A Simple Two-step Geometric Approach for the Kinematic Calibration of the 3-PRS Parallel Manipulator

Robotica ◽  
2019 ◽  
Vol 37 (5) ◽  
pp. 837-850
Author(s):  
Genliang Chen ◽  
Lingyu Kong ◽  
Qinchuan Li ◽  
Hao Wang
Keyword(s):  
Parameter Identification ◽  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Calibration Method ◽  
Kinematic Parameter ◽  
Geometric Constraints ◽  
Kinematic Calibration ◽  
Kinematic Parameters ◽  
Positioning Accuracy ◽  
Kinematic Parameter Identification

SummaryKinematic calibration plays an important role in the improvement of positioning accuracy for parallel manipulators. Based on the specific geometric constraints of limbs, this paper presents a new kinematic parameter identification method for the widely studied 3-PRS parallel manipulator. In the proposed calibration method, the planes where the PRS limbs exactly located are identified firstly as the geometric characteristics of the studied parallel manipulator. Then, the limbs can be considered as planar PR mechanisms whose kinematic parameters can be determined conveniently according to the limb planes identified in the first step. The main merit of the proposed calibration method is that the system error model which relates the manipulator’s kinematic errors to the output ones is not required for kinematic parameter identification. Instead, only two simple geometric problems need to be established for identification, which can be solved readily using gradient-based searching algorithms. Hence, another advantage of the proposed method is that parameter identification of the manipulator’s limbs can be accomplished individually without interactive impact on each other. In order to validate the effectiveness and efficiency of the proposed method, calibration experiments are conducted on an apparatus of the studied 3-PRS parallel manipulator. The results show that using the proposed two-step calibration method, the kinematic parameters can be identified quickly by means of gradient searching algorithm (converge within five iterations for both steps). The positioning accuracy of the studied 3-PRS parallel manipulator has been significantly improved by compensation according to the identified parameters. The mean position and orientation errors at the validation configurations have been reduced to 1.56 × 10−4 m and 1.13 × 10−3 rad, respectively. Further, the proposed two-step kinematic calibration method can be extended to other limited-degree-of-freedom parallel manipulators, if proper geometric constraints can be characterized for their kinematic limbs.

CALIBRATION OF THE 3-PRS PARALLEL MANIPULATOR USING A MOTION CAPTURE SYSTEM

2005 ◽  
Vol 29 (4) ◽  
pp. 645-654
Author(s):  
C.G. van Driel ◽  
Juan A. Carretero
Keyword(s):  
Motion Capture ◽  
Parallel Manipulator ◽  
Kinematic Model ◽  
Calibration Method ◽  
Kinematic Calibration ◽  
Virtual Model ◽  
Motion Capture System ◽  
Parallel Mechanisms ◽  
Kinematic Parameters ◽  
Preliminary Testing

In this paper, a kinematic calibration method for the 3-PRS parallel manipulator using a motion capture system is presented. Although parallel mechanisms present numerous advantages over their serial counterparts, an accurate kinematic model must be developed to facilitate their operation. Kinematic calibration is used to accurately determine the kinematic parameters of the kinematic model to improve the overall accuracy of the mechanism. The kinematic calibration of the 3-PRS parallel manipulator will be examined by identification of the manipulator's kinematic parameters, an introduction to the motion capture system used, and the presentation of die calibration method itself. For preliminary testing purposes, a virtual model of the manipulator has been generated in CAD to validate the calibration method. The calibration method initially determines the joint locations and orientations, from which the remaining kinematic parameters can be resolved. Preliminary testing using the virtual model indicates the method is valid and can accurately determine the modelled parameters. Once the physical manipulator is operational, alterations the calibration method will be required to account for manufacturing and assembly tolerances/errors, joint offsets and noise during the static captures.

The Theory of Kinematic Parameter Identification for Industrial Robots

1988 ◽  
Vol 110 (1) ◽  
pp. 96-100 ◽  
Author(s):  
L. J. Everett ◽  
Tsing-Wong Hsu
Keyword(s):  
Parameter Identification ◽  
Recent Literature ◽  
Robot Manipulators ◽  
A Priori ◽  
Kinematic Parameter ◽  
Industrial Robots ◽  
Identification Algorithm ◽  
Kinematic Parameters ◽  
Independent Parameters ◽  
Kinematic Parameter Identification

This paper presents the concept of completeness for kinematic identification of robot manipulators. Completeness is defined as the ability to map joint positions into tool positions for all arbitrary manipulators. It is suggested that complete models must contain a certain number of independent parameters. Furthermore it is suggested (and shown by practical examples) that the required number of independent kinematic parameters is easy to determine a-priori. This enables one to check a model for completeness. Although the basic idea behind kinematic identification may have been considered well known, several identification algorithms in the recent literature are incomplete. Two examples are included in this paper. For this reason, this paper presents the topic and includes the conditions for a complete and viable identification algorithm.

scholarly journals Hybrid Optimal Kinematic Parameter Identification for an Industrial Robot Based on BPNN-PSO

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Guanbin Gao ◽  
Fei Liu ◽  
Hongjun San ◽  
Xing Wu ◽  
Wen Wang
Keyword(s):  
Parameter Identification ◽  
Bp Neural Network ◽  
Hybrid Algorithm ◽  
Industrial Robot ◽  
Pso Algorithm ◽  
Kinematic Parameter ◽  
Industrial Robots ◽  
Identification Algorithm ◽  
Kinematic Parameters ◽  
Kinematic Parameter Identification

A novel hybrid algorithm that employs BP neural network (BPNN) and particle swarm optimization (PSO) algorithm is proposed for the kinematic parameter identification of industrial robots with an enhanced convergence response. The error model of the industrial robot is established based on a modified Denavit-Hartenberg method and Jacobian matrix. Then, the kinematic parameter identification of the industrial robot is transformed to a nonlinear optimization in which the unknown kinematic parameters are taken as optimal variables. A hybrid algorithm based on a BPNN and the PSO is applied to search for the optimal variables which are used to compensate for the error of the kinematic parameters and improve the positioning accuracy of the industrial robot. Simulations and experiments based on a realistic industrial robot are all provided to validate the efficacy of the proposed hybrid identification algorithm. The results show that the proposed parameter-identification method based on the BPNN and PSO has fewer iterations and faster convergence speed than the standard PSO algorithm.

A New Measurement Device for Kinematic Calibration of Parallel Manipulators

2004 ◽  
Author(s):  
Abdul Rauf ◽  
Sung-Gaun Kim ◽  
Jeha Ryu
Keyword(s):  
Parallel Manipulators ◽  
Measurement Procedure ◽  
Initial Guess ◽  
Measurement Noise ◽  
Kinematic Calibration ◽  
Kinematic Parameters ◽  
End Effector ◽  
Experimental Procedure ◽  
New Device ◽  
Rotation Component

Kinematic calibration is a process that estimates the actual values of geometric parameters to minimize the error in absolute positioning. Measuring all the components of Cartesian posture assure identification of all parameters. However, measuring all components, particularly the orientation, can be difficult and expensive. On the other hand, with partial pose measurements, experimental procedure is simpler. However, all parameters may not be identifiable. This paper proposes a new device that can be used to identify all kinematic parameters with partial pose measurements. Study is performed for a 6 DOF (degree-of-freedom) fully parallel Hexa Slide manipulator. The device, however, is general and can be used for other parallel manipulators. The proposed device consists of a link with U joints on both sides and is equipped with a rotary sensor and a biaxial inclinometer. When attached between the base and the mobile platform, the device restricts the end-effector’s motion to 5 DOF and measures two position components and one rotation component of the end-effector. Numerical analyses of the identification Jacobian reveal that all parameters are identifiable. Computer simulations show that the identification is robust for the errors in the initial guess and the measurement noise. Intrinsic inaccuracies of the device can significantly deteriorate the calibration results. A measurement procedure is proposed and cost functions are discussed to prevent propagation of the inaccuracies to the calibration results.

Dynamic Calibration for Serial Robotic Manipulators Based on the Zero Position Analysis Method

1989 ◽  
Author(s):  
G. Z. Qian ◽  
K. Kazerounian
Keyword(s):  
Robotic Manipulators ◽  
Calibration Method ◽  
Dynamic Calibration ◽  
Calibration Model ◽  
Kinematic Calibration ◽  
Dynamic Parameters ◽  
Analysis Method ◽  
Kinematic Parameters ◽  
Position Analysis ◽  
Zero Position

Abstract In the continuation of a kinematic calibration method developed in a previous report, a new dynamic calibration model for serial robotic manipulators is presented in this paper. This model is based on the Zero Position Analysis Method. It entails the process of estimating the errors in the robot’s dynamic parameters by assuming that the kinematic parameters are free of errors. The convergence and effectiveness of the model are demonstrated through numerical simulations.

Geometric parameter identification of a dual-arm robot by using closed-chain constraint and optimization technique

2017 ◽  
Vol 232 (7) ◽  
pp. 1294-1302 ◽  
Author(s):  
Wu-Te Yang ◽  
Kuan-Lin Li ◽  
Kuei-Yuan Chan ◽  
Pei-Chun Lin
Keyword(s):  
Optimization Technique ◽  
Constraint Equation ◽  
Calibration Method ◽  
Kinematic Parameter ◽  
Motion Generation ◽  
Positioning Accuracy ◽  
Closed Chain ◽  
Controller Performance ◽  
Dual Arm Robot ◽  
Dual Arm

The positioning accuracy of the empirical robot manipulators is determined by various factors, such as kinematic accuracy, structure rigidity, and controller performance. Here, we report on the development of a new and straightforward technique to calibrate the kinematic parameters of a dual-arm robot under uncertainty. In comparison with other techniques, which generally rely on using other instruments to calibrate the manipulators, the proposed method utilizes the intrinsic characteristics of the dual-arm robot for calibration. In particular, when the two arms grasp each other, a formed closed chain can be operated as the constraint equation for the kinematic parameter optimization of the two arms. In the optimization process, the dual-arm robot has to pose in various configurations to yield better performance, and thus a motion generation strategy of the dual-arm robot is proposed, where one arm serves as the master to track the designated trajectory and the other arm serves as the slave to track the motion of the master arm by using a compliance control strategy. The proposed calibration method was experimentally validated, and the results confirm that the positioning accuracy of both arms can be improved.

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