Forward Control Research Articles

Adaptive Path-Following Control for Autonomous Semi-Trailer Docking

Maneuvering a truck-trailer system while docking is extremely challenging. This article aims to alleviate this problem by presenting an enhanced path-following control framework for autonomous semi-trailer docking. In the proposed system, adaptive controllers that utilize gain scheduling are introduced for forward and reverse path-following tasks in docking maneuvers to increase the robustness and path-following performance. The system includes an improved pure pursuit controller with adaptive look-ahead distance for forward path following; a cascade controller of reverse pure pursuit and a gain-scheduled LQ control for reverse path-following. In the evaluation of the path-following performance of forward and reverse controllers, the closed-loop system of path-following controllers with the truck-trailer kinematic model is simulated in MATLAB/Simulink for various test cases, and the results are compared with those of other studies. Furthermore, different docking scenarios are generated via the cascade path planning algorithm for autonomous semitrailer docking. These are tested with a high degree semi-trailer model within the IPG TruckMaker simulation environment, and with a full truck-trailer vehicle in the test field. The results of both simulations and physical testing clearly demonstrate improvements in terms of the control problem formulation, i.e., the stabilized path-following is obtained with acceptable path-following errors.

Semi-Autonomous Forward and Backward Motion Control of Wheeled Mobile System Based on Dimensional Extension of Vector Field

Semi-Autonomous Forward and Backward Motion Control of Wheeled Mobile System Based on Dimensional Extension of Vector Field

Traditional practices: A window for water erosion management in the Argana basin (Western High Atlas Morocco)

Water and soil are two essential natural resources, which their preservation determines the local and national environmental sustainability. The pollution and erosion processes causing deterioration of these resources, which impacting negativaly the environment and economy development. This research aims to suggest the most straight forward and most appropriate control measures for the basins that are socially and economically acceptable for farmers. By consdering Argana basin as study area, the proposed approach consists, first, to analyze the soil loss map and, then, cconducted semi-structured interviews with local farmers at various locations across the basin. The results indicate that the areas of high and very high deterioration encompass 48 % of the basin’s surface. In addition, all of the farmers questioned used agroforestry on their managed sites. The study highlight the importtance of the traditional practices in fighting water erosion risk.

Improvement of the response of a vehicle body motion simulator using six-degree-of-freedom motion system

The vehicle dynamic performance of an automobile is greatly affected by the characteristics of a suspension system. In this study, a testing machine of a suspension with a 6-DOF motion system which reproduces the vehicle body movement is discussed. The dynamic characteristics of the motion system varies depending on the position and posture of the end effector and the applied force on it. The dynamic performance of the motion system was identified by the sweep excitation tests in this study, and the concept of the adaptive feed forward controller with considering the dynamic characteristics of the motion system was proposed.

Preparing to move: Setting initial conditions to simplify interactions with complex objects.

Humans dexterously interact with a variety of objects, including those with complex internal dynamics. Even in the simple action of carrying a cup of coffee, the hand not only applies a force to the cup, but also indirectly to the liquid, which elicits complex reaction forces back on the hand. Due to underactuation and nonlinearity, the object’s dynamic response to an action sensitively depends on its initial state and can display unpredictable, even chaotic behavior. With the overarching hypothesis that subjects strive for predictable object-hand interactions, this study examined how subjects explored and prepared the dynamics of an object for subsequent execution of the target task. We specifically hypothesized that subjects find initial conditions that shorten the transients prior to reaching a stable and predictable steady state. Reaching a predictable steady state is desirable as it may reduce the need for online error corrections and facilitate feed forward control. Alternative hypotheses were that subjects seek to reduce effort, increase smoothness, and reduce risk of failure. Motivated by the task of ‘carrying a cup of coffee’, a simplified cup-and-ball model was implemented in a virtual environment. Human subjects interacted with this virtual object via a robotic manipulandum that provided force feedback. Subjects were encouraged to first explore and prepare the cup-and-ball before initiating a rhythmic movement at a specified frequency between two targets without losing the ball. Consistent with the hypotheses, subjects increased the predictability of interaction forces between hand and object and converged to a set of initial conditions followed by significantly decreased transients. The three alternative hypotheses were not supported. Surprisingly, the subjects’ strategy was more effortful and less smooth, unlike the observed behavior in simple reaching movements. Inverse dynamics of the cup-and-ball system and forward simulations with an impedance controller successfully described subjects’ behavior. The initial conditions chosen by the subjects in the experiment matched those that produced the most predictable interactions in simulation. These results present first support for the hypothesis that humans prepare the object to minimize transients and increase stability and, overall, the predictability of hand-object interactions.

On the Parallel Kinematics of the FET Stretching Press in the Stretch Forming Operations in the Manufacture of Parts with Complex Spatial Geometry

The kinematics of a stretching press mechanism of a parallel structure are investigated. The kinematic dependences aimed at setting the spatial position of the working elements of a cross-stretching press of FET type, which allow positioning its jaws at any time during the technological operations, are obtained. The forward and inverse control kinematics problems of the jaw mechanism stretching press are solved

Forward and feedback control mechanisms of developmental tissue growth.

The size and proportions of animals are tightly controlled during development. How this is achieved remains poorly understood. The control of organ size entails coupling of cellular growth and cell division on one hand, and the measure of organ size on the other. In this review we focus on three layers of growth control consisting of genetic patterning, notably chemical gradients, mechanics and energetics which are complemented by a systemic control unit that modulates growth in response to the nutritional conditions and coordinates growth between different organs so as to maintain proportions. Growth factors, often present as concentration dependent chemical gradients, are positive inducers of cellular growth that may be considered as deterministic cues, hence acting as organ-intrinsic controllers of growth. However, the exponential growth dynamics in many developing tissues necessitate more stringent growth control in the form of negative feedbacks. Feedbacks endow biological systems with the capacity to quickly respond to perturbations and to correct the growth trajectory to avoid overgrowth. We propose to integrate chemical, mechanical and energetic control over cellular growth in a framework that emphasizes the self-organizing properties of organ-autonomous growth control in conjunction with systemic organ non-autonomous feedback on growth.

Modeling and Adaptive Control Law Design for a Bi-Tiltrotor Unmanned Aerial Vehicle

This paper presents modeling and control law design for a bi-tiltrotor unmanned aerial vehicle for autonomous payload delivery. An ultralight bi-tiltrotor aerial vehicle was developed for a payload delivery contest using only two motors attached to a carbon fiber tube with an additional cube basket to carry the payload. To achieve desirable three-dimensional (3D) trajectory tracking performance with unknown payload, an adaptive control system has been developed, which consists of two components: (1) a baseline control law, including a lateral speed controller, forward speed controller, yaw angle controller, and altitude controller; and (2) an adaptive augmentation to all these four channels to compensate for modeling uncertainties and disturbances caused by the payload, which has large influence on system dynamics due to the light weight of the vehicle. A mathematical model of the vehicle has been built using the Newton-Euler method and simplified based on reasonable assumptions to facilitate control design. The baseline control law employs conventional proportional-derivative control structure. Subsequently, L1 adaptive control theory is adopted in the adaptive augmentation design. Simulation examples verify the efficacy of the proposed adaptive control solution.

Application of Three-Dimensional Animation in Mechanical Control Mechanism

With the development of the times and the advancement of science and technology, the development of 3D animation has gradually been applied in various fields. In the field of mechanical control, three-dimensional animation has gradually become a very important application. In the actual application process, the use of three-dimensional animation effects cannot be applied in the field of mechanical control only by imagination. It must be applied in practice from the perspective of mechanical control. Analyze from its own stability and external factors to realize its application value. The purpose of this paper is to study the application of 3D animation in mechanical control mechanism. This article will take mechanical control as an entry point to discuss the application of three-dimensional animation in its mechanism. The research is carried out from two aspects. The first is the application of the robot arm. Based on the kinematic path planning of the shortest time priority strategy, the shorter the motion time of the robot arm, the faster the speed, and the vibration is more difficult to avoid. This is the vibration of the flexible arm. Improve its work efficiency, lay the foundation for more complex path planning problems; create conditions for lighter and faster robotic arm applications. The second is the application of the mechanical foot. The proposed ankle joint control strategy based on the lateral and forward cycle matching can be combined with the forward plane walking control strategy under the stable initial gait of the robot to realize the humanlike virtual prototype of the biped robot. Dynamic walking for analysis. Experimental investigations have shown that in the process of normal walking, there is a dynamic swing process and a static support process. The swing process refers to the lifting of the foot to move forward or backward, and the supporting process refers to the immobilization of one foot to the other. One fulcrum on each foot allows it to move forwards and backwards. Among them, the dynamic swing process accounts for 40% of the whole process, and the static support process accounts for 60%. In general, based on these data, the three-dimensional robotic arm and three-dimensional robotic foot can be better studied.

Самолёт-невидимка F-117А был сбит с помощью советских специалистов

The article discusses the history of the Stealth aircraft creation. The destruction of the F117A stealth aircraft in Yugoslavia, carried out with the participation of Soviet specialists and technologies, is described for the first time. The article analyzes the capabilities of VHF radar stations for the stealthy targets reconnaissance and for the improvement of the air defence forward edge information and control subsystem.

Performance enhancement of SRM using smart bacterial foraging optimization algorithm based speed and current PID controllers

In modern era, the switched reluctance motors (SRM) are gaining attraction due to its inherent features such as robustness, low cost, simple, rugged structure, excellent fault tolerance and temperature withstanding capability. With these specialized advantages, the accurate and efficient energy analysis is still a challenging one since they operated at variable reluctance and oscillating excitation characteristics resulting in nonlinear characteristics. This paper focused on the energy improvement and performance analysis inclusive of smooth control in speed and minimized torque ripples of SRM by introducing the novel Bio- inspired methodology named Bacterial Foraging Optimization Algorithm (BFOA) for the selection of optimal parameters of the PID speed and current controllers. By minimizing the torque ripples, it increases the average torque which in turn increases the energy conversion. The performance of the SRM is measured in terms of speed, current, power and efficiency and BFOA efficiency has been verified with genetic algorithm (GA) and conventional PID controller using Euler forward approximation method. This paper discusses the modeling, controlling strategy using BFOA, GA and Euler forward approximation method and a comprehensive analysis of energy using optimized selection of controlling parameters. The performance evaluation objectives in this work, is to minimize Integral Square Error of both current and speed controller and also the reduction of torque ripples. The results obtained in this method are also compared with the Genetic Algorithm and Euler forward approximation-based controllers. The proposed algorithm employs individual and social intelligences, which in turn search the responses between the local optima along with global optimums of the problem adaptively. The outmost dynamic response increased average torque and minimized current ripple can be obtained when the parameters of PID controllers are optimized using BFOA.

First-row transition metal compounds for aqueous metal ion batteries

In recent years, a series of aqueous metal ion batteries (AMIBs) has been developed to improve the safety and cost-efficiency of portable electronics and electric vehicles. However, the significant gaps in energy density, power density, and cycle stability of AMIBs directly hinder them from replacing the currently widely used non-aqueous metal ion batteries, which stems from the lack of reasonable configuration and performance optimization of electrode materials. First-row transition metal compounds (FRTMCs), with the advantages of optional voltage ranges (from low to high), adjustable crystal structures (layered and tunnel types with large spacing), and designable morphology (multi-dimensional nanostructures), are widely used to construct high-performance AMIBs. However, no comprehensive review papers were generated to highlight their specific and significant roles in AMIBs. In this review, we first summarize the superiority and characteristics of FRTMCs in AMIBs. Then, we put forward control strategies of FRTMCs from subsurface engineering to inner construction to promote capacitance control and diffusion control energy storage. After that, the electrochemical performance of the FRTMCs regulation strategies in AMIBs is reviewed. Finally, we present potential directions and challenges for further enhancements of FRTMCs in AMIBs. The review aims to provide an in-depth understanding of regulation strategies for enhancing energy storage to build high-performance AMIBs that meet practical applications.

Patching Based Extra Short Packet Forward Error Control Coding for Ultra-Reliable Low Latency Communications (URLLC) in 5G

Patching Based Extra Short Packet Forward Error Control Coding for Ultra-Reliable Low Latency Communications (URLLC) in 5G

Progress in prevention and control of viral hepatitis since the establishing of the People's Republic of China

China has the highest disease burden of viral hepatitis. After understanding the epidemic characteristics of viral hepatitis in China and putting forward scientific prevention and control strategies, the Chinese government has been effectively practicing the policy of "prevention first with combination of prevention and control". Over the past 40 years, China has taken effective measures to promote vaccination, strengthen blood screening, standardize diagnosis and treatment services and strengthen supervision, and achieved remarkable success. The incidence of hepatitis A decreased from 52.6 per 100,000 in 1990 to 1.38 per 100,000 in 2019, the HBsAg prevalence among children under 5 years of age decreased from 9.67% in 1992 to 0.32% in 2014, and the cure rate of chronic hepatitis C patients has reached more than 95%. The incidence of hepatitis E is also on the decline. However, in 2019, the estimated diagnosis rate for hepatitis B patients is 25% and treatment rate is 17%; hepatitis C diagnosed rate is 30% and only 9% of the diagnosed were treated. This still falls far from the target of 90% diagnosis rate and 80% treatment rate by 2030. Relevant policies should be implemented as soon as possible, health promotion should be carried out, and screening and diagnosis and treatment services should be strengthened to promote timely treatment for more chronically infected people.

The Performance and Future of QUIC Protocol in the Modern Internet

Quick UDP Internet Connections (QUIC) protocol is a potential replacement for the TCP protocol to transport HTTP encrypted traffic. It is based on UDP and offers flexibility, speed, and low latency. The performance of QUIC is related to the everyday web browsing experience. QUIC is famous for its Forward Error Correction (Luyi, Jinyi, & Xiaohua, 2012) and congestion control (Hari, Hariharan, & Srinivasan, 1999) algorithm that improves user browsing delay by reducing the time spent on loss recovery (Jörg, Ernst, & Don, 1998). This paper will compare QUIC with other protocols such as HTTP/2 over TCP, WebSocket, and TCP fast open in terms of latency reduction and loss recovery to determine the role of each protocol in the modern internet. Furthermore, this paper will propose potential further improvements to the QUIC protocol by studying other protocols.

Capacity Optimality of AMP in Coded Systems

This paper studies a large random matrix system (LRMS) model involving an arbitrary signal distribution and forward error control (FEC) coding. We establish an area property based on the approximate message passing (AMP) algorithm. Under the assumption that the state evolution for AMP is correct for the coded system, the achievable rate of AMP is analyzed. We prove that AMP achieves the constrained capacity of the LRMS with an arbitrary signal distribution provided that a matching condition is satisfied. As a byproduct, we provide an alternative derivation for the constraint capacity of an LRMS using a proved property of AMP. We discuss realization techniques for the matching principle of binary signaling using irregular low-density parity-check (LDPC) codes and provide related numerical results. We show that the optimized codes demonstrate significantly better performance over un-matched ones under AMP. For quadrature phase shift keying (QPSK) modulation, bit error rate (BER) performance within 1 dB from the constrained capacity limit is observed.

Theoretical and experimental investigation on an integral time-delay feedback control combined with a closed-loop control for an infinitely variable transmission system

A nonlinear closed-loop speed ratio control combined with an integral time-delay feedback control is developed to adjust the speed ratio of an infinitely variable transmission (IVT) for a desired output speed with any variable input speed. The speed ratio control of the IVT system is developed based on its nonlinear dynamic model, which involves a forward speed controller and a crank length controller for varying operating conditions. The closed-loop forward speed controller can operate with efficient driving performance based on an optimal operation line of a prime mover. System identification is carried out to achieve high control performance of the IVT system. Comprehensive results of experimental investigation are presented to validate the proposed control strategy for the IVT system. An instrumented rotation speed measurement system is designed so that quantities necessary for the time-delay control variable can be measured. Experimental results show that the speed ratio of the IVT with the proposed control strategy can achieve an excellent tracking response for the desired constant output speed. This study reveals that fluctuations of the output speed of the IVT system can be reduced by time-delay feedback control.

PI+Feed Forward Controller Tuning Based on Genetic Algorithm for Liquid Level Control of Coupled-Tank System

One of the main problems in the control of the coupled tank liquid level systems, which are used frequently in water treatment systems and petrochemical industry today, is to determine the water flow rate between the two tanks. In this paper, proportional-integral +feed forward control method (PI+FF), whose parameters are determined using genetic algorithm (GA), one of the heuristic optimization methods, is used to solve this problem. In addition, in order to show the performance of the GA-based controller, the PI+FF controller that PI parameters obtained using the Ziegler-Nichols (Z-N) method are applied to the same system and the real-time application results of both controllers are compared. The experimental results showed that the controller, which parameters are determined by GA, reached the desired reference value with less settling time and less overshooting when it compared to the Z-N method based controller, and also it has given faster response to sudden changes in the system.

Predictive analysis of the number of human brucellosis cases in Xinjiang, China

Brucellosis is one of the major public health problems in China, and human brucellosis represents a serious public health concern in Xinjiang and requires a prediction analysis to help making early planning and putting forward science preventive and control countermeasures. According to the characteristics of the time series of monthly reported cases of human brucellosis in Xinjiang from January 2008 to June 2020, we used seasonal autoregressive integrated moving average (SARIMA) method and nonlinear autoregressive regression neural network (NARNN) method, which are widely prevalent and have high prediction accuracy, to construct prediction models and make prediction analysis. Finally, we established the SARIMA((1,4,5,7),0,0)(0,1,2)12 model and the NARNN model with a time lag of 5 and a hidden layer neuron of 10. Both models have high fitting performance. After comparing the accuracies of two established models, we found that the SARIMA((1,4,5,7),0,0)(0,1,2)12 model was better than the NARNN model. We used the SARIMA((1,4,5,7),0,0)(0,1,2)12 model to predict the number of monthly reported cases of human brucellosis in Xinjiang from July 2020 to December 2021, and the results showed that the fluctuation of the time series from July 2020 to December 2021 was similar to that of the last year and a half while maintaining the current prevention and control ability. The methodology applied here and its prediction values of this study could be useful to give a scientific reference for prevention and control human brucellosis.

Eco-Friendly Speed Control Algorithm Development for Autonomous Vessel Route Planning

The upcoming autonomous vessel voyage is promising future in the maritime sector. However, so far, the contemporary route decision making technologies rely on human intervention. Therefore, this manuscript proposes the two newly developed speed algorithms: the modified fixed speed control and the wave feed forward speed control in the route decision making procedure for the autonomous vessels. These two algorithms can control the vessel’s speed without human intervention in eco-friendly and economic manner. The first algorithm is the wave feed forward speed control that can predict the speed change according to wave loads and compensate it to reduce the fluctuation of speed, power, and fuel consumption. To develop this algorithm, the real time modeling of the wave added resistance and the wave real time effect on propulsion are analyzed. The efficacy of the developed wave feed forward scheme is validated using the in-house route optimization simulation program through comparisons with the results of conventional speed governor control case. The developed schemes are applied to a 173 K LNG (Liquefied Natural Gas) carrier with twin propulsion. The other proposed speed control algorithm is the modified fixed control algorithm. This algorithm improves the conventional fixed power control algorithm by adding a time marching module to satisfy the required time arrival of the voyage. The two proposed methods are analyzed in the various simulations—ideal environmental conditions and real voyage environments: The Pacific and the Atlantic cases. Based on the results, the suggested methods can reduce fuel oil consumption, gas emission, and wear and tear problem of the propulsion devise of ship. In the study, it is clearly demonstrated that the developed wave feed forward speed control and modified fixed power scheme perform much better than the conventional speed governor control case.