scholarly journals Geometric analysis of measurement errors in a surface metrology class with closed-loop probes

Measurement ◽  
2021 ◽  
pp. 109869
Author(s):  
Yao-yuan Hu ◽  
Ran Zhao ◽  
Bing-feng Ju
Keyword(s):  
Measurement Errors ◽  
Closed Loop ◽  
Geometric Analysis ◽  
Surface Metrology

An Autonomous Docking Mechanism for Vertical Lift Unmanned Aircraft

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
John Papayanopoulos ◽  
Kevin Webb ◽  
Jonathan Rogers
Keyword(s):  
Measurement Errors ◽  
Closed Loop ◽  
Mechanical Design ◽  
Tracking System ◽  
Unmanned Aircraft ◽  
Wide Range ◽  
Air Vehicle ◽  
Docking Mechanism ◽  
Infrared Tracking ◽  
Autonomous Docking

Abstract Unmanned aerial vehicles are increasingly being tasked to connect to payload objects or docking stations for the purposes of package transport or recharging. However, autonomous docking creates challenges in that the air vehicle must precisely position itself with respect to the dock, oftentimes in the presence of uncertain winds and measurement errors. This paper describes an autonomous docking mechanism comprising a static ring and actuated legs, coupled with an infrared tracking device for closed-loop docking maneuvers. The dock’s unique mechanical design enables precise passive positioning such that the air vehicle slides into a precise location and orientation in the dock from a wide range of entry conditions. This leads to successful docking in the presence of winds and sensor measurement errors. A closed-loop infrared tracking system is also described in which the vehicle tracks an infrared beacon located on the dock during the descent to landing. A detailed analysis is presented describing the interaction dynamics between the aircraft and the dock, and system parameters are optimized through the use of trade studies and Monte Carlo analysis with a three degree-of-freedom simulation model. Experimental results are presented demonstrating successful docking maneuvers of an autonomous air vehicle in both indoor and outdoor environments. These repeatable docking experiments verify the robustness and practical utility of the dock design for a variety of emerging applications.

scholarly journals Stability analysis of closed loop TRMS with observer based reliable H infinity controller using Kharitonov’s stability theorem

2018 ◽  
Vol 7 (2.21) ◽  
pp. 106
Author(s):  
Vidya S. Rao ◽  
V I. George ◽  
Surekha Kamath ◽  
C Shreesha
Keyword(s):  
Stability Analysis ◽  
Measurement Errors ◽  
Closed Loop ◽  
Multiple Input Multiple Output ◽  
Stability Theorem ◽  
H Infinity ◽  
Actuator Failures ◽  
Stability Bound ◽  
Input Multiple Output ◽  
Equipment Wear

The laboratory Twin Rotor Multiple Input Multiple Output System (TRMS) serving as a model of a helicopter has un modeled errors in its model, due to linearization, measurement errors, equipment wear, sensors or/and actuator failures. This mismatch is termed as uncertainties in the model. Due to sensor and actuator failure there would exist a large range of uncertainties. In this paper, the range of robust stability bound for closed loop TRMS along with observer based reliable H infinity controller using Kharitonov’s stability theorem is found. The variation in parameters of TRMS from its nominal values are shown. The Kharitonov’s stability analysis on TRMS proves that within the mentioned uncertainty limit the TRMS along with observer based reliable H infinity controller gives the closed loop stable response. 

scholarly journals Event-Triggered Adaptive Backstepping Control for Strict-Feedback Nonlinear Systems with Zero Dynamics

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Bo Xu ◽  
Xiaoping Liu ◽  
Huanqing Wang ◽  
Yucheng Zhou
Keyword(s):  
Measurement Errors ◽  
Closed Loop ◽  
Control Strategies ◽  
Design Procedure ◽  
Adaptive Controller ◽  
Zero Dynamics ◽  
Feedback Systems ◽  
Adaptive Backstepping ◽  
Event Triggered ◽  
Strict Feedback

This paper focuses on the problem of event-triggered control for a class of uncertain nonlinear strict-feedback systems with zero dynamics via backstepping technique. In the design procedure, the adaptive controller and the triggering event are designed at the same time to remove the assumption of the input-to-state stability with respect to the measurement errors. Besides, we propose an assumption to deal with the problem of zero dynamics. Three different event-triggered control strategies are designed, which guarantees that all the closed-loop signals are globally bounded. The effectiveness of the proposed methods is illustrated and compared using simulation examples.

Gain bounds in the minimal controller synthesis algorithm

1998 ◽  
Vol 212 (5) ◽  
pp. 345-360 ◽  
Author(s):  
D P Stoten ◽  
S E M Sebusang
Keyword(s):  
Measurement Errors ◽  
Closed Loop ◽  
Term Effect ◽  
Controller Synthesis ◽  
Synthesis Algorithm ◽  
Long Term Effect ◽  
High Responsiveness ◽  
Noise Disturbances ◽  
Modified Algorithm

Owing to its high responsiveness to noise disturbances, the minimal controller synthesis (MCS) algorithm can occasionally suffer from the long-term effect of measurement errors, resulting in gain wind-up, closed-loop signal aliasing and hence instability. To counteract this effect, an algorithm is proposed that extends MCS in such a way as to confine the adaptive gain evolutions by using automatically adjusting bounding ‘corridors’. The proof of stability is based upon the original version for MCS, and an implementation study supports the theoretical assertions that the modified algorithm prevents gain wind-up without significantly compromising adaptive effort.

Image-Processing Techniques Applied to the Study of the Musculoskeletal System and Its Interactions with Biomaterials

MRS Bulletin ◽  
2000 ◽  
Vol 25 (1) ◽  
pp. 38-42
Author(s):  
A. Merolli ◽  
P. Tranquilli Leali
Keyword(s):  
Image Processing ◽  
Signal To Noise Ratio ◽  
Geometric Analysis ◽  
Computer Applications ◽  
Source Image ◽  
Computer Assisted ◽  
Surface Metrology ◽  
Computerized Image Processing ◽  
Long Time ◽  
Histological Images

Over the past decade, orthopedic surgery and related research have made increasing use of the opportunities offered by computers. Many clinical and research procedures rely on medical images (e.g., x-ray films and histology) and their numerical evaluation (e.g., geometric analysis and surface metrology). This has led to the development of computer applications in orthopedics, with computer graphics playing a fundamental role. The image-processing field has also been studied in greater depth, with a view toward enhancing systems automation.Image processing relies on capturing measurable variations in some image parameters (e.g., light intensity, color, and signal-to-noise ratio). The extracted numerical values then can be used to modify the source image. From this definition, image processing can be considered a measurement technique, and in this light it has been introduced into histomorpho-metrical practice.Image processing speeds up routine analysis procedures by evaluating, in a less tedious and quicker way, a greater number of images, parameters, or both. Semiautomated computerized image-processing systems have been in use for a long time, based on computer-assisted analysis of objects whose contours were tracked manually by a digitizing cursor. Histological images were, generally, projected from the microscope over a digitizing tablet, with the operator visually recognizing the structure of interest and picking up its contours. The critical advance brought to histomorphometry by semiautomated techniques has been the practical measurement of surface-related parameters.

scholarly journals A Path Tracking Strategy for Car Like Robots with Sensor Unpredictability and Measurement Errors

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3077 ◽  
Author(s):  
Madan Mohan Rayguru ◽  
Mohan Rajesh Elara ◽  
Balakrishnan Ramalingam ◽  
M. A. Viraj J. Muthugala ◽  
S. M. Bhagya P. Samarakoon
Keyword(s):  
Motion Control ◽  
Measurement Errors ◽  
Feedback Linearization ◽  
Closed Loop ◽  
Sliding Mode ◽  
Observer Design ◽  
Sliding Mode Controller ◽  
Control Input ◽  
Robust Observer ◽  
Uncertain Dynamics

This work is inspired by motion control of cleaning robots, operating in certain endogenous environments, and performing various tasks like door cleaning, wall sanitizing, etc. The base platform’s motion for these robots is generally similar to the motion of four-wheel cars. Most of the cleaning and maintenance tasks require detection, path planning, and control. The motion controller’s job is to ensure the robot follows the desired path or a set of points, pre-decided by the path planner. This control loop generally requires some feedback from the on-board sensors, and odometry modules, to compute the necessary velocity inputs for the wheels. As the sensors and odometry modules are prone to environmental noise, dead-reckoning errors, and calibration errors, the control input may not provide satisfactory performance in a closed-loop. This paper develops a robust-observer based sliding mode controller to fulfill the motion control task in the presence of incomplete state measurements and sensor inaccuracies. A robust intrinsic observer design is proposed to estimate the input matrix, which is used for dynamic feedback linearization. The resulting uncertain dynamics are then stabilized through a sliding mode controller. The proposed robust-observer based sliding mode technique assures asymptotic trajectory tracking in the presence of measurement uncertainties. Lyapunov based stability analysis is used to guarantee the convergence of the closed-loop system, and the proposed strategy is successfully validated through numerical simulations.

Measurement Errors in Closed-Loop Frequency Response Estimates

1980 ◽  
Vol 102 (1) ◽  
pp. 13-20
Author(s):  
P. W. Davall ◽  
P. N. Nikiforuk
Keyword(s):  
Frequency Response ◽  
Measurement Errors ◽  
Closed Loop ◽  
Power Spectra ◽  
Open Loop ◽  
Feedback Signal ◽  
Single Input Single Output ◽  
Closed Loop Systems ◽  
Single Output ◽  
Single Input

The sampling distributions associated with frequency response estimates of single input, single output closed-loop systems are derived for the case where both the output and feedback signal measurements are subject to added noise. This work is an extension of that done by Goodman [1-3] and Akaike [4, 5] on open-loop systems. Conditions for response estimate bias are investigated and approximate distributions for the power spectra estimates of the added noise terms are derived.

scholarly journals Machine integrated telecentric surface metrology in laser structuring systems

ACTA IMEKO ◽  
2014 ◽  
Vol 2 (2) ◽  
pp. 73 ◽  
Author(s):  
Robert Schmitt ◽  
Tilo Pfeifer ◽  
Guilherme Mallmann
Keyword(s):  
Closed Loop ◽  
Optical Measurement ◽  
Surface Structures ◽  
Innovative Technology ◽  
Surface Metrology ◽  
Closed Loop Control ◽  
Loop Control ◽  
Structured Surfaces ◽  
Laser Structuring ◽  
Micro Structures

The laser structuring is an innovative technology used in a broad spectrum of industrial branches. There is, however, a market trend to smaller and more accurate micro structures, which demands a higher level of precision and efficiency in this process. In this terms, an inline inspection is necessary, in order to improve the process through a closed-loop control and early defect detection. Within this paper an optical measurement system for inline inspection of micro and macro surface structures is described. Measurements on standards and laser structured surfaces are presented, which underline the potential of this technique for inline surface inspection of laser structured surfaces.

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