Digital microrobotics based on bistable modules : Design of compliant bistable structures.

International audienceIn the context of micromanipulation and microassembly, we propose in this paper a new type of microrobot based on bistable modules : digital microrobots. This concept consists in building a monolithic microrobot using microfabrication technology without anay assembly. It gets over the difficulties of traditional microrobots : non linear control, integration of sensors, noise, etc... Each module contains a bistable structure and actuators. No external energy input is needed to maintain the structure in a stable position. This opens a paradigm in the microrobotics field allowing the design of various kinematics adapted to the microworld

Design of Massive Actuators For 3D Robot Manipulators

In this paper, a novel parallel manipulator with discrete control system is developed. An efficient method such as Inverse Static Analysis (ISA) is employed to determine the state of each actuator on parallel manipulator when the position or force of manipulator is already known. The designing a parallel manipulator with 16 actuators which are controlled discretely is a must because the mechanism will use artificial methods in dealing with the ISA problem. In this approach, mathematical model is not required. The research method used simulation software and hardware testing with the case of parallel manipulator with 16 actuators. Simulations with typical desired force inputs are presented and a good performance of the mechanism is obtained. The results showed that the parallel manipulator has the Root Mean Squared Error (RMSE) has less than 3% and can be used for artificial intelligence implementation

Microfabricated bistable module for digital microrobotics.

International audienceHigh precision microrobots are needed more and more to perform micro/nanomanipulation and microassembly tasks in various environments like microrobotic stations, electronic microscopes (SEM, TEM), etc. Current microrobots are based on the use of smart materials to perform proportional or incremental actuation. To avoid the main drawbacks of these microrobots (non linearities, integration of sensors, robust control, energy consumption, sensitivity to noise), we propose a new type of microrobots, called digital microrobots, based on microfabricated bistable modules. The study presented in this paper is dedicated to the microfabricated bistable modules, notably the structure and the actuators design and characterization. The results open a new paradigm in the field of microrobotics leading to open loop control and the design of various kinematics adapted to the microworld. Moreover, no external energy is required to maintain the microrobot in its position

Reduction of dimensionality of a cellular actuator array for driving a robotic hand

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (p. 89-93).In an attempt to explore an alternative to today's robot actuators, a new approach to artificial muscle actuator design and control is presented. The objective of this research is to coordinate the multitude of artificial muscle actuator axes for a large DOF (degree of freedom) robotic system based on dimensionality reduction. An array of SMA actuators is segmented into many independently controlled, spatially discrete volumes, each contributing a small displacement to create a large motion. Segmented Binary Control is proposed where each segment is controlled in an on-off manner, creating a stepper-motor like actuator. This overcomes hysteresis and other nonlinearities of the actuator material. The segmented cellular architecture of SMA wires is extended to a multi-axis actuator array by arranging the segments in a two-dimensional array. The multi-axis control is streamlined and coordinated using a grouping of segments called C-segments in order to activate multiple links of a robot mechanism in a coordinated manner. This allows control of large DOF with a small number of controls. The proposed approach is inspired by the segmented architecture of biological muscles and synergies, a strategy of grouping output variables to simplify the control of large number of muscles. Data from various hand postures are collected using data glove and used in creating the C-segment design that is capable of performing the given postures. A lightweight Robotic Hand with 16 DOF is built using shape memory alloy actuators. This hand weighs less than 1kg including 32 SMA actuators and control circuitry. Eight C-segments that are ON-off controlled are used to create sixteen given postures. In the future, this approach can be applied to applications where the control signal is inherently limited due to limited amount of information that can be extracted or transferred to the robot, such as brain machine interface and tele-operation.by Kyu-Jin Cho.Ph.D