Sensing the way forward to a mobile future
05 December 2018
Automated Guided Vehicles (AGVs) and their smaller cousins Automated Guided Carts (AGCs) promise to free more production environments from the slavery of fixed lines, conveyors and linear processes and make workflows more flexible.
In the Industry 4.0-enabled factories and warehouses of the future, autonomous, fast and flexible automated mobile vehicles of every kind will be the ‘pollinator bees’ that make the physical connections needed to – quite literally – deliver the goods.
Common sense
It is advances in sensing technology that are blazing this trail to a more mobile and driverless future. Sensors tell AGVs and AGCs where they are and where they are going. They give them eyes and intelligence to recognise the world around them, so that they can avoid collisions and keep people safe. They help vehicles to correctly identify and pick up their loads, then guide them into the warehouses space once they arrive at their destination.
To successfully integrate the right sensing technology into AGVs and AGCs, you need to use the same selection criteria as for any other sensor: Is it compact, robust and reliable in tough production environments? Does it offer connectivity to link to other factory systems to enable, for example, identification of real-time position, or to ensure traceability of goods or packages? Does it meet the correct safety certifications to fulfil the requirements of your risk assessment? Above all, does it facilitate availability and optimise productivity including easy set up and replacement?
Intelligent guides
Developments in laser scanning technology and LiDAR (Light Detection and Ranging) in particular have freed mobile vehicles from fixed pathways, enabling their routes to be more easily altered and even allowing vehicles to make their own decisions and move more independently.
LiDAR sensors and scanners use time-of-flight technology to measure the distances around a radius, in both horizontal and vertical planes. They enable navigation by identifying reflectors positioned along their path, or by profiling the contours of the environment as the vehicle travels through it.
Preventing collisions
When they are free-moving or self-driving, the need for AGV’s and AGC’s to recognise and react to their environment, and prevent collisions, becomes even more important. They need to be able to find their way by themselves and deal with virtually any kind of fixed or moving obstacle that may come their way.
Machine designers must equip vehicles with sensors that can identify a collision before it happens and provide the data needed for the AGV to take action and prevent it. The options available range from single beam long-distance photoelectric sensors, to fully-certified safety laser scanners.
Safety and productivity
Safety always goes hand in hand with productivity. So, crucially, advances in sensing technology for mobile vehicles are just as much about maximising productivity as they have to ensure high levels of safety.
We are all familiar with the concept of an AGV that will stop if you step into its path. But how far ahead it can see you, how quickly it responds, and whether it needs to stop altogether and be restarted, or just slow down as it approaches you, will make a difference to the speed it can travel and how productive it can be.
AGVs & AGCs simply would not have become the integral part of production and logistics that they are today without the Safety Laser Scanner. The technology has advanced to enable vehicles to move at greater speeds, to overcome space restrictions in factory or warehouse environments, and optimise workflow efficiency and productivity – all, of course, without compromising the safety of personnel.
SICK’s safeHDDM scanning technology has set new standards for safety laser scanners by combining a compact design with a wide scanning range. Used in safety laser scanners like the SICK microScan3, it enables mobile vehicles to move at greater speeds and overcome space restrictions in factory and warehouse environments.
We can integrate the SICK microScan3 with encoders on an AGV/AGC to achieve safe motion control. Rather than emergency stopping when an object is detected, warning fields can be set to ensure that AGV/AGC’s can slow down and speed up with respect distances from people and object.
Why size matters
One useful development in safety laser scanner capability has been the ability to scan longer protective fields. The maximum protective field that a scanner can facilitate is an important feature to consider if you design and build AGVs and AGCs – or if you want to purchase one. However, field size alone should not be the deciding factor. The response times of the safety devices and associated control system are also very important values to consider and not taking care to ensure these values are reasonable can have a huge impact on an application.
An AGV or AGC with a smaller protective field footprint is better suited to high output efficiency and space utilisation in a modern production environment. When specifying a safety laser scanner, it is more important to consider the total response time and detection robustness to ensure that protective fields can be kept to a minimum.
Rapid system safety response times in an integrated safety system, enhanced by devices such as safety encoders to control acceleration and braking, can achieve the required safety in AGV operation in a smaller footprint.
Keeping the protective field as small as possible is an advantage where AGV’s need to work in closer proximity to each other, to work with smaller clearance spaces and with reduced stoppages.
Ending stop-start frustrations
The SICK Safe AGV Forklift solves a common stop-start frustration that slows operation and leads to wear and tear of Automated Guided Vehicles (AGVs) fitting with a forklift: When the protective laser scanning fields are infringed because the forks are down, the AGV must be brought to a safe stop.
This PLd/SIL2-certified safety solution enables a driverless forklift to continue to operate productively in an automated factory or logistics environment, even when the forks are in the load carrying position.
The SICK Safe AGV Forklift uses two SICK safety laser scanners providing protective detection fields in front and behind the vehicle, integrated via a SICK Flexi Soft controller with a SICK DFS60S Pro encoder to monitor the speed of the vehicle. When the scanning field is obscured by the forks during loading and unloading, the AGV can continue to proceed at a safe speed, even when the forks are down and loaded.
The SICK scanners operate a warning detection field as well as a protective stop field, so that the AGV slows when objects are sensed at a distance, reducing the wear and downtime associated with constant start/stop operation.
When specifying sensors for AGVS and AGCs, it’s wise to consult an experienced and specialist manufacturer to be confident of the correct choice. At SICK our experts are waiting to guide you.
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