Development of an Active End Effector for Cable Robot Calibration

2021 ◽  
pp. 336-347
Author(s):  
Pauline Marie Nüsse ◽  
Marcus Hamann ◽  
David Lukas Winter ◽  
Christoph Ament
Keyword(s):  
Robot Calibration ◽  
End Effector ◽  
Cable Robot

Experimental results for the flexible joint cable-suspended manipulator of ICaSbot

Robotica ◽  
2013 ◽  
Vol 31 (6) ◽  
pp. 887-904 ◽  
Author(s):  
M. H. Korayem ◽  
M. Bamdad ◽  
H. Tourajizadeh ◽  
A. H. Korayem ◽  
R. M. Zehtab ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Experimental Tests ◽  
Parallel Robot ◽  
Joint Space ◽  
End Effector ◽  
Flexible Joint ◽  
Cable Robot ◽  
Six Dof ◽  
And Control ◽  
Computed Torque

SUMMARYIn this paper, design, dynamic, and control of the motors of a spatial cable robot are presented considering flexibility of the joints. End-effector control in order to control all six spatial degrees of freedom (DOFs) of the system and motor control in order to control the joints flexibility are proposed here. Corresponding programing of its operation is done by formulating the kinematics and dynamics and also control of the robot. Considering the existence of gearboxes, flexibility of the joints is modeled in the feed-forward term of its controller to achieve better accuracy. A two sequential closed-loop strategy consisting of proportional derivative (PD) for linear actuators in joint space and computed torque method for nonlinear end-effector in Cartesian space is presented for further accuracy. Flexibility is estimated using modeling and simulation by MATLAB and SimDesigner. A prototype has been built and experimental tests have been done to verify the efficiency of the proposed modeling and controller as well as the effect of flexibility of the joints. The ICaSbot (IUST Cable-Suspended robot) is an under-constrained six-DOF parallel robot actuated by the aid of six suspended cables. An experimental test is conducted for the manufactured flexible joint cable robot of ICaSbot and the outputs of sensors are compared with simulation. The efficiency of the proposed schemes is demonstrated.

A Dual-Stage Planar Cable Robot: Dynamic Modeling and Design of A Robust Controller with Positive Inputs

2004 ◽  
Vol 127 (4) ◽  
pp. 612-620 ◽  
Author(s):  
So-Ryeok Oh ◽  
Kalyan Mankala ◽  
Sunil K. Agrawal ◽  
James S. Albus
Keyword(s):  
Degrees Of Freedom ◽  
Robust Controller ◽  
Two Stage ◽  
End Effector ◽  
Six Degrees Of Freedom ◽  
Cable Robot ◽  
Unknown Disturbances ◽  
Dual Stage ◽  
Loading And Unloading ◽  
Skin To Skin

Cable robots have potential usage for loading and unloading of cargo in shipping industries. A novel six-degrees-of-freedom two-stage cable robot has been proposed by NIST for skin-to-skin transfer of cargo. In this paper, we look at a planar version of this two-stage cable robot. The disturbance motion from the sea is considered while modeling the dynamics of robot. The problem of robust control of the end-effector in the presence of unknown disturbances, along with maintaining positive tensions in the cables, is tackled using redundancy of cables in the system. Simulation results show the effectiveness of the control strategy.

scholarly journals A two-stage calibration method for industrial robots with joint and drive flexibilities

2015 ◽  
Vol 6 (2) ◽  
pp. 191-201 ◽  
Author(s):  
M. Neubauer ◽  
H. Gattringer ◽  
A. Müller ◽  
A. Steinhauser ◽  
W. Höbarth
Keyword(s):  
Transfer Functions ◽  
Geometric Model ◽  
Maximum Error ◽  
Industrial Robots ◽  
Robot Calibration ◽  
Two Stage ◽  
End Effector ◽  
The Real ◽  
Frequency Responses ◽  
Real Robot

Abstract. Dealing with robot calibration the neglection of joint and drive flexibilities limit the achievable positioning accuracy significantly. This problem is addressed in this paper. A two stage procedure is presented where elastic deflections are considered for the calculation of the geometric parameters. In the first stage, the unknown stiffness and damping parameters are identified. To this end the model based transfer functions of the linearized system are fitted to captured frequency responses of the real robot. The real frequency responses are determined by exciting the system with periodic multisine signals in the motor torques. In the second stage, the identified elasticity parameters in combination with the measurements of the motor positions are used to compute the real robot pose. On the basis of the estimated pose the geometric calibration is performed and the error between the estimated end-effector position and the real position measured with an external sensor (laser-tracker) is minimized. In the geometric model, joint offsets, axes misalignment, length errors and gear backlash are considered and identified. Experimental results are presented, where a maximum end-effector error (accuracy) of 0.32 mm and for 90 % of the poses a maximum error of 0.23 mm was determined (Stäubli TX90L).

scholarly journals A Novel Optimal Design of Measurement Configurations in Robot Calibration

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Qingxuan Jia ◽  
Shiwei Wang ◽  
Gang Chen ◽  
Lei Wang ◽  
Hanxu Sun
Keyword(s):  
Optimal Design ◽  
Pose Estimation ◽  
Kinematic Parameter ◽  
Critical Importance ◽  
Kinematic Parameters ◽  
Robot Calibration ◽  
End Effector ◽  
Proposed Model ◽  
Observability Index ◽  
Sample Data

Robot calibration highly depends on redundant measurement configurations to collect enough sample data for higher accuracy, but excessive measurements seem to be uneconomical and time-consuming. Thus lots of observability indexes to evaluate the goodness of the measurement configurations have been proposed. However, in some circumstances, it is of critical importance to obtain accurate kinematic parameters and estimate the end-effector pose precisely at the same time. Obviously one single observability index can hardly meet this need yet. Accordingly, after analyzing the essential constrains of robot calibration and the influence of measurement configurations on the observability indexes, an optimization model with two observability indexes to be taken into consideration is proposed in this paper, and then the existing DETMAX algorithm is modified to seek optimal design of measurement configurations, by adopting a set-constructing method and a set-shrinking method. Much better results have been obtained by simulation study, which implies that the proposed model and the modified DETMAX algorithm perform well in both kinematic parameter identification and pose estimation of the end-effector of the robot.

PRECISE POSE MEASUREMENT WITH SINGLE CAMERA CALIBRATION FOR PLANAR PARALLEL MANIPULATORS

2011 ◽  
Vol 35 (2) ◽  
pp. 201-213 ◽  
Author(s):  
Richard Neumayr ◽  
Paul Zsombor-Murray ◽  
Paul O’Leary
Keyword(s):  
Low Cost ◽  
Principal Component ◽  
Image Plane ◽  
Parallel Manipulators ◽  
Robot Calibration ◽  
End Effector ◽  
Light Emitting ◽  
Moving Plane ◽  
Processing Techniques ◽  
Planar Parallel Manipulators

Pose measurement is an important tool for robot calibration. This paper describes the development and implementation of a technique of camera-aided pose measurement, tested on the Planar Double Triangular Parallel Manipulator (PDTPM). A stationary camera is used to take photos of the End Effector (EE) where a certain array of Light Emitting Diodes (LED) is mounted on. Using various image processing techniques, the coordinates of the LEDs are registered in the image in order to derive the projection matrix that maps any point of the image plane to world coordinates in the EE moving plane. This homography is computed with a method where the vanishing line is treated as the principal component. This estimate is more robust and faster than the Direct Linear Transformation (DLT) method. It was shown that poses could be quickly registered at submillimetre precision notwithstanding inexpensive, relatively low resolution optics. The measurement system is easy to setup, portable, accurate, low cost and it is believed to be a valuable tool.

A Dual Stage Planar Cable Robot: Dynamic Modeling and Design of a Robust Controller With Positive Inputs

2004 ◽  
Author(s):  
So-Ryeok Oh ◽  
Kalyan Mankala ◽  
Sunil K. Agrawal ◽  
James S. Albus
Keyword(s):  
Robust Controller ◽  
Two Stage ◽  
End Effector ◽  
Cable Robot ◽  
Unknown Disturbances ◽  
Dual Stage ◽  
Loading And Unloading ◽  
Simulation Results ◽  
Six Degree Of Freedom ◽  
Skin To Skin

Cable robots have been extensively used for loading and unloading of cargo in shipping industries. A novel six-degree of freedom two-stage cable robot has been proposed by NIST for skin-to-skin transfer of cargo. In this paper, we look at a planar version of this two-stage cable robot. The disturbance motion from the sea is considered while modeling the dynamics of robot. The problem of robust control of the end-effector in the presence of unknown disturbances, along with maintaining positive tensions in the cables, is tackled by using the idea of redundancy. Simulation results show the effectiveness of the control strategy.

Vibration Analysis of Cable-Driven Parallel Robot for Asymmetric Tension and Position

2016 ◽  
Author(s):  
Hyundong Do ◽  
Kyoung-Su Park
Keyword(s):  
Vibration Analysis ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
The Other ◽  
End Effector ◽  
Cable Robot

Cable-driven parallel robot (CDPR) consists of three parts: an end-effector, a number of cables and actuators. CDPRs are a type of parallel manipulators which the end-effector is supported in parallel by cables. CDPRs have two types. One is the fully-constrained type, and the other is the under constrained type. Fully-constrained type cable robot require n+1 wires, where n is the number of freedom to be constrained [1].

Design-to-Workspace Synthesis of a Cable Robot Used in Legs Training Machine

Robotica ◽  
2019 ◽  
Vol 38 (9) ◽  
pp. 1703-1714
Author(s):  
Houssein Lamine ◽  
Lotfi Romdhane ◽  
Houssem Saafi ◽  
Sami Bennour
Keyword(s):  
Dynamic Simulation ◽  
Optimization Algorithm ◽  
Interval Analysis ◽  
Gait Training ◽  
Design Approach ◽  
End Effector ◽  
Design Task ◽  
Cable Robot ◽  
Analysis Tools ◽  
External Loads

SUMMARYThis paper deals with a continuous design task of a planar cable robot used in a gait training machine called the cable-driven legs trainer. The design of cable robots requires satisfying two constraints, that is, tensions in the cables must remain non-negative, and cable interferences should be avoided. The carried design approach is based on interval analysis, which is one of the most efficient methods to obtain certified results. The constraints of non-negative tensions and cable to end-effector interference are solved using interval analysis tools. By means of a dynamic simulation, the reached workspace and the produced wrenches of the cable robot are evaluated as a set of interval vectors. An optimization algorithm is then designed to optimize the cable robot structure for the gait training machine. The robot is designed to produce non-negative tensions in the cables and to avoid collision at all times within the desired workspace and under the required external loads.

Robot performance measurement and calibration using a 3D computer vision system

Robotica ◽  
1995 ◽  
Vol 13 (4) ◽  
pp. 327-337 ◽  
Author(s):  
B. Preising ◽  
T. C. Hisa
Keyword(s):  
Computer Vision ◽  
Robot Control ◽  
Vision System ◽  
Computer Vision System ◽  
Robot Calibration ◽  
End Effector ◽  
Tolerance Level ◽  
Cartesian Space ◽  
3D Computer Vision ◽  
Robot Performance

SummaryPresent day robot systems are manufactured to perform within industry accepted tolerances. However, to use such systems for tasks requiring high precision, various methods of robot calibration are generally required. These procedures can improve the accuracy of a robot within a small volume of the robot's workspace. The objective of this paper is to demonstrate the use of a single camera 3D computer vision system as a position sensor in order to perform robot calibration. A vision feedback scheme, termed Vision-guided Robot Control (VRC), is described which can improve the accuracy of a robot in an on-line iterative manner. This system demonstrates the advantage that can be achieved by a Cartesian space robot control scheme when end effector position/orientation are actually sensed instead ofcalculated from the kinematic equations. The degree of accuracy is determined by setting a tolerance level for each of the six robot Cartesian space coordinates. In general, a small tolerance level requires a large number of iterations in order to position the end effector, and a large tolerance level requires fewer iterations. The viability of using a vision system for robot calibration is demonstrated by experimentally showing that the accuracy of a robot can be drastically improved. In addition, the vision system can also be used to determine the repeatability and accuracy of a robot in a simple, efficient, and quick manner. Experimental work with an IBM Electric Drive Robot (EDR) and the proposed vision system produced a 97 and a 145 fold improvement in the position and orientation accuracy of the robot, respectively.

A Cable-Suspended Robot With a Novel Cable Based End Effector

2010 ◽  
Author(s):  
Omid Saber ◽  
Soroush Abyaneh ◽  
Hassan Zohoor
Keyword(s):  
Degrees Of Freedom ◽  
Point Mass ◽  
Cable Tension ◽  
End Effector ◽  
Spatial Point ◽  
Cable Robot ◽  
Moment Resisting ◽  
The Moment ◽  
Robot Workspace

Object handling is one of the most important applications of cable-suspended robots, which can be obtained by use of a gripper as its end-effector. In this paper, a novel cable-driven multi-finger gripper assembled on a cable-suspended robot has been presented. Using lock/unlock mechanisms, the under-actuated finger mechanism has been designed to have a human like motion. A cable-suspended robot structure with 3 position degrees of freedom is also proposed by employing active/passive cables in such a way that makes it capable of resisting external moments, while it may be simplified to a spatial point-mass cable robot during positioning operation. Furthermore, the robot workspace has been investigated and by considering both lower and upper cable tension limits, a formulation for obtaining the force-feasible workspace is presented and the influence of the minimum tension limit on the workspace is discussed. Finally the moment-resisting capability of the proposed robot has been investigated and by considering several cases, its moment-resisting region is compared to an analogous robot.

Sign in / Sign up

Export Citation Format

Share Document