Sensor trends for commercial vehicles and mobile machines

Pepperl+Fuchs manufactures extremely durable and resistant sensors for construction machines, agricultural and forestry machinery, communal vehicles, fork lift trucks and spreaders for all operating principles. The sensors meet demanding requirements for continuous outdoor use and offer features such as extended voltage ranges for on-board power supplies, oil-resistant connection lines, increased noise immunity, electromagnetic compatibility and e1 approval. The product portfolio includes M12, M18 and M30 series inductive sensors with a cylindrical design, which are also available in a stainless steel version, block-shaped sensors from the F33 series, type F99 inclination sensors for measuring ranges of 0 to 360° as well as absolute measuring inductive position and angle sensors from the PMI range. Magnetic rotary encoders and special safety encoders with functional safety features are available for special requirements relating to harsh ambient conditions and safety. Ultrasonic sensors can be used in a wide variety of applications such as agricultural machinery.

An ever growing number of electrical systems in modern commercial vehicles and mobile processing machines allow expensive machines to perform tasks with a high degree of efficiency, i.e. minimal energy costs, materials and time expenditure, but only when a sufficiently powerful sensor system is installed. However, the sensors are continually exposed to wind and adverse weather conditions and must therefore be exceptionally robust, durable and ensure an outstanding performance. This article provides an overview of the latest developments in sensor technology for the mobile equipment sector.

The different operating processes in commercial vehicles and mobile machines must run efficiently. Sensors play an important role here because they provide control units with information on rotary and tilt angles, the positions of grippers, pedals, forks and compression cylinders, detect the presence of attachments and much more. Reliability and quality are top of the requirements list for mobile equipment sensors because vehicles are often out on call and a service team cannot arrive on the scene within a few minutes like in factories. If the sensor fails, restricted emergency operation is then always possible. The devices are exposed to continuously changing influences such as heat, cold, rain, road salt, coastal air, corrosive chemicals as well as violent shaking and vibrations.

Non-contact functional principle comes up trumps

In addition to a host of improvements and further developments in vehicle technology, there is a clear trend towards non-contact functional principles in the sensor industry. Zero wear sensors have a long service life and increase the availability of equipment and machines. Whether inductive, capacitive, magnetic, optoelectronic or with ultrasonic technology, the Pepperl+Fuchs product range includes sensors suitable for any general or specialized application in the commercial vehicle and mobile equipment sectors.

The systems are characterized by features designed exclusively for the commercial vehicle and mobile equipment sectors, depending on the situation. The voltage range of 10...60 V supports standard on-board power supply voltages of 12 V, 24 V and 48 V, oil-resistant connection lines are available with wider cable diameters of 0.5 or 0.75 mm² and an emphasis is placed on better noise immunity and electromagnetic compatibility (EMC). For this reason, a number of main features from the mobile sensor range have e1 approval in line with mandatory guidelines for vehicles used on public roads, and require a general operating license.

Round and versatile

The inductive sensors with cylindrical design from the M12, M18 and M30 series are outstanding examples of perfect mobile equipment sensors. They have e1 approval, operate without making contact, are extremely resistant to extreme ambient conditions due to the inductive functional principle and degree of protection IP68 and IP69K, and are ideal for a wider temperature range of -40...+85 °C. Inductive sensors are used to monitor buckets and attachments on construction and agricultural machines such as diggers and make an important contribution to saving time and costs in an increasing number of applications that incorporate quick changeover systems. In harvesters they are used to retrieve information from different flaps, conveyors, harvesting units and locks, etc. The practical cylindrical shape allows for easy installation at different points around the machine. With an outstanding degree of noise immunity of 100 V/m, the sensors exceed the required value of 30 V/m by more than 300%. Type F33 inductive block-shaped sensors are used in the same way.

Also known as “metal face” sensors, inductive cylinders were developed specifically for machinery used mostly in aggressive environments and are also available in a stainless steel design. Suitable application areas include acid and chemical transportation vehicles, spreaders or port cranes exposed to salty humid sea air, waste disposal systems or applications where frequent treatments with high-pressure cleaners are essential.

For effortless “tightrope walks”

No less interesting are the type F99 inclination sensors. Also awarded e1 approval, they are suitable for all applications involving the monitoring of tilt angles on whole vehicles or the alignment of attachments, fork lift prongs, moving load platforms and so on. The F99 warns the operator when a digger is on uneven ground, cranes under load are positioned on an incline and fork lift trucks or fire trucks with an extended ladder are about to reach critical limit angles. The micromechanical measuring element with spring-mass system is, together with the evaluation electronics, embedded in a sturdy metal casing with degree of protection IP68/69K and can therefore be mounted directly on the vehicle without requiring an additional protective housing. The inclination sensors include analog outputs for 0...5 V or 4...20 mA as well as optional switching outputs and are available as one or two-axis versions with measuring ranges 0...360°.

Inductive detection of absolute distances and angles

Absolute measuring position and angle sensors from the PMI sensor range cover a wide application area in the mobile machine sector. The zero wear sensors are fully encapsulated and enclosed in a robust, tightly sealed housing. Configurable measurement and switching areas allow the user to adapt the sensors to a wide variety of tasks. They output a 4...20-mA current signal and can be additionally equipped with two optional switching outputs. The PMI360D records angles in the 0 to 360° range, while the length measuring systems of the F110 series have various detection ranges of up to 810 mm. Applications include monitoring the turning angle of the front and rear axles on agricultural machinery, for example, or the precision positioning of axle adjustments to distribute the total weight of the vehicle specifically over several tracks.

From safety rotary encoders to ultrasonic sensors

The Pepperl+Fuchs product range includes magnetic incremental rotary encoders and special safety rotary encoder as an alternative to the inductive rotary encoder. MNI40N magnetic rotary encoders are oil and water-resistant, extremely resistant to impacts and vibrations and can withstand temperatures up to 100 °C. The safety rotary encoders with certified functional safety are used in all applications with special mandatory safety requirements. They are suitable for systems from safety category SIL3 or lower according to IEC 61508 and satisfy performance level e as per ISO 13849.

Ultrasonic sensors offer some interesting application options for the commercial vehicle sector and mobile machines. The ultrasonic sensors from the 30GM series enable the guidance of driverless agricultural machinery along existing furrows. This solution is not only more accurate than other types of technology such as GPS, but is also less sensitive to contamination than camera-based systems, for example. The sensors are also ideal for monitoring the bar on field sprayers to maintain a defined distance between the spray nozzle and the ground and guarantee that fertilizer is spread evenly over uneven fields.

The need to identify certain machine parts on commercial vehicles such as attachments is a common requirement. IdentControl Compact identification systems are ideal for this because they are enclosed in a robust metal housing with degree of protection IP67 and fitted with M12 connections.

Summary

All in all, manufacturers of mobile machines can choose from a large selection of different sensor types and technologies from a single source. Needless to say, Pepperl+Fuchs supplies sensors on request with customized cable lengths and conventional market connectors from leading manufacturers such as Compagnie Deutsch, Tyco Electronics, Molex, JST and ITT.