Actuators for a space manipulator

The robotic manipulator can be decomposed into distinct subsytems. One particular area of interest of mechanical subsystems is electromechanical actuators (or drives). A drive is defined as a motor with an appropriate transmission. An overview is given of existing, as well as state-of-the-art drive systems. The scope is limited to space applications. A design philosophy and adequate requirements are the initial steps in designing a space-qualified actuator. The focus is on the d-c motor in conjunction with several types of transmissions (harmonic, tendon, traction, and gear systems). The various transmissions will be evaluated and key performance parameters will be addressed in detail. Included in the assessment is a shuttle RMS joint and a MSFC drive of the Prototype Manipulator Arm. Compound joints are also investigated. Space imposes a set of requirements for designing a high-performance drive assembly. Its inaccessibility and cryogenic conditions warrant special considerations. Some guidelines concerning these conditions are present. The goal is to gain a better understanding in designing a space actuator

Selection of systems to perform extravehicular activities, man and manipulator. Volume 2 - Final report

Technologies for EVA and remote manipulation systems - handbook for systems designer

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

Multi-Segment Parallel Continuum Manipulator

Continuum manipulators are a type of robot arm that resemble biological tentacles and trunks. They have a flexible and compliant structure, which may allow them to out-perform rigid-link designs in cluttered workspaces or in environments that contain people. While most continuum manipulators are required to have constant curvature along the length of each segment, a new design known as a parallel continuum manipulator removes this restriction and inherits some properties of parallel rigid-link robots such as greater stability, precision, strength, and maneuverability. Until now, only single segment forms of these manipulators have been created. This project expands this manipulator design concept by creating the first multi-segment parallel continuum manipulator

Operational space control of a lightweight robotic arm actuated by shape memory alloy wires: a comparative study.

This article presents the design and control of a two-link lightweight robotic arm using shape memory alloy wires as actuators. Both a single-wire actuated system and an antagonistic configuration system are tested in open and closed loops. The mathematical model of the shape memory alloy wire, as well as the kinematics and dynamics of the robotic arm, are presented. The operational space control of the robotic arm is performed using a joint space control in the inner loop and closed-loop inverse kinematics in the outer loop. In order to choose the best joint space control approach, a comparative study of four different control approaches (proportional derivative, sliding mode, adaptive, and adaptive sliding mode control) is carried out for the proposed model. From this comparative analysis, the adaptive controller was chosen to perform operational space control. This control helps us to perform accurate positioning of the end-effector of shape memory alloy wire–based robotic arm. The complete operational space control was successfully tested through simulation studies performing position reference tracking in the end-effector space. Through simulation studies, the proposed control solution is successfully verified to control the hysteretic robotic arm

Advanced Mobile Robotics: Volume 3

Mobile robotics is a challenging field with great potential. It covers disciplines including electrical engineering, mechanical engineering, computer science, cognitive science, and social science. It is essential to the design of automated robots, in combination with artificial intelligence, vision, and sensor technologies. Mobile robots are widely used for surveillance, guidance, transportation and entertainment tasks, as well as medical applications. This Special Issue intends to concentrate on recent developments concerning mobile robots and the research surrounding them to enhance studies on the fundamental problems observed in the robots. Various multidisciplinary approaches and integrative contributions including navigation, learning and adaptation, networked system, biologically inspired robots and cognitive methods are welcome contributions to this Special Issue, both from a research and an application perspective

Structural dynamics branch research and accomplishments

Summaries are presented of fiscal year 1989 research highlights from the Structural Dynamics Branch at NASA Lewis Research Center. Highlights from the branch's major work areas include aeroelasticity, vibration control, dynamic systems, and computation structural methods. A listing of the fiscal year 1989 branch publications is given

Solar Tracking Using a Parallel Manipulator Mechanism to Achieve Two-Axis Position Tracking

A novel solar tracker is presented that uses a parallel manipulator for the tracking mechanism instead of a traditional serial manipulator. The motivation is to create a solar tracker that displays the advantages of two-axis tracking systems (e.g., increased exposure to incident radiation, and enabling the use of efficient concentrating solar cells) while addressing some of the disadvantages of current two-axis tracking systems (e.g., the difficulties associated with having actuators mounted to moving elements within the mechanism). The mobility of the proposed parallel manipulator is examined using Grübler’s Criterion to establish that the manipulator displays the required two degrees of freedom. Additionally, a system of equations is developed for the proposed tracker that can be used for the forward or inverse kinematics analysis. Finally, the workspace of the proposed parallel manipulator-based solar tracker is presented