Load detection and 3D collision warning for mobile intralogistics

Collision avoidance in automated guided vehicle systems (AGV) and mobile platforms, and rear area monitoring in forklifts or heavy trucks are just two of the many mobile intralogistics tasks that can be handled simply and efficiently using the Visionary-T DT configurable 3D vision sensor from SICK, write Michael Dold, strategic industry manager of Industrial Vehicles, Global Industry Center Logistics Automation, and Dr. Anatoly Sherman, head of business Unit 3D Compact Systems, Product Management & Applications Engineering.

In the case of particularly challenging applications, such as the automated detection of cargo or load carriers by automated guided vehicles (AGV), the Visionary-T AP, which can be programmed using the SICK AppSpace eco-system, offers a whole host of individual solutions.

Even the intralogistics sector has succumbed to the full force of the fourth industrial revolution – or Industry 4.0 – and the increasing digitalisation of its processes. AGVs, AGV systems, and mobile robots are playing an ever more essential role in this trend toward autonomous material flows, with flexibility, reliability, availability, and productivity being the major contributing factors in the efficient use of these vehicles. This is why it is so essential to detect potential faults as early as possible and respond to them appropriately via the vehicle control system.

Hazards often lurk in the third dimension
Electro-sensitive protective devices such as the safety-oriented 2D LiDAR sensors (2D laser scanners) offer the necessary machine reliability and personal safety. These monitor the travel paths and movement areas of the vehicles and are available in various sizes, with various scanning ranges and functionalities for virtually any vehicle concept and area of application. In many cases, the vehicles feature localisation and navigation functions to ensure they can bypass any detected obstacles without intervention or even avoid alternative routes.

It is features such as these that contribute toward the certified safety of AGV systems and similar in 2D. But when it comes to efficient vehicle and system operation, the third dimension cannot be overlooked since not all collision hazards lurk at floor level: Pallets, pallet loads, and raised load-carrying units of manned forklift trucks can all protrude into travel paths at various heights. Crane hooks may be suspended at vehicle or loading height above the path ahead. A crane trolley could start lowering a suspended load from above. Bulky or oversized parts may unintentionally rotate into the pathway while being handled. All of these possibilities can lead to collisions, resulting in damage to the vehicle or load that could seriously compromise the smooth operation of mobile intralogistics and the associated production processes. The Visionary-T 3D vision sensors are capable of offering reliable collision warnings for highly automated vehicles. In manned forklifts and heavy trucks with areas that are difficult or even impossible to see from the driver’s seat, they prove to be helpful blind spot monitors.

Visionary-T DT: Configurable 3D vision sensor with integrated evaluation
The Visionary-T DT is a 3D vision sensor in an industrial-grade IP67 housing with an integration-friendly one-box design. The sensor offers a solid working distance and uses 3D time-of-flight measurement as its detection principle. This involves the sensor sending light signals toward the measuring object in the direction of travel of the vehicle. Objects in the field of vision of the sensor reflect the light; for every pixel received, the distance to these objects can then be calculated in the sensor via the phase shift. The depth information of the several thousand individually recorded pixels is combined into a single image to create a three-dimensional real-time distance image of the entire area – a 3D snapshot. Each of these snapshots contains more than 25,000 distance values. The Visionary-T DT takes up to 50 3D images per second in this way, making it possible to detect potential hazards for an AGV system in no time at all. The 3D data is processed directly in the sensor without involving any external computer support or creating vehicle communication issues. If required, the evaluation of the Visionary-T DT can generate sensor responses directly and initiate actions via the digital outputs or the Ethernet-based data interface. These include the triggering of alarms and alerts, the automated reduction of speed, and a vehicle stop when encountering an obstacle. Depending on the situation, it is even possible to switch between multiple sensor configurations via a number of discrete inputs. The 3D measurement data in the sensor also provides essential depth information that can be useful for assisting the AGV system to control the navigation. This can be in the form of raw data, data that has been pre-processed to suit the specific application, or pre-evaluated measurement data.

Programmable Visionary-T AP enhances individual degree of freedom
With more than 30 different integrated application configurations to choose from, the Visionary-T DT already offers a high level of flexibility for a whole host of application scenarios. But when it comes to more individual or even groundbreaking tasks, this is where the Visionary-T AP comes into its own as the programmable variant of the 3D vision sensor. This forms part of the SICK AppSpace eco-system, which SICK has used to open up the software options for sensors with incredibly diverse physical operating principles and technologies and make them programmable. As a result, even external users and integrators can tailor the functionalities of Visionary-T AP to suit their individual needs and circumstances by developing apps of their own or integrating appropriate apps available in the SICK AppPool. The first AGV system tasks to be implemented by programming key apps with the Visionary-T AP from SICK are pallet detection and the detection of trolley corners. The measured XYZ coordinates of the programmable 3D vision sensor make it possible to perform tasks such as lowering and lifting an empty or loaded pallet independently using the fork on an automated pallet truck. It is also possible to check the contour of the load for protrusions or excess height to ensure reliable transportation and seamless transition or storage. A similar app that allows small mobile platforms to be lowered and lifted independently based on the position of transport trolley corners is already in the field testing phase. For both applications, SICK is offering its customers ready-made key apps as a complete software solution. Going forward, there will be yet more key apps for a whole host of different applications,  whether these are based on the current Visionary-T variants or designed for high-resolution Visionary-T sensors in the “Pro” product line.

From collision warnings and navigation support through to load carrier detection, the Visionary-T 3D vision sensors offer reliable 3D measurement data around the clock. This essential information about the surrounding environment facilitates collision-free, flexible, highly available, and efficient operation of AGV systems and other vehicles within intralogistics plants.

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