the tip deflection of each flexible link is fed back in a closed control system. A simple dynamic model is derived using the static deflection model to derive the system dynamics equations of a flexible manipulator. A force/torque sensor incorporated in the manipulators wrist is proposed as a new type of sensors to estimate the deflection. To investigate the effectiveness of this control method, a two-link flexible SCARA manipulator system was constructed. This manipulator was 1.5 m long and was floating on a base-plate using air bearings capable of handling a 40kg payload. The experimental results showed that the deflection feedback realized the same effect on the vibration control as the general method of strain gauge output feedback.