Manoeuvring and reversing are the most frequent causes of accidents involving mobile machines used in open-cast and underground mining as well as on construction sites, in agriculture and forestry, and with municipal and special vehicles. By Manuel Fischer and Dr Anatoly Sherman.
Sensor-based automated systems are becoming increasingly important for vehicles used in mining, civil engineering, agriculture and forestry, and with construction, municipal and special vehicles. One area where sensors are used is to provide reliable systems that detect the risk of a collision and warn the driver.
The main driving force behind this development is the fact that a large number of collisions and accidents can be prevented if suitable technology is available to support the driver or machine operator. Active warning functions are not enough. The assistance system must also be able to distinguish between different objects depending on their importance for collision warning purposes. The particular challenges involved in these applications not only concern detecting and evaluating objects. The sensor solutions must also be designed to withstand the tough outdoor environments where the machines are used.
The Visionary-B active driver assistance system developed by SICK meets all of these requirements. Visionary-B consists of a 3D vision sensor suitable for outdoor use that identifies people and objects in the driver’s blind spot and issues a warning.
It also has another special feature; it has been designed as an active system. This means that as soon as an object appears within a defined detection zone, the system gives an audible and visual signal. In contrast to passive monitoring solutions, the driver does not need to look constantly at the monitor. Instead, he can concentrate on driving the vehicle, safe in the knowledge that the system will warn him in good time if a potentially critical situation occurs.
Plug-and-play 3D collision warnings
The role of the Visionary-B intelligent driver assistance system is to minimise the risk of collisions when mobile machines pull away, manoeuvre and turn, by monitoring the driver’s blind spot. The system consists of at least one sensor head, an evaluation unit, a 2D monitor and all the mechanical and electrical components needed for installation.
It is also a two-in-one solution because it combines an active 3D sensor for collision warnings with an integral 2D live camera. This means that the driver can also see a 2D live image and access recordings of the machine’s previous few hours of operation. When the system is installed at the height of between 1 and 2.4m, the detection angle of 105 degrees by 90 degrees enables it to cover an area behind the vehicle, not visible to the driver, that is 6m long and 4m wide.
The evaluation unit processes the 3D image data, assigns the objects to different classes based on the measurements, saves the recordings of the most recent period of operation, and uses intelligent algorithms that enable it to ignore any objects that are unlikely to cause a collision. At the same time, it transmits the live image and the alarm signals to the monitor in the machine’s cab, which issues collision warnings in the form of both audible and visual signals.
The stereoscopic principle and 3D snapshot technology
To ensure that the collision warning system is reliable and is accepted by drivers, it is essential that it consistently identifies hazards and can distinguish them from the machine’s normal working environment. The object detection system, which is based on the stereoscopic principle, is what makes this possible. It can identify the presence of people and objects and measure their distance from the vehicle. The cameras in the sensor head take images of the vehicle’s surroundings from slightly different positions.
The evaluation system combines these two perspectives and calculates the depth of the images, in other words, the third dimension. On the basis of the 3D image information, the 3D vision sensor can identify the width and height of the objects. This allows the system to distinguish between people and objects that could cause a collision and those that cannot – for example, curbstones and uneven ground.
SICK’s integral data evaluation unit reliably detects two classes of objects in an outdoor environment. The first class consists of smaller objects than those that make up the second class. Wide objects, such as walls, do not fall into the second class and are ignored for the purposes of this class. Configuring the system only to warn the driver about objects in class two is an ideal solution for narrow entrances or exits, for example, as it will prevent unnecessary and irritating warning signals from being issued.
The flexible configuration of alarm zones also makes it possible to distinguish between different types of warnings so that the driver can respond accordingly. This means that the Visionary-B system will not send faulty alarms. The driver is only notified if the situation is genuinely critical.
In addition to evaluating and classifying the objects that are detected, Visionary-B has a modular concept that enables the driver assistance system to be designed to suit the vehicle and the purpose it is used for. A range of different system configurations is available. These include variants with one sensor head for monitoring the direction the vehicle is travelling in, with two automatically alternating sensor heads for forward and backward movement, and with two sensor heads operating simultaneously that cover the area around and behind particularly large and bulky vehicles.
Designed for tough outdoor environments
The Visionary-B driver assistance system is highly rugged and is designed for outdoor use in the many different types of environments where mobile machines operate. The sensor housing has an IP69K enclosure rating and can withstand operating temperatures between -40 and +75 degrees Celsius. It also meets high standards of shock and vibration resistance.
The evaluation unit, which can often be installed in the safer setting of the driver’s cab, has an IP67 enclosure rating and a temperature range of -20 to +40 degrees Celsius. It has also been designed for long service life and can withstand challenging conditions. The evaluation unit uses algorithms that have been tested in practice to ensure that direct sunlight, rain, road surfaces that are damp and shiny and other environmental influences do not prevent the unit from detecting objects reliably or the system from issuing collision warnings.
A wide range of applications
Different types of mobile machines provide a variety of interesting applications for the Visionary- system. For example, the version of Visionary-B with two alternating sensor heads can be used in excavators to monitor the area behind the machine and the area to the side where the excavator’s arm blocks the driver’s view.
Front loaders, dump trucks and rollers are typical examples of mining and construction machines that can be operated much more safely using SICK’s active driver assistance system. In all types of environmental and light conditions, it can monitor areas in the machine’s direction of travel that are not visible to the driver. This reduces the risk of collisions and accidents to a minimum and also helps to prevent damage to the vehicle, together with the accompanying downtime and costly repairs.
Visionary-B is also a valuable addition to agricultural and forestry machines. It can detect possible hazards and accidents in good time and send an active warning to the driver. A reduction in the damage caused to vehicles also means shorter downtimes and high levels of availability, particularly during crucial times of the year, such as harvest. In municipal and special vehicles, for example, the trucks used for collecting recycled materials, Visionary-B constantly monitors the driver’s blind spot and provides active support when the vehicle is manoeuvring.
In addition to these examples, there are many other possible applications for this advanced driver assistance system. Visionary-B can be installed at any time in existing vehicle models. All the variants can be fitted by the manufacturer in new vehicles. They are also available as complete solutions for retrofitting or as dealer accessories and can easily be configured.
Manuel Fischer is Strategic Industry Manager Mobile Machines at SICK. Dr Anatoly Sherman is Head of Product Management – 3D Compact Systems at SICK.