Dynamic Identification of Industrial Robots from Low-Sampled Data

2013 ◽  
Vol 328 ◽  
pp. 644-650 ◽  
Author(s):  
E. Oliva ◽  
G. Berselli ◽  
F. Pini
Keyword(s):  
Previous Literature ◽  
Industrial Robots ◽  
Sampled Data ◽  
Dynamic Identification ◽  
Inertial Parameters ◽  
Novel Method ◽  
Friction Models

This paper proposes a fast and on-site method for the dynamic identification of industrial robots from low-sampled position and torque data. Owing to the basic architecture of the employed controller, only trapezoidal-velocity trajectories can be enforced for identification purposes. Differently from previous literature, where this kind of trajectories were performed with limited joint velocities and range of motions, the procedure proposed hereafter is characterized by fast movements performed on wide angular ranges. Furthermore, in order to identify the influence of friction without deriving complex friction models, a novel method is outlined that decouples frictional torques from gravitational, centrifugal and inertial ones. Finally, although multiple experiments of different kinds have been performed, inertial parameters are determined in one singular step, thus avoiding possible error increase due to sequential identification algorithms.

scholarly journals A Novel Method for the Micro-Clearance Measurement of a Precision Spherical Joint Based on a Spherical Differential Capacitive Sensor

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3366 ◽  
Author(s):  
Wen Wang ◽  
He Yang ◽  
Min Zhang ◽  
Zhanfeng Chen ◽  
Guang Shi ◽  
...  
Keyword(s):  
Capacitive Sensor ◽  
Differential Capacitance ◽  
Industrial Robots ◽  
Parallel Mechanisms ◽  
Spherical Joint ◽  
Compact Structure ◽  
Spacing Variation ◽  
Novel Method ◽  
The Mathematical Model ◽  
Fringe Effect

A spherical joint is a commonly used mechanical hinge with the advantages of compact structure and good flexibility, and it becomes a key component in many types of equipment, such as parallel mechanisms, industrial robots, and automobiles. Real-time detection of a precision spherical joint clearance is of great significance in analyzing the motion errors of mechanical systems and improving the transmission accuracy. This paper presents a novel method for the micro-clearance measurement with a spherical differential capacitive sensor (SDCS). First, the structure and layout of the spherical capacitive plates were designed according to the measuring principle of capacitive sensors with spacing variation. Then, the mathematical model for the spatial eccentric displacements of the ball and the differential capacitance was established. In addition, equipotential guard rings were used to attenuate the fringe effect on the measurement accuracy. Finally, a simulation with Ansoft Maxwell software was carried out to calculate the capacitance values of the spherical capacitors at different eccentric displacements. Simulation results indicated that the proposed method based on SDCS was feasible and effective for the micro-clearance measurement of the precision spherical joints with small eccentricity.

Real-time velocity scaling and obstacle avoidance for industrial robots using fuzzy dynamic movement primitives and virtual impedances

2018 ◽  
Vol 45 (1) ◽  
pp. 110-126 ◽  
Author(s):  
Iman Kardan ◽  
Alireza Akbarzadeh ◽  
Ali Mousavi Mohammadi
Keyword(s):  
Real Time ◽  
Obstacle Avoidance ◽  
Time Constant ◽  
Fuzzy System ◽  
Industrial Robots ◽  
Simple Method ◽  
Content Type ◽  
Dynamic Movement ◽  
Steering Mechanism ◽  
Novel Method

Purpose This paper aims to increase the safety of the robots’ operation by developing a novel method for real-time implementation of velocity scaling and obstacle avoidance as the two widely accepted safety increasing concepts. Design/methodology/approach A fuzzy version of dynamic movement primitive (DMP) framework is proposed as a real-time trajectory generator with imbedded velocity scaling capability. Time constant of the DMP system is determined by a fuzzy system which makes decisions based on the distance from obstacle to the robot’s workspace and its velocity projection toward the workspace. Moreover, a combination of the DMP framework with a human-like steering mechanism and a novel configuration of virtual impedances is proposed for real-time obstacle avoidance. Findings The results confirm the effectiveness of the proposed method in real-time implementation of the velocity scaling and obstacle avoidance concepts in different cases of single and multiple stationary obstacles as well as moving obstacles. Practical implications As the provided experiments indicate, the proposed method can effectively increase the real-time safety of the robots’ operations. This is achieved by developing a simple method with low computational loads. Originality/value This paper proposes a novel method for real-time implementation of velocity scaling and obstacle avoidance concepts. This method eliminates the need for modification of original DMP formulation. The velocity scaling concept is implemented by using a fuzzy system to adjust the DMP’s time constant. Furthermore, the novel impedance configuration makes it possible to obtain a non-oscillatory convergence to the desired path, in all degrees of freedom.

scholarly journals Reconstructing Compressor Non-Uniform Circumferential Flow Field From Spatially Undersampled Data: Part 2 — Practical Application for Experiments

2020 ◽  
Author(s):  
Fangyuan Lou ◽  
Douglas R. Matthews ◽  
Nicholas J. Kormanik ◽  
Nicole L. Key
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
High Speed ◽  
Static Pressure ◽  
Pressure Field ◽  
Leading Edge ◽  
Pressure Profile ◽  
Sampled Data ◽  
Mean Values ◽  
Novel Method

Abstract In the previous part of the paper, a novel method to reconstruct the compressor non-uniform circumferential flow field using spatially under-sampled data points is developed. In this part of the paper, the method is applied to two compressor research articles to further demonstrate the potential of the novel method in resolving the important flow features associated with these circumferential non-uniformities. In the first experiment, the static pressure field at the leading edge of a vaned diffuser in a high-speed centrifugal compressor is reconstructed using pressure readings from nine static pressure taps placed on the hub of the diffuser. The magnitude and phase information for the first three dominant wavelets are characterized. Additionally, the method shows significant advantages over the traditional averaging methods for calculating repeatable mean values of the static pressure. While using the multi-wavelet approximation method, the errors in the mean static pressure with one dropout measurement are 70% less than the pitchwise-averaging method. In the second experiment, the full-annulus total pressure field downstream of Stator 2 in a three-stage axial compressor is reconstructed from a small segment of data representing 20% coverage of the annulus. Results show very good agreement between the reconstructed total pressure profile and the experiment at a variety of spanwise locations from near hub to near shroud. The features associated with blade-row interactions accounting for passage-to-passage variations are resolved in the reconstructed total pressure profile.

scholarly journals Detecting and quantifying changing selection intensities from time-sampled polymorphism data

2015 ◽  
Author(s):  
Hyunjin Shim ◽  
Stefan Laurent ◽  
Matthieu Foll ◽  
Jeffrey Jensen
Keyword(s):  
Sampled Data ◽  
Design Strategies ◽  
Fluctuating Selection ◽  
Serial Data ◽  
Novel Method ◽  
Polymorphism Data ◽  
Selection Intensities ◽  
Approximate Bayesian ◽  
Parameter Ranges ◽  
Shed Light

During his well-known debate with Fisher regarding the phenotypic dataset ofPanaxia dominula, Wright (1948) suggested fluctuating selection as a potential explanation for the observed change in frequency. This model has since been invoked in a number of analyses, with the focus of discussion centering mainly on random or oscillatory fluctuations of selection intensities. Here, we present a novel method to consider non-random changes in selection intensities using Wright-Fisher approximate Bayesian (ABC)-based approaches, in order to detect and evaluate a change in selection strength from time-sampled data. This novel method jointly estimates the position of a change point as well as the strength of both corresponding selection coefficients (and dominance for diploid cases) from the allele trajectory. The simulation studies of CP-WFABC reveal the combinations of parameter ranges and input values that optimize performance, thus indicating optimal experimental design strategies. We apply this approach to both the historical dataset ofPanaxia dominulain order to shed light on this historical debate, as well as to whole-genome time-serial data from influenza virus in order to identify sites with changing selection intensities in response to drug treatment.

Detection of Motion Error Under Synchronous Two-Axis Control of a Dual Arm Robot Based on Monitoring of Ball Rolling Motion on a Plate

2015 ◽  
Vol 9 (1) ◽  
pp. 33-42
Author(s):  
Wei Wu ◽  
◽  
Shun Kinoshita ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama
Keyword(s):  
Cooperative Control ◽  
Rolling Friction ◽  
Industrial Robots ◽  
Circular Path ◽  
Motion Error ◽  
Rotary Axes ◽  
Ball Rolling ◽  
Novel Method ◽  
Dual Arm Robot ◽  
Dual Arm

Dual-arm industrial robots have been gaining attention as novel tools in the field of new automation. We therefore focus on them to flexibly control both the linear motion and the rotational motion of a working plate. However, the difficulty of measuring the synchronous accuracy of two rotary axes without a highaccuracy gyro sensor has been a problem. We therefore propose a novel method of using a ball to measure the synchronous accuracy of two rotary axes of a working plate. The plate uses dual-arm cooperative control to keep the ball rolling in a circular path on it. In this report, we investigate the effects of the rolling friction coefficient of the ball on its sensitivity and resolution to estimate the synchronous accuracy of two rotary axes.

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