Automated Guided Vehicle (AGV), abbreviated as AGV, refers to a transport vehicle equipped with electromagnetic or optical automatic guidance devices, capable of driving along designated guidance paths, with safety protection and various load transfer functions. In industrial applications, AGV does not require a driver and uses rechargeable batteries as its power source. It is generally possible to control its travel route and behavior through a computer, or use electromagnetic tracks to set up its travel route. The electromagnetic tracks are glued to the floor, and unmanned transport vehicles follow the information brought by the electromagnetic tracks to move and move.
The unmanned handling vehicle system is a complex control system, and with the addition of systems with different requirements, it increases the complexity of the system. Therefore, the software configuration design of the system supports the entire process of path planning, process design, and system simulation project for AGV project implementation plan. The upper level system provides a flexible tool for defining AGV system processes, which can plan or modify paths or system processes according to the actual needs of users. Lower level systems also provide a programming language that can define different AGV functions for users.
AGV is characterized by wheeled mobility and has advantages over walking, crawling, or other non wheeled mobile robots, such as fast movement, high work efficiency, simple structure, strong controllability, and good safety. Compared with other commonly used equipment in material transportation, the activity area of AGV does not require fixed devices such as tracks and support frames, and is not limited by the site, roads, and space. Therefore, in automated logistics systems, their automation and flexibility can be fully reflected, achieving efficient, economical, and flexible unmanned production.
Below is an introduction to the composition of the unmanned transport vehicle system:
1、 Ground control system
The AGV Ground Control System, also known as the AGV Upper Control System, is the core of the AGV system. Its main function is to allocate tasks, manage vehicles, traffic, and communication among multiple AGVs in the AGV system (AGVS).
Task management: Task management is similar to process management in computer operating systems, providing an interpretation and execution environment for AGV ground control programs; Provide scheduling based on task priority and start time; Provide various operations for tasks such as starting, stopping, and canceling.
Vehicle management: Vehicle management is the core module of AGV management. It allocates and schedules AGV execution tasks based on the request of material handling tasks, calculates the shortest walking path of AGV based on the principle of shortest walking time, controls and commands the walking process of AGV, and timely issues loading and unloading and charging commands.
Traffic management: Based on the physical size, operational status, and path conditions of AGVs, provide measures for AGVs to automatically avoid each other, while avoiding deadlock methods for vehicles waiting for each other and methods for releasing deadlocks; The traffic management of AGV mainly includes walking segment allocation and deadlock reporting functions.
Communication management: Communication management provides communication functions between AGV ground control system and AGV single machine, ground monitoring system, ground IO equipment, vehicle simulation system, and upper computer. The communication between AGVs requires wireless communication and the establishment of a wireless network. AGVs only communicate in both directions with ground systems, without any communication between AGVs. The ground control system adopts a polling method and communicates with multiple AGVs; TCP/IP communication is used for communication with ground monitoring system, vehicle simulation system, and upper computer.
Vehicle drive: The small car drive is responsible for collecting the AGV status and issuing permission requests to the traffic management for the walking section, while also issuing the confirmation section to the AGV.
2、 Vehicle control system
The AGV Onboard System, also known as the AGV single machine control system, is responsible for the navigation, guidance, path selection, vehicle driving, loading and unloading operations of the AGV single machine after receiving instructions from the upper system.
Navigation: An AGV uses its own navigation devices to measure and calculate its position and heading in global coordinates.
Guidance: The AGV single machine calculates the speed and steering angle values for the next cycle based on its current position, heading, and pre-set theoretical trajectory, that is, the command value for AGV movement.
Path selection (Searching): Based on the instructions of the upper system, the AGV single machine selects the path to be run in advance through calculation, and reports the results to the upper control system. Whether it can run or not is uniformly allocated by the upper system according to the location of other AGVs. The path of AGV single machine walking is designed based on actual working conditions, and it consists of several segments. Each segment indicates the starting and ending points of the segment, as well as information such as the AGV's driving speed and steering direction during that segment.
Vehicle Driving: AGV single machine controls vehicle operation through servo devices based on guidance calculation results and path selection information.
The Guidance Principle of AGV
The guidance method of AGV is a constantly evolving technology. At present, most of them use optical and computer-guided technology. The next step will be self guidance, which is also the most advanced guidance method for AGVs. There are two steering methods for AGVs, one is to use differential steering control, which is currently used by military tanks. It increases the speed of one wheel compared to the other, resulting in a turning effect; The two sensors in front of the vehicle are equipped to detect turn signals, and the amplitude detectors on the vehicle determine the turning amplitude based on the signal size on both sides. Another steering method is the steering wheel steering method, which usually only has one front wheel and follows the path of the laid guide bar. When a phase difference is detected, the vehicle generates a steering action to compensate for this difference. This type of vehicle is commonly used in assembly line trucks, tractor trucks, single load trucks, shelf trucks, as well as forklifts and light load trucks. The differential steering device can only be used on assembly line vehicles, single load vehicles, forklifts, and light load vehicles, unlike tractors and manually operated vehicles such as rack trucks.
Advantages of AGV
(1) High degree of automation;
Controlled by computers, electrical control equipment, laser reflectors, etc.
When auxiliary materials are needed in a certain section of the workshop, the staff inputs relevant information to the computer terminal, which then sends the information to the central control room. Professional technicians issue instructions to the computer, and with the cooperation of the electrical control equipment, this instruction is finally received and executed by the AGV - sending the auxiliary materials to the corresponding location.
(2) Charging automation;
When the AGV car is about to run out of battery, it will send a request command to the system, requesting charging (usually technicians set a value in advance), and automatically "queue up" at the charging location when the system allows it.
In addition, the battery life of AGV cars is very long (more than 10 years), and they can work for about 4 hours every 15 minutes of charging.
(3) Aesthetics enhance the viewing experience, thereby enhancing the image of the enterprise.
(4) Convenient, reducing footprint; The AGV cars in the production workshop can shuttle back and forth between different workshops.
It is expected that in the coming years, AGV cars will appear in workshops in various industries. As automated unmanned handling equipment, AGV cars can reduce manual labor intensity and improve work efficiency. At the same time, it can skillfully and quickly complete some "impossible tasks". For example, the assembly workshops of large equipment such as automobiles, aerospace, and chemical industries introduce AGV cars to achieve point-to-point automatic access and handling operations, achieving precision, flexibility, informatization, shortening logistics time, reducing product losses, and reducing construction investment costs. The application scope of AGV is constantly expanding, and how to develop AGV system technology that can meet various user needs (function, price, quality) is a practical problem that we must face in the future.
