Automation

12 pages, 858 KiB

Open AccessArticle

Finite-Time Trajectory Tracking of Second-Order Systems Using Acceleration Feedback Only

by Romain Delpoux, Thierry Floquet and Hebertt Sira-Ramírez

Automation 2021, 2(4), 266-277; https://doi.org/10.3390/automation2040017 - 16 Dec 2021

Cited by 3 | Viewed by 3023

In this paper, an algebraic approach for the finite-time feedback control problem is provided for second-order systems where only the second-order derivative of the controlled variable is measured. In practice, it means that the acceleration is the only variable that can be used for feedback purposes. This problem appears in many mechanical systems such as positioning systems and force-position controllers in robotic systems and aerospace applications. Based on an algebraic approach, an on-line algebraic estimator is developed in order to estimate in finite time the unmeasured position and velocity variables. The obtained expressions depend solely on iterated integrals of the measured acceleration output and of the control input. The approach is shown to be robust to noisy measurements and it has the advantage to provide on-line finite-time (or non-asymptotic) state estimations. Based on these estimations, a quasi-homogeneous second-order sliding mode tracking control law including estimated position error integrals is designed illustrating the possibilities of finite-time acceleration feedback via algebraic state estimation. Full article

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14 pages, 3299 KiB

Open AccessArticle

Colored 3D Path Extraction Based on Depth-RGB Sensor for Welding Robot Trajectory Generation

by Alfonso Gómez-Espinosa, Jesús B. Rodríguez-Suárez, Enrique Cuan-Urquizo, Jesús Arturo Escobedo Cabello and Rick L. Swenson

Automation 2021, 2(4), 252-265; https://doi.org/10.3390/automation2040016 - 5 Nov 2021

Cited by 10 | Viewed by 4562

Abstract

The necessity for intelligent welding robots that meet the demand in real industrial production, according to the objectives of Industry 4.0, has been supported owing to the rapid development of computer vision and the use of new technologies. To improve the efficiency in weld location for industrial robots, this work focuses on trajectory extraction based on color features identification on three-dimensional surfaces acquired with a depth-RGB sensor. The system is planned to be used with a low-cost Intel RealSense D435 sensor for the reconstruction of 3D models based on stereo vision and the built-in color sensor to quickly identify the objective trajectory, since the parts to be welded are previously marked with different colors, indicating the locations of the welding trajectories to be followed. This work focuses on 3D color segmentation with which the points of the target trajectory are segmented by color thresholds in HSV color space and a spline cubic interpolation algorithm is implemented to obtain a smooth trajectory. Experimental results have shown that the RMSE error for V-type butt joint path extraction was under 1.1 mm and below 0.6 mm for a straight butt joint; in addition, the system seems to be suitable for welding beads of various shapes. Full article

(This article belongs to the Special Issue Networked Predictive Control for Complex Systems)

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14 pages, 18303 KiB

Open AccessCommunication

Design and Implementation of a Robotic Arm Assistant with Voice Interaction Using Machine Vision

by George Nantzios, Nikolaos Baras and Minas Dasygenis

Automation 2021, 2(4), 238-251; https://doi.org/10.3390/automation2040015 - 31 Oct 2021

Cited by 4 | Viewed by 8827

Abstract

It is evident that the technological growth of the last few decades has signaled the development of several application domains. One application domain that has expanded massively in recent years is robotics. The usage and spread of robotic systems in commercial and non-commercial environments resulted in increased productivity, efficiency, and higher quality of life. Many researchers have developed systems that improve many aspects of people’s lives, based on robotics. Most of the engineers use high-cost robotic arms, which are usually out of the reach of typical consumers. We fill this gap by presenting a low-cost and high-accuracy project to be used as a robotic assistant for every consumer. Our project aims to further improve people’s quality of life, and more specifically people with physical and mobility impairments. The robotic system is based on the Niryo-One robotic arm, equipped with a USB (Universal Serial Bus) HD (High Definition) camera on the end-effector. To achieve high accuracy, we modified the YOLO algorithm by adding novel features and additional computations to be used in the kinematic model. We evaluated the proposed system by conducting experiments using PhD students of our laboratory and demonstrated its effectiveness. The experimental results indicate that the robotic arm can detect and deliver the requested object in a timely manner with a 96.66% accuracy. Full article

(This article belongs to the Collection Smart Robotics for Automation)

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18 pages, 3771 KiB

Open AccessArticle

A New Transformer-Less Structure for a Boost DC-DC Converter with Suitable Voltage Stress

by Farzad Mohammadzadeh Shahir, Meysam Gheisarnejad and Mohammad-Hassan Khooban

Automation 2021, 2(4), 220-237; https://doi.org/10.3390/automation2040014 - 11 Oct 2021

Cited by 6 | Viewed by 3150

Abstract

In this paper, a new structure is proposed for a boost dc–dc converter based on the voltage-lift (VL) technique. The main advantages of the proposed converter are its lack of transformer, simple structure, free and low input current ripple, high voltage gain capability by using an input source, suitable voltage stress on semiconductors and lower output capacitance. Herein, the analysis of the proposed converter operating and its elements voltage and current relations in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are presented, and the voltage gain of each operating mode is individually calculated. Additionally, the critical inductance, current stress of switches, calculation of passive components’ values and efficiency are analyzed. In addition, the proposed converter is compared with other studied boost converters in terms of ideal voltage gain in the CCM and the number of active and passive components, maximum voltage stress on semiconductors, and situation of input current ripples. The correctness of the theoretical concepts is examined from the experimental results using the laboratory prototype. Full article

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Automation, Volume 2, Issue 4 (December 2021) – 4 articles

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