Automated Guided Vehicles - The Right Material Handling Solution ...

Automated guided vehicles travel along a pre-determined route or path. This path can be physical (e.g. marked on the floor with magnetic tape or tags) or virtual (programmed through the AGV's navigation software).

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An AGV’s position and its movement are calculated and controlled using a combination of software (such as ANT lab) and sensors (such as LiDAR-based laser scanners). Together these technologies are what guides an AGV. They help the vehicle understand: where it is currently, where it needs to go (and what to do when it gets there), and how to get there.

Advanced AGVs can work alone or as part of a larger connected fleet. AGV fleet management software (such as ANT server) is used to schedule tasks, distribute these between vehicles, and control traffic.

How are AGVs powered?

Although early generation AGVs often used diesel power, these days automated vehicles are almost always battery powered. Many use automatic charging stations, meaning they do not need to be plugged in manually.

What is the speed of a typical AGV?

An AGV’s speed is a fine balance between achieving optimal efficiency (maximizing the number of missions per shift) and making sure the vehicle is safe (ensuring optimum stopping distances). Most AGVs on the market today reach speeds of up to 1.5 m/s (3.3 mph). Vehicles that are driven by ANT navigation can drive up to 3.5 m/s (7.8 mph). With some vehicles and applications even faster speeds are possible, but safety must always remain the priority.

What types of AGV steering are available?

There are many different types of AGV steering. The most common are shown below.

Types of AGV navigation technology

Automated guided vehicles typically move around by following pre-defined paths or routes. Different AGV navigation methods accomplish this in different ways, but generally speaking two main methods exist:

1. Following virtual or digital paths that exist only in the vehicle’s software
2. Following physical lines (line following) or tags on the ground

Physical path following

Automated vehicles that follow physical lines of some sort have been in use for several decades.

With line following types of AGV navigation, vehicles are literally guided through the facility by a physical line, such as:

• Magnetic tape
• Inductive wire (installed in or under the floor)
• Painted lines
• Tags (spaced intermittently in a line)

In the case of a tape-following AGV for instance, this features a downward-facing sensor that ‘looks’ at a line on the floor. It then measures the left and right error, and corrects the vehicle’s trajectory as needed. Tag following works in a similar way.

Virtual path following

Automated vehicles that follow virtual paths are newer. There are several types of virtual path following technology, the key difference between them being how they calculate the position of the vehicle (localization).

These technologies include:

• Laser triangulation (also called laser guidance)
• Vision guidance (also called optical navigation)
• Natural navigation (also called free navigation or SLAM navigation)

Laser triangulation uses references in the form of permanently-installed reflective targets to triangulate the position of the vehicle. It does this by firing beams around the space from a laser scanner installed on the vehicle. As its name implies, at least three targets must be recognized at any one time.

Vision guidance uses cameras to recognize features in the environment. These features are then compared to a 3D map in order for the vehicle to calculate its position and navigate effectively.

Natural navigation uses data from a vehicle’s laser scanners (often the AGV’s safety scanners) to calculate the vehicle’s position. It does this by comparing or ‘matching’ the laser scanner data to either: the cells of a grid-based 2D reference map of the environment (scan matching), or permanent map references like walls (natural feature navigation).

1. How is the vehicle installed?

You may have explored a vehicle’s functionality, but have you considered how it is installed? Will it take a matter of hours, just a few days, or weeks of integration with third-party personnel on-site disrupting your normal operations?

The main factor determining commissioning times is the type of navigation technology used to run the vehicle. AGVs based on natural navigation, such as ANT navigation, are typically quick to install since they do not require permanent changes to a site’s infrastructure.

Read -> AGV integration explained

2. How easy is it to modify routes?

Businesses change and sites evolve. At some point you are likely to want to change the routes that your AGVs travel. Will this be as simple as reprogramming digital (virtual) paths, or will updates require more substantial and time-consuming physical changes? Make sure your AGV investment is not going to create a large new expense every time your needs change.

3. How easily can you scale up your AGV fleet?

You may not require multiple automated vehicles today, but if your AGV installation is a success then you might in future. Adding a new vehicle to your operation should not mean a whole new installation project, so look closely at what fleet management options are offered with the AGV you are considering. Make sure you understand how easy it is, and how long it takes, to add new vehicles to your project.

Also, will a supplier’s fleet management software tie you to one type or brand of vehicle? Or can it accommodate other brands of AGV (as ANT navigation can), so that you are not locked into one vehicle vendor and have the widest possible choice of vehicles?

4. What kind of maintenance plan is offered?

Automated guided vehicles are only useful when they are doing what they are programmed to do, so be sure you plan how to keep them working.

Ensure you have access to an AGV maintenance plan that suits your business’ needs and budget. You should typically budget around 10% of an AGV’s sticker price for maintenance per year.

5. How proven is the system in real-world applications?

You need to understand the risks associated with your choice. So, be sure to understand whether you are an AGV startup’s first customer, or whether the company has thousands of vehicles installed and proven in global applications. Ideally, try to speak to several other users of your preferred AGV system before you sign that purchase order.

The Importance of AGV Safety in Industrial Environments

With the increasing adoption of AGVs in the industrial sector worldwide, ensuring their safe operation is paramount. These autonomous vehicles often share spaces with human workers, making safety a critical factor in maintaining a productive and accident-free workplace. AGV manufacturers must stay vigilant in designing and upgrading vehicles to meet the latest safety standards in a competitive market.

Regulatory Compliance and Safety Standards

European Directives, particularly the Low Voltage Directive (LVD) and Machinery Directive (MD), enforce compliance with normalized safety standards. LVD focuses on electrical safety, while MD encompasses broader safety requirements, including essential safety features and risk reduction strategies. Compliance with these standards not only ensures legal adherence but also enhances reliability, market access, and overall trust in the safety of AGVs.

Applicable standards

The most applicable normalized standards under them would be:

1. ISO -4:: This is the key standard for AGV safety in Europe, covering driverless industrial trucks and their systems.
2. EN  is a European standard that provides supplementary safety requirements for industrial trucks, including AGVs. This standard is designed to work in conjunction with other standards, such as EN ISO , to ensure comprehensive safety coverage for industrial trucks in various operating conditions.
3. EN series is a European standard suite specifically focused on the electrical and electronic safety requirements for industrial trucks, including those used in AGV systems.
4. EN ISO : This standard pertains to the safety-related parts of control systems, defining performance levels (PL) from PL a to PL e required for different safety components.
5. EN -1: is a European standard that addresses the safety of machinery concerning the electrical equipment of machines. This standard is essential for ensuring that machinery operates safely within industrial environments, including AGV.
6. ISO : is a widely adopted international standard for functional safety of electrical/electronic/programmable electronic systems (E/E/PE systems) in safety-related applications. The standard provides a framework for ensuring the safety of these systems by defining a Safety Integrity Level (SIL) classification system.
7. EN : This standard outline general principles for risk assessment and risk reduction.

Safety Integrity Level (SIL) and Performance Level (PL) in Functional Safety

The Safety Integrity Level (SIL) and Performance Level (PL) are two related but distinct concepts in the context of functional safety, as defined in the international standards ISO -1 and IEC . SIL is a measure of the probability of a safety function failing to perform its intended safety function, while PL is a measure of the performance of a safety function in terms of its ability to detect and respond to faults. In other words, SIL is concerned with the reliability of the safety function, while PL is concerned with the effectiveness of the safety function in preventing or mitigating the effects of a fault. These two concepts are crucial in ensuring the safety of complex systems, such as industrial automation, transportation, and healthcare, where the failure of a safety function can have severe consequences.

PLr and PL (From ISO -1:)

 a  ≥10-5 and <10-4
(0.001% to 0.01%)  b  ≥3 × 10-6 and <10-5
(0.% to 0.001%)  c  ≥10-6 and <3 × 10-6
(0.% to 0.%)  d  ≥10-7 and <10-6
(0.% to 0.%)  e  ≥10-8 and <10-7
(0.% to 0.)

SIL Levels According to IEC / IEC

SI

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Safety Integrity Level

PFDavg

Average probability of 

failure on demand per year

RRF

Risc Reduction Factor

PFDavg

Average probability of failure

on Demand per hour

 SIL 4 ≥10-5  and <10-4 to   ≥10-9  and <10-8   SIL 3  ≥10-4  and <10-3 to    ≥10-8  and <10-7    SIL 2 ≥10-3  and <10-2    to 100  ≥10-7  and <10-6    SIL 1 ≥10-2  and <10-1   100 to 10  ≥10-6  and <10-5  

Safety System Development Process

Developing a safety system involves several critical steps, ensuring the system meets safety goals, complies with industry standards, and enhances market competitiveness:

1. Hazard Analysis, Risk Assessment, and Standards Identification:
   Analyze the hazards associated with the application(s) and assess the risks to determine the required level of safety (safety goals). During this step, identify the specific industry standards and regulations that the safety solution must comply with.
2. Market Investigation of Compliant Solutions:
   Research and evaluate the available safety solutions that align with both the safety goals and the identified standards. Ensure that the potential solutions are capable of meeting the required compliance criteria.
3. Pre-evaluation of Safety and Standards Compliance:
   Assess the safety level of the proposed solution(s) and ensure they meet the necessary safety standards before proceeding with implementation. This step involves verifying that the solutions not only address safety requirements but also adhere to the applicable standards.
4. Implementation and Assembly:
   Assemble and implement the selected safety solution(s), following the guidelines and requirements outlined by the relevant standards. Ensure that all components are installed and configured correctly to meet both safety and compliance objectives.
5. Validation of Implementation and Compliance:
   Conduct a thorough validation of the implemented safety solution(s) to confirm that they meet the defined safety goals and comply with the identified standards. This may involve testing, inspections, and other verification activities.
6. Reporting and Certification Process:
   Document the entire process, including the hazard analysis, risk assessment, solution implementation, and validation outcomes. Prepare and submit the necessary reports for certification to demonstrate that the safety solution complies with all relevant standards and regulations.

Roboteq Safety Solutions

Roboteq stands out as a leading provider of drive solutions, offering critical safety products for AGVs. Our Safe Torque Off (STO) implementation, certified under IEC EN -5-2, achieves SIL 3 Cat 3 PL e across multiple products, including the latest RoboG4® series. We also offer the Safety Brake Switch (SBS), delivering two safety function:

• Dynamic Braking (Safety-rated three-phase short)
• Motor Brake Control (MBC)

Both enhancing AGV safety by ensuring rapid and reliable vehicle halting, compliant with ISO Cat 3 PL d.

Incorporating these advanced safety solutions ensures that your AGVs not only meet regulatory requirements but also operate with the highest safety standards, safeguarding both workers and the industrial environment.

General Safety Requirements

While Roboteq provides critical safety solutions for AGVs, there are additional safety measures that manufacturers and integrators need to consider to build a compliant and robust safety-rated system. These requirements go beyond our scope but are essential for ensuring the overall safety and reliability of AGVs in industrial environments. Here are some general safety requirements that every AGV manufacturer should take into account:

1. Overall Control System: This includes a safety PLC to manage and coordinate all safety functions.
2. Sensor Technology: Safety sensors are used for obstacle detection and monitoring safety loops to ensure the vehicle operates within safe parameters.

3. Physical Safeguards: Mechanical designs provide physical barriers and protective measures to prevent accidents.

4. Environmental and Operational Safety: This considers the surrounding environment and operational conditions to ensure the system adapts and remains safe, regardless of external factors.

5. Power Supply and Cable Management: Proper handling of power supply and cable management is crucial for maintaining system integrity and preventing issues such as electrical interference (EMI), which can compromise the safety system's reliability.

6. Additional Components: Depending on the specific application, other safety components may be required to meet the necessary safety standards and ensure comprehensive protection.These are tasks that need to be performed by the AGV manufacturer/integrator and Roboteq can not assist with these.

IFA SISTEMA

For engineers looking to implement and assess safety within their AGV systems, the IFA SISTEMA tool is an invaluable resource. Developed by the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA), SISTEMA is designed to evaluate the safety integrity of individual safety functions as well as the overall safety of the system.

To facilitate the evaluation process, Roboteq has developed a comprehensive SISTEMA library. This library includes Roboteq products equipped with safety-certified functions, allowing users to efficiently assess and ensure that their systems meet the highest safety standards. By using Roboteq’s advanced solutions in conjunction with the SISTEMA tool, manufacturers can streamline the process of achieving compliance with safety regulations and standards.

Download the SISTEMA Tool Engineers can download the SISTEMA tool from the following link:

IFA SISTEMA Download

Roboteq SISTEMA example

By importing our library to SISTEMA and setting up a simple Project with a simple safety function, we can evaluate a combination of FBLGT STO function coupled with the SBS (Safety Brake Switch) and we can identify the safety level of a system that is comprised of these two elements.

To create a new project, we need to just press new. Then name the project as desired. Then add a Safety Function and name it as desired.

To import the Roboteq library first download it from Roboteq's Files Downloads section. 

Then to get the library into the library database, we need to select library->Add local library and then find the Roboteq Safety Features file and select Open.

This will add the library to the list of libraries.

Now you should be able to see the Roboteq_SISTEMA_SafetyFeatures library and the subystems on the left side of the libraries window. All the information regarding PL will appear on the lower left side of the window.

To load a safety subsystem from the library select the desired one and press load selection.

After loading the subsystems into the Safety function we can check the total PL rating of the safety function from the used subsystems, as well as the desired safety PL. We have set the Safety Function to be rated as PL d since we expect to conform with the lowest PL level which the two elements have. FBLGT – STO is PL e and SBS is rated at PL d.

The Safety PL we chose can be seen on the right side while below context we can see the PLr(requirement) and the PL of the system using FBLG STO function and SBS.

We hope this article serves as a valuable starting point on your journey toward enhancing safety in your AGVs.

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