On the Design and Construction of Direct-Drive Robots

1990 ◽  
Vol 112 (2) ◽  
pp. 197-201 ◽  
Author(s):  
H. Kazerooni ◽  
S. Kim
Keyword(s):  
Dynamic Behavior ◽  
Direct Drive ◽  
Parallel Processor ◽  
Compliance Control ◽  
Synchronous Motors ◽  
High Torque ◽  
Fine Manipulation ◽  
Four Bar Linkage ◽  
Speed Accuracy ◽  
Accuracy And Repeatability

In this research, a statically-balanced direct-drive manipulator is designed and constructed to achieve improved dynamic behavior for compliance control [10, 11, 12]. The manipulator mechanism, incorporating a four-bar linkage, is designed so that its functional parts are balanced in all positions without the addition of counterweights. The motors are never loaded by gravity. As a result, smaller motors with less torque can be used to achieve higher speed, accuracy, and repeatability in fine manipulation tasks. The robot is powered by high-torque AC synchronous motors. The mechanism is comprised of graphite-epoxy and AA7075T6 aluminum materials. The manipulator is controlled by a parallel processor computer.

Statically balanced direct drive manipulator

Robotica ◽  
1989 ◽  
Vol 7 (2) ◽  
pp. 143-149 ◽  
Author(s):  
H. Kazerooni
Keyword(s):  
Control Law ◽  
Direct Drive ◽  
University Of Minnesota ◽  
Tracking Accuracy ◽  
Synchronous Motors ◽  
Gravity Forces ◽  
Dynamic Tracking ◽  
Yield Acceleration ◽  
The University ◽  
Four Bar Linkage

SUMMARYA practical architecture, using a four-bar-linkage, is considered for the University of Minnesota direct drive rotot. This statically-balanced direct drive robot has been constructed for stability analysis of the robot in constrained maneuvers.2–6 As a result of the elimination of the gravity forces (without any counter weights), smaller actuators and consequently smaller amplifiers were chosen. The motors yield acceleration of 5 g at the robot end point without overheating. High torque, low speed, brush-less AC synchronous motors are used to power the robot. Graphite-epoxy composite material is used for the construction of the robot links. A 4-node parallel processor has been used to control the robot. The dynamic tracking accuracy-with the feedforward torque method as a control law- has been derived experimentally.

Analysis of a Novel Multi-Tooth Flux-Switching PM Brushless AC Machine for High Torque Direct-Drive Applications

2008 ◽  
Vol 44 (11) ◽  
pp. 4313-4316 ◽  
Author(s):  
Z.Q. Zhu ◽  
J.T. Chen ◽  
Y. Pang ◽  
D. Howe ◽  
S. Iwasaki ◽  
...  
Keyword(s):  
Direct Drive ◽  
High Torque

Comparison of Motion Characteristics of High Performance CNC Rotary Tables

2010 ◽  
Author(s):  
Muditha K. M. Dassanayake ◽  
Masaomi Tsutsumi
Keyword(s):  
High Performance ◽  
Closed Loop ◽  
Friction Torque ◽  
Step Response ◽  
Rotary Table ◽  
Direct Drive ◽  
Drive Motor ◽  
Fluctuation Frequency ◽  
Motion Characteristics ◽  
Accuracy And Repeatability

In this paper, the motion performances of the two rotary tables which are driven by roller gear cam and direct drive motor are measured and compared. The table with roller gear cam was controlled in semi-closed loop and full-closed loop methods while the other was controlled only in full-closed loop method. In the measurements, the positioning accuracy and repeatability, rotational fluctuation, frequency response, step response and etc of the systems were measured. All these tests were carried out without any kind of compensation methods such as pitch error or cogging torque compensation etc. Three rotary encoders for rotary table with roller gear cam and one rotary encoder for rotary table with direct drive motor were used for measurements. Furthermore, the simulations were carried out by mathematical models and the results were compared with measured results. The comparison shows that the measured and simulated results have a good agreement. From the simulation results, the friction torque was identified and also compared. The results imply that though both the tables show high performances, the performances of the rotary table driven by roller gear cam are comparatively higher than that of rotary table driven by direct drive motor.

A New Method for Determining the Effects of Structural Flexibility on the Dynamic Behavior of High Speed Mechanisms

1999 ◽  
Author(s):  
L. Yuan ◽  
J. Rastegar
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
New Method ◽  
Structural Flexibility ◽  
Structural Elements ◽  
Dynamics Modeling ◽  
Linkage Mechanism ◽  
Active Materials ◽  
Response Characteristics ◽  
Four Bar Linkage

Abstract A new method for the analysis of the effects of structural flexibility on the dynamic behavior of mechanical systems is presented. The developed method is in most part based on “tracing” the “propagation” of the effects of the high frequency motion requirements on the dynamic response characteristics of machines with structural flexibilities, particularly those with closed-loop kinematic structures. The method considers the “filtering” action of structural elements with flexibility. Such filtering of higher frequency motions is shown to have a predictable effect on the steady state motion of such mechanical system. The main advantage of the developed method is that the effects of such flexibilities can be determined without the need to perform the usual dynamics modeling and computer simulations. The method is shown to be very simple and readily implementable. The method is applied to a four-bar linkage mechanism with a longitudinally flexible coupler link. The obtained results are shown to be highly accurate as compared to those obtained by computer simulation. The application of the method to systematic design of machines with structural flexibility for high speed and precision operation, optimal integration of smart (active) materials into the structure of such machines, and some related issues are discussed.

Compliance Control of Direct Drive Manipulator Using Ultrasonic Motor

1995 ◽  
pp. 125-130 ◽  
Author(s):  
A. Kato ◽  
N. Kondo ◽  
H. Narita ◽  
K. Ito ◽  
Z. W. Luo
Keyword(s):  
Ultrasonic Motor ◽  
Direct Drive ◽  
Compliance Control

Design of a Kind of Novel Limited-Angle Brushless Torque Motor

2012 ◽  
Vol 468-471 ◽  
pp. 871-874 ◽  
Author(s):  
Zhan Ting Fan ◽  
Wei Guo Liu ◽  
An Chao He
Keyword(s):  
Automatic Control ◽  
High Reliability ◽  
Basic Structure ◽  
Electromagnetic Torque ◽  
Test Results ◽  
Direct Drive ◽  
Electrical Drive ◽  
Welding Equipment ◽  
High Torque ◽  
Limited Angle

A kind of 5Nm prototype LABLTM (Limited-Angle Brushless Torque Motor) is presented and designed. The basic structure of the motor is deliberated. The method of calculating the electromagnetic torque is provided. The Magnet software is used to optimize some important parameters of the motor. The prototype is fabricated. The test results of the prototype indicate that the LABLTM, with high torque and high reliability, does meet the requirements of direct drive actuator of precision welding equipment. It has a promising future in automatic control, electrical drive, etc.

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