Robot's hand and expansions in non-integer bases

We study a robot hand model in the framework of the theory of expansions in non-integer bases. We investigate the reachable workspace and we study some configurations enjoying form closure properties.Comment: 22 pages, 10 figure

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

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

Space Frames with Multiple Stable Configurations

This paper is concerned with beamlike spaceframes that include a large number of bistable elements, and exploit the bistability of the elements to obtain structures with multiple stable configurations. By increasing the number of bistable elements, structures with a large number of different configurations can be designed. A particular attraction of this approach is that it produces structures able to maintain their shape without any power being supplied. The first part of this paper focuses on the design and realization of a low-cost snap-through strut, whose two different lengths provide the required bistable feature. A parametric study of the length-change of the strut in relation to the peak force that needs to be applied by the driving actuators is carried out. Bistable struts based on this concept have been made by injection molding nylon. Next, beamlike structures based on different architectures are considered. It is shown that different structural architectures produce structures with workspaces of different size and resolution, when made from an identical number of bistable struts. One particular architecture, with 30 bistable struts and hence over 1 billion different configurations, has been demonstrated

A Fibonacci control system with application to hyper-redundant manipulators

We study a robot snake model based on a discrete linear control system involving Fibonacci sequence and closely related to the theory of expansions in non-integer bases. The present paper includes an investigation of the reachable workspace, a more general analysis of the control system underlying the model, its reachability and local controllability properties and the relation with expansions in non-integer bases and with iterated function systems

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

Concept development for lightweight binary-actuated robotic devices, with application to space systems

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001."June 2001."Includes bibliographical references (leaves 66-71).Exploratory space missions of the future will require robotic systems to lead the way by negotiating and mapping very rough terrain, collecting samples, performing science tasks, and constructing facilities. These robots will need to be adaptable and reconfigurable in order to achieve a wide variety of objectives. Conventional designs using gears, motors, bearings, encoders, and many discrete components will be too complex, heavy, and failure-prone to allow highly-reconfigurable systems to be feasible. This thesis develops new concepts that may potentially enable the design of self-transforming space explorers. The vision of this research is to integrate compliant bistable mechanisms with large numbers of binary-actuated embedded smart materials. Compliant mechanisms are lightweight and robust. Binary actuation is the idea of using an actuator in a discrete on/off manner rather than in a continuous manner. A binary actuator is easy to control and robust, and by using tens or hundreds of binary actuators, one can approximate a continuous system, much like a digital computer can approximate an analog system. The first part of this thesis examines the fundamental planning issues involved with systems having large numbers of binary actuators. The notion of a workspace is described and applied to the optimization of a manipulator design. Methods for solving the forward and inverse kinematics are discussed in the context of this application. These methods are extended to the trajectory and locomotion planning problems. Methods for planning systems of substantial complexity are developed in the context of exploratory space robotics. The second part of this thesis presents experimental demonstrations that examine elements of the concept. The results of several design prototypes are discussed.by Matthew D. Lichter.S.M

Mechanical design for the tactile exploration of constrained internal geometries

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.MIT Institute Archives copy: with CD-ROM; divisional library copy with no CD-ROM.Includes bibliographical references (p. 93-98).Rising world oil prices and advanced oil recovery techniques have made it economically attractive to rehabilitate abandoned oil wells. This requires guiding tools through well junctions where divergent branches leave the main wellbore. The unknown locations and shapes of these junctions must be determined. Harsh down-well conditions prevent the use of ranged sensors. However, robotic tactile exploration using a manipulator is well suited to this problem. This tactile characterization must be done quickly because of the high costs of working on oil wells. Consequently, intelligent tactile exploration algorithms that can characterize a shape using sparse data sets must be developed. This thesis explores the design and system architecture of robotic manipulators for down-well tactile exploration. A design approach minimizing sensing is adopted to produce a system that is mechanically robust and suited to the harsh down-well environment. A feasibility study on down-well tactile exploration manipulators is conducted. This study focuses on the mature robotic technology of link and joint manipulators with zero or low kinematic redundancy. This study produces a field system architecture that specifies a unified combination of control, sensing, kinematic solutions for down-well applications. An experimental system is built to demonstrate the proposed field system architecture and test control and intelligent tactile exploration algorithms. Experimental results to date have indicated acceptability of the proposed field system architecture and have demonstrated the ability to characterize geometry with sparse tactile data.(cont.) Serpentine manipulators implemented using digital mechatronic actuation are also considered. Digital mechatronic devices use actuators with discrete output states and the potential to be mechanically robust and inexpensive. The design of digital mechatronic devices is challenging. Design parameter optimization methods are developed and applied to a design case study of a manipulator in a constrained workspace. This research demonstrates that down-well tactile exploration with a manipulator is feasible. Experimental results show that the proposed field system architecture, a 4 degree-of-freedom anthropomorphic manipulator, can obtain accurate tactile data without using any sensor feedback besides manipulator joint angles.by Daniel Terrance Kettler.S.M

Applications of Artificial Intelligence Control for Parallel Discrete-Manipulators

Parallel Discrete-Manipulators are a special kind of force regulated manipulators which can undergo continuous motions despite being commanded through a large but finite number of states only. Real-time control of such systems requires very fast and efficient methods for solving their inverse static analysis. In this paper, artificial intelligence techniques (AI) are investigated for addressing the inverse static analysis of a planar parallel array featuring ten three-state force actuators and two applications using 3D Massively Parallel Robots (MPRs) with one and two layers. In particular, the research method used simulation software and hardware testing with the case of parallel manipulator with two level discrete pneumatic actuators. Simulations with typical desired displacement inputs are presented and a good performance of the results compared to AI is obtained. The comparison showed that the parallel manipulator has the Root Mean Squared Error (RMSE) has less than 10% and can be used for controlling the ternary states of discrete manipulators via AI