Automated Guided Vehicle Control Research Articles

Modeling and Simulation Research of Heavy-duty AGV Tracking Control System Based on Magnetic Navigation

This paper studies tracking control problem which is applied on the 16-wheel heavy-duty AGV(Automated Guided Vehicle). Firstly, the trajectory detection scheme is designed based on magnetic navigation sensors. Secondly, the 16-wheel heavy-duty AGV control model is simplified as a two-wheel AGV model according to Ackermann steering principle, and fuzzy trajectory control regulation is established based on car driving experience. Finally, a trajectory control simulation system for circular/straight trajectories is built in MATLAB Simulink to verify the effectiveness on trajectory control.

Resource management in decentralized industrial Automated Guided Vehicle systems

This paper proposes an advanced decentralized method where an Automated Guided Vehicle (AGV) can optimally insert charging stations into an already assigned optimal tour of task locations. In today's industrial AGV systems, advanced algorithms and techniques are used to control the whole fleet of AGVs robustly and efficiently. While in academia, much research is conducted towards every aspect of AGV control. However, resource management or battery management is still one aspect which is usually omitted in research. In current industrial AGV systems, AGVs operate until their resource level drops below a certain threshold. Subsequently, they head to a charging station to charge fully. This programmed behaviour may have a negative impact on the manufacturing systems performance. AGVs lose time charging at inconvenient moments while this time loss could be avoided. Using the approach, an AGV can choose independently when it will visit a charging station and how long it will charge there. A general constrained optimization algorithm will be used to solve the problem and the current industrial resource management will be used as a benchmark. We use a simple extension of the Traveling Salesman Problem (TSP) representation to model our approach. The paper follows a decentral approach which is in the interest of the authors. The result of the proposal is a compact and practical method which can be used in today's operative central or decentral controlled AGV systems.

A Qualitative Analysis of a USB Camera for AGV Control.

The increasing use of Automated Guided Vehicles (AGV) in the industry points to a search for better techniques and technologies to adapt to market requirements. Proper position control and movement give an AGV greater movement accuracy and greater lateral oscillations stability and vibration. It leads to smaller corridors and leaner plants, to more relaxed shipment devices, and to greater safety in the transport of fragile loads, for instance. AGV control techniques are not new, but new sensors’ applications are possible, such as USB cameras. In this sense, it is necessary to ensure the sensor is adequate to control system requirements. This work addresses AGVs driven by passive floor demarcations. It presents a qualitative analysis of a USB camera as sensors for AGV control, not yet a common industrial application. We performed the experiments with a small AGV prototype on an eight-shaped lane, varying both camera parameters and AGV parameters, such as linear speed. The AGV uses a USB camera with different image processing settings—different morphological filters structuring elements shapes and sizes, and three different image resolutions—to analyze the factors that affect line detection and control processing. This paper’s main contribution is a qualitative and quantitative analysis for the different sensor configurations. In addition, it discusses the influence sources on camera image as a position sensor. Furthermore, the experiments confirm sensor pertinence for the proposed control system.

Multimodal speech and gesture control of AGVs, including EEG-based measurements of cognitive workload

Abstract Automated guided vehicles (AGVs) with autonomous behavior and decentralized human–machine interaction (HMI) are suitable for use in logistics. To facilitate natural interaction, HMI may involve both speech and gesture control. This paper presents a new cognitive approach based on electroencephalography (EEG) for multimodal HMI combining speech and gesture control for AGVs used in logistics. The results indicate that implicit EEG-based measures such as alertness and relaxation significantly affect speech control performance. Consequently, monitoring the user's cognitive workload during logistic operations may lead to a substantial improvement in work performance.

Design of the Automatic Guided Vehicle Control System Applied to Automotive Logistics

In order to improve the efficiency of auto parts distribution logistics, to lower the cost of auto production in transportation logistics, and to reduce accidents, in this paper it is designed that an automatic guided vehicle control system to replace the manned tractors in the distribution sites. The system is equipped with an infrared homing device that can ensure the automated guided vehicle (AGV) along a predetermined route automatic driving at a given distribution information, without the needs to manually guided. Test results show that the circuit performance of AGV control system is stable to ensure the accuracy of the tracking in the practical application, and the mean absolute error of the tracking is less than 0.04m.

Design of Double Lifting AGV Control System

In this paper, we designed a double lifting AGV (Automated Guided Vehicle) control system, and applied in automobile powertrain assembly line and axle assembly. Front and rear drive dynamics wear adopted in wheels drive mode, steering gears wear used in body rotating. Tapes were used in AGV navigation. Wi-fi was accessed to wireless for data transmission between AGVs and scheduling center. AGV and auto assembly line used PSD synchronous track detection device.

Autonomous Conveyance Control of AGV Based on Knowledge of Taxi Transportation Rules

Recently, demand has been increasing for various kinds and volumes of manufacturing systems. Also, the importance of the Automated Guided Vehicle (AGV) is increasing because it can flexibly correspond to the change of equipment in a factory. This paper describes an autonomous conveyance system for AGV based on a taxi transportation strategy. The system focuses on knowledge of a flexible taxi system in traffic engineering. A taxi is a transport unit in a traffic system with higher flexibility in traveling routes and arrival/departure points compared with railways and buses. In the present report, the waiting mode of a taxi is applied as an AGV rule and investigated to verify the effect of the proposed system. Moreover, the effect of multi-loaded AGV on system performance such as matching time and conveyance efficiency is investigated. A numerical experiment has been conducted to evaluate them. As a result, it was found that introduction of multi-loaded AGV is effective at reducing matching time without conveyance efficiency decrease.

New hybrid vision-based control approach for automated guided vehicles

Automated guided vehicles (AGVs) are a common choice made by many companies for material handling (MH) in manufacturing systems. AGV-based internal transport of raw materials, goods, and parts is becoming improved with advances in technology. Demands for fast, efficient, and reliable transport imply the usage of the flexible AGVs with onboard sensing and special kinds of algorithms needed for daily operations. So far, the majority of these transport solutions have not considered the modern techniques for visual servoing, monocular SLAM, and consequently, the usage of camera as onboard sensor for AGVs. In this research, a new hybrid control of AGV is proposed. The main control algorithm consists of two independent control loops: position-based control (PBC) for global navigation and image based visual seroving (IBVS) for fine motions needed for accurate steering towards loading/unloading point. By separating the initial transportation task into two parts (global navigation towards the goal pose near the loading/unloading point and fine motion from the goal pose to the loading/unloading point), the proposed hybrid control bypasses the need for artificial landmarks or accurate map of the environment. The state estimation of the robot pose is determined in terms of monocular SLAM, via extended Kalman filter coupled with feedforward neural network—the neural extended Kalman filter (NEKF). NEKF is used to model unknown disturbances and to improve the robot state transition model. The integration of the new hybrid control and NEKF has been tested in laboratory with the mobile robot and simple camera. Experimental results present the effectiveness of the proposed hybrid control approach.

Time Windows Based Dynamic Routing in Multi-AGV Systems

This paper presents a dynamic routing method for supervisory control of multiple automated guided vehicles (AGVs) that are traveling within a layout of a given warehouse. In dynamic routing a calculated path particularly depends on the number of currently active AGVs' missions and their priorities. In order to solve the shortest path problem dynamically, the proposed routing method uses time windows in a vector form. For each mission requested by the supervisor, predefined candidate paths are checked if they are feasible. The feasibility of a particular path is evaluated by insertion of appropriate time windows and by performing the windows overlapping tests. The use of time windows makes the algorithm apt for other scheduling and routing problems. Presented simulation results demonstrate efficiency of the proposed dynamic routing. The proposed method has been successfully implemented in the industrial environment in a form of a multiple AGV control system.

Dynamic analysis of AGV control under dead-reckoning algorithm

SUMMARYIn this paper, dead-reckoning localization errors for automated guided vehicles (AGVs) in indoors quasi-structured environments are studied. Based on error ellipse localization analysis, dead-reckoning errors arising from mismatched AGV wheels radius are investigated. The dynamic model for a differential-drive AGV type with mismatched wheels radius is also derived. The developed rationale shows that sensor fusion is a key feature for minimizing AGV localization errors. Two simulation scenarios and one experiment are presented to show system performance under AGV proportional-derivative (PD)-type control.

Development of an intelligent agent-based AGV controller for a flexible manufacturing system

Automated guided vehicles (AGVs) are the most flexible means to transport materials among workstations of a flexible manufacturing system. Complex issues associated with the design of AGV control of these systems are conflict-free shortest path, minimum time motion planning and deadlock avoidance. This research presents an intelligent agent-based framework to overcome the inefficacies associated with the aforementioned issues. Proposed approach describes the operational control of AGVs by integrating different activities such as path generation, journey time enumeration, collision and deadlock identification, waiting node location and its time estimation, and decision making on the selection of the conflict-free shortest feasible path. It represents efficient algorithms and rules associated with each agent for finding the conflict-free minimum time motion planning of AGVs, which are needed to navigate unidirectional and bidirectional flow path network. A collaborative architecture of AGV agent and its different modules are also presented. Three complex experimental scenarios are simulated to test the robustness of the proposed approach. It is shown that the proposed agent-based controller is capable of generating optimal, collision- and deadlock-free path with less computational efforts.

Deadlock handling for real-time control of AGVs at automated container terminals

In automated container terminals, situations occur where quay cranes, stacking cranes, and automated guided vehicles (AGVs), directly or indirectly request each other to start a specific process. Hence, all of the affected resources are blocked, possibly leading to the complete deadlock of individual cranes or AGVs. Particularly, AGVs are liable to deadlocks because they always need a secondary resource, either a quay crane or a stacking crane, to perform the pick-up and drop-off operations. Because usually no buffering of containers takes place at the interfaces between AGVs and cranes, the consequences of deadlocks are rather severe. Two different methods for the detection of deadlocks are presented. One is based on a matrix representation of the terminal system. The other directly traces the requests for the individual resources. To resolve deadlock situations arising in an automated container terminal, three different procedures are proposed. These procedures aim to modify the sequence of handling operations or to assign them to alternative resources so that conflicts between concurrent processes are resolved. The suitability of the concept is demonstrated in an extensive simulation study.

Efficient Simulator Based on Meta-Heuristic for FMS and AGV Systems Design and Control

Flexible Manufacturing Systems (FMS) based on Automated Guided Vehicles (AGV) have emerged as highly competitive manufacturing technologies of the last decade. However, their design and control are complex tasks since the decision problems related to the different system parameters such as sizing and scheduling are usually shown as NP-hard. Nowadays, computer simulation is one of the most commonly used methods for solving these problems. Now, we present a complete simulation tool which allows the design, analysis and control of FMS based on AGV. This tool is composed of three modules: (1) A simulation module which allows the estimation of the user introduced configuration. (2) An optimization module which is based on a meta-heuristic: the simulated annealing. This module is coupled with the simulation one in order to obtain an Executive Information System that is able to generate an optimal configuration. (3) A reactive control system which is based on the concept of real-time simulation and allows dynamic dispatching and routing of different systems inside the global FMS. The different developed modules have been validated by using a typical automated manufacturing system.

Intelligent agent framework to determine the optimal conflict-free path for an automated guided vehicles system

Agent technology has been considered as an important approach for developing intelligent manufacturing systems. It offers a new way of thinking about many of the classical problems in manufacturing engineering. The conflict resolution of automated guided vehicles (AGVs) in a flexible manufacturing systems (FMS) environment is one such problem that comes under this category. This paper describe a multi-agent approach to the operational control of AGVs by integration of path generation, enumerating time-windows, searching interruptions, adjusting waiting time and taking decisions on the selection of routes. It presents an efficient algorithm and rules for finding a conflict-free shortest-time path for AGVs, which is applicable to a bi- and unidirectional flow path network. The concept of loop formation in a flow path network is introduced to deal with the parking of idle vehicles, without obstructing the path of moveable AGVs. The concept of loop formation at nodes reduces the timing-taking task of finding the dynamic positioning of idle AGVs in the network.

A process modelling framework for AGV control

The control of handling equipment in a distribution centre is vital to overall control of the material handling process. A unified equipment and process modelling approach is adopted in this paper. The influence of automated guided vehicle (AGV) velocity and positioning control on the time needed to perform a material handling task, and the AGV service time are investigated. The salient features of this research are: modelling intelligent material handling in a distribution centre considering the effect of dynamic constraints on the velocity profiles of an automated handling equipment (a sideload forklift AGV); modelling and simulating controlled vision-based positioning of an AGV; and simulating the process model and drawing conclusions about the possible benefits of autonomous material handling.

Dynamic conflict-free routing of automated guided vehicles

This paper presents work performed to address design and operational control issues for an Automated Guided Vehicle (AGV) based material handling system. Various design issues connected with flow path design, such as traffic flow along the guide paths, location and representation of intersections, buffers, pickup and dropoff points, are outlined. A network representation of the AVG system (AGVS) is presented. Operational control factors, such as demand selection and assignment, route planning and traffic management, idle AGV positioning, and AGV characteristics, are addressed. In particular, the performance of six demand selection policies, four demand assignment policies, and two idle AGV positioning policies are outlined. A very effective route-generation technique that provides conflict-free routes for multiple AGVs with varying speeds is presented. A large-scale simulation of a dynamic batch type manufacturing system to test the feasibility of the proposed scheme for real time control of AGVs and to determine the effect of several factors on several performance measures is presented. Our findings indicate that performance is significantly affected by vehicle speed, number of vehicles, demand arrival interval, idle AGV positioning, and the demand selection and assignment policy in use.

Performance evaluation of tandem and conventional AGV systems using generalized stochastic Petri nets

Abstract This paper investigates the different policies and concepts followed in the traffic management of automated guided vehicle (AGV) systems, and develops the controls for automatically eliminating potential vehicle conflicts in an AGV system. The planning of the AGV system is performed in such a way that there are no conflicts or deadlocks for the vehicles using stochastic Petri nets (SPNs). The major effort is devoted to determining the benefits of the tandem AGV control in comparison with the conventional AGV control method. SPNs have been used to model the different designs of flexible manufacturing systems (FMSs) and with different policies for the movement of material, vehicle path control, inventory planning and tool control. The SPN model is solved and the performance of the system can be evaluated. In this study, the effort is directed to model an FMS with two different types of AGV traffic management methods, namely the conventional and tandem AGV control. A SPN program is used which takes ...

Steering Control of Automated Guided Vehicle by Neural Network.

Factory automation is advanced in industrial field, and then higher speed drive and performance are desired for an AGV (automated guided vehicle). A new steering control of AGV by fuzzy control has been proposed instead of the PI control. However, it is necessary much time to investigate the rules and to adjust the scaling factors for excellent performance in the fuzzy control. Thus, this is the matter to be solved.In this paper, a new steering control of AGV based on the neural network using the back propargation method is proposed. The good steering control results by the fuzzy control is adopted for the teaching signal of neural network. At the first step, the effect of the number of learning and the learning errors on the steering control results are discussed by the computer simulation using the AGV model. Further, the ability of generalization in the turning radius and the traveling speed is also investigated. It becomes clear that the AGV can travel along the traveling course provided that the neural network learns both of the right and left turning at the maximum traveling speed and the minimum turning radius. Then, it is proved by the experiment using the AGV built as a trial that the proposed steering control method is very available.

A Steering Control of Automated Guided Vehicle by Fuzzy Reasoning.

In recent year, fuzzy control has been applied to various industrial field and its availability has been reported. The purpose of application of fuzzy control is to realize the control performance using the experience of expert (control rules) with “If … Then …” rules. Now, easier operation and excellent performance of AGV (Automated Guided Vehicle) at high speed are required. The steering control of AGV with the conventional PI controller, however, becomes difficult to achieve the excellent performance. Therefore, the authors propose the steering control of AGV using fuzzy control, which can obtain stable steering control.In this paper, we discuss the optimal position of guide sensor and make an experiment in the straight traveling. We introduce many rules for fuzzy reasoning and discuss how to choose the rules for fuzzy reasoning and achieve the stable steering control. Then, the experiments of steering response for the step change of guide tape are carried out with the fuzzy control as well as the conventional PI control. The results of steering control using fuzzy control are better than that using PI control. It is confirmed that the proposed steering control is very available.