Vragen

Welcome to the Frequently Asked Questions section. The FAQ are categorized in different categories:

Current Chapters

1. Company Related FAQ
2. General AGV-System Related FAQ
3. Technical AGV-System Related FAQ

1. Company Related FAQ

Where does the name FROG come from?

FROG is an acronym for Free Ranging On Grid. Free ranging refers to the fact that the vehicles are not restricted to a fixed route, but can transverse spaces by means of any route desired. 'On Grid' refers to the internationally patented means of calibration by means of a systematic pattern of reference point embedded in the ground. However, Frog also offers calibration by means of laser or dGPS.

When was Frog AGV Systems established?

Frog AGV Systems was established in 1984. At first, the company specialized in industrial automation consultancy. In this capacity, Frog was asked to a solution for automated transportation in an outdoor environment. As the technologies of that time proved unable to perform the task, the FROG-concept was developed. Nowadays, the development and marketing of soft- and hardware for Automated Guided Vehicle Systems (and the application in several markets) is the core competency of the company.

What is the core competency of Frog AGV Systems?

The core competency is the development of the FROG-technology and all related AGV software and AGV hardware. Frog AGV Systems has several business units, which actively approach the focus market.

In which markets is Frog AGV Systems active?

Frog AGV Systems main activities are in the industrial AGV market. Please refer to our Industries menu. The company provides customers a global support through its offices in the Netherlands, Germany and the USA and worldwide network of partners and licensees.

Is Frog AGV Systems part of a larger, international organisation?

Frog AGV Systems is a fully independent, Dutch company, which is privately funded.


2. General AGV-system Related FAQ

What does an AGV system consist of?

An AGV system typically consists of vehicles and the supervisory control system. The supervisory control system is responsible for fleet management, traffic control and job generation and assignment. An exception to this set-up is an AGV-system with just a single AGV. In this case the supervisory control system may not be required.

What are the advantages of an AGV system?

The advantages of an AGV system are numerous ranging from a reduction of the operational costs to a safer working environment with no damage to goods and stationary infrastructure. Through all these benefits the payback time of an AGV system is between 1 and 5 years.
Compared to other material handling systems, AGVs provide superior flexibility and only use minimal space. System (lay-out) changes can easily be accommodated and fluctuations or (rapid) growth is facilitated as well.

What is the average payback time for an AGV-system?

Generally an AGV-system will have a payback of less than 3 years. This, however, always depends on the scope and complexity of the application. Frog AGV Systems has realized system with payback times of shorter than 1,5 years.

Can AGVs operate in the same environment as employees?

Every AGV is equipped with a range of safety sensors and can be integrated into any environment safely. Besides safety sensors such as the non-contact obstacle detection sensor (laser of infrared) and the contact sensitive bumper, the AGVs are equipped with audio and visual warning signals. Also emergency-buttons are present on the AGV.

What is the maintenance requirement of an AGV-system?

The maintenance requirement for each AGV system is different and depends on the customer as well. Frog AGV Systems provides customized maintenance contracts, taking into account the application as well the capabilities of the maintenance personnel al ready employed by the customer. Extensive classroom and hands on training can be provided to familiarize personnel with the maintenance of the system. However, a full service contract, including hot line support 24hrs. per day is also possible.

What type of AGV (technology) is most suited for me?

One-size-fits-all does not apply for AGV-systems. Depending on the characteristics of the application and the requirements set by customers, an AGV-system is designed. The AGV itself can be a standard vehicle, or can be custom designed. Specific parameters such as the type of calibration (grid or laser) can also be adjusted to meet the demands of the application. The supervisory control system SuperFROG will be tailored to the application as well.


3. Technical AGV-System Related FAQ

How does a FROG automated vehicle navigate?

The Frog AGV navigates by means of odometry, supported by regular re-calibration with external reference point. Driving and steering encoders on the drive wheels, which provide information on traveled distance and orientation change, support position calculation. For further orientation accuracy a gyro unit can be installed. Odometry is in principal sufficient for accurate navigation. In practice, small inaccuracies occur, resulting mainly from wheel spin and changes in wheel diameter (e.g. due to load variations). These inaccuracies accumulate over the distance traveled, thus creating the need for calibration to correct possible inaccuracies.

What guidance-technologies are there for Automated Guided Vehicles?

Please refer to the section 'vehicle navigation' of the education centre for a complete description of the different existing technologies.

Why should I consider calibration by means of a grid and not with laser?

Calibration by means of grid and laser provide the same free ranging capabilities and accuracy. In terms of reliability and costs the grid compares favourably to laser. Generally the most suited type of calibration will be determined based on the characteristics of the application and the requirements of the customer.

What is the maximum speed of an AGV?

The maximum speed depends on the application and applicable regulations. In an indoor environment approximately 1m/s is a common speed, while a maximum of 4m/s can also be achieved. In outdoor applications speeds are usually higher an can go up to 70 k/ph (45 m/ph) for the Phileas bus.

What type of controller is on-board the AGV?

An on-board navigation controller consisting of a dedicated I/O board with a PC104 CPU board controls the Frog AGV. This on-board controller, the FrogBox, takes care of vehicle tasks like navigation, communication and safety functions.

What would happen if magnets are not read/missed?

It can happen that a magnet is not read or a magnet could be missed. Based on the accuracy of the odometry, a missed magnet will not hinder safe operations. If several magnets in line are not read or missed, the error margin will accumulate. For this reason usually a maximum distance or allowed amount of magnets to be missed is defined, which can differ based on the characteristics of the application and the requirements of the customer.

What if an extra magnet is purposely dropped on the floor?

The calibration is done based on reference points (magnets). All magnets will be detected, but only the readings of magnets detected in the same area as they were expected to be encountered by the vehicle, will be processed and used for calibration. The confirmation of the additional magnet is logged in the on-board computer.

What type of communication is used?

Vehicles (FROG) communicate with SuperFROG using WLAN 802.11b radio frequency.

How does it communicate?

The Frog control software on-board of the vehicles communicates with the supervisory control system SuperFROG by means of an on-board spread-spectrum Wireless LAN radio. The vehicles do not communicate directly with each other; the communication is always between FROG and SuperFROG.

What communication protocol is used?

The communication protocol is based on the contention model: a party (FROG or SuperFROG) that wants to send first checks if the communication channel is free. If this is the case it starts sending, otherwise it will wait until the channel is free again. Collisions can occur if two parties decide at the same time that the channel is free and start to send.
Received packets are checked for integrity: the actual checksum, packet length, and sequence number have to correspond with the information sent with the package.
If a packet is received without error, the receiving party will acknowledge this to the sender. If the sender receives no acknowledgement in time, it will resend the packet (up to a certain number of retries). Reliable two-way communication is thus achieved.

What is the functionality of the supervisory control system?

The supervisory control system, SuperFROG is responsible for fleet and traffic management. The system is required for running a multiple number of vehicles, active infrastructure supports (like automatic door systems) and/or co-ordination with other installations. The supervisory control system can synchronize the wayside themeing based on the knowledge of the time synchronized actual position of the vehicles within the ride.

On what type of platform is the supervisory control system based?

SuperFROG operates on a Linux-platform on a regular office-PC. All systems and communications are performed real-time, except for the display of the actual position of the vehicles in the layout on screen. It is possible to display the user-interface on a PC operating on a windows-platform.

Can the supervisory control system also operate under Windows NT?

SuperFROG can run on two different platforms: on an HP workstation under HP-UX or on a PC under Linux. The user interface of the control system can be displayed in a Windows enviroment.

What does SuperFROG consist of?

SuperFROG consists of two software programs: a user interface and an internal program.
The internal program is responsible for communication with external systems, vehicle management and control of infrastructure equipment and possibly wayside. The internal program communicates with other systems by means of the spread spectrum wireless LAN.
The graphical user interface handles all user interactions with the control system. SuperFROG can support multiple user interface modules at different locations in the layout at the expense of additional computer hardware. The user interface contains different overviews of the system: layout definition, dispatch monitoring, vehicle monitoring, graphical layout monitoring (visual display) and statistics monitoring.

How can I get my layout into the supervisory control system?

The routes cannot be imported into the supervisory control system, but it is possible to import the layout of the plant as an aid to marking out the routes (in .dxf format). The supervisory control system includes a layout editor. The routes can easily be modified in this editor.

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