Winter Operations: Remote Control Clearance

While automation and robotics are an increasing facet of winter operations, a recent field trial in Germany using a fleet of remote controlled vehicles for airfield clearance, has opened up fresh possibilities. Gary Mason reports.

The winter operations equipment used by large airports to clear airfields during the winter season is essentially plant machinery. The drivers of these vehicles need to be well trained for the specialist tasks they undertake and given the increasing complexity and sophistication of runway clearance and de-icing, it is not a job that can be left for trainees or casual staff.

This is because the airside safety and environmental consequences of human error when operating these big vehicles are too significant to take a risk with staff who are not familiar with them. But given that winter operations at airfields only takes place for a few months each year or not at all if there is no snow, there could be substantial benefits gained from increasing the level of automation and use of robotics in this job.

To a certain extent this is already happening with modern snow blowing and de-icing vehicles. The level of automation in operating the vehicle is that much higher which means that inexperienced drivers can be trained to use them extremely quickly whether they are working at civilian airports or military bases and whether they are dedicated airport personnel, military personnel or third party winter workers. For example the new Supra 5002 snow blowers being used at Heathrow have an automated drive.

But a recent field trial involving German airport operator Fraport and Daimler AG has successfully tested the concept of using robot vehicles for runway clearance.

This potential solution for the future use of automated commercial vehicles follows the successful demonstration of the Highway Pilot and Highway Pilot Connect systems, the latter making the concept of truck platooning possible.

On the site of the former Pferdsfeld airbase, the pilot demonstrated the practical application of automated snow removal operations at airports based on a specific customer requirement.

Martin Daum, the Daimler AG Board of Management member responsible for Daimler Trucks, emphasises: “We are not just talking about new technologies, we are bringing them onto the road. Step by step we are developing our very latest assistance systems even further – with a view to automated driving. We are currently working on the implementation of two specific use cases: Firstly automated driving in quite normal traffic on motorways – with the clear aim of relieving driver workload and significantly improving safety. And secondly driverless operation in enclosed areas to significantly improve productivity such as today’s demonstration of automated snow clearance on an airfield.”

During the field trial, which was called “Automated Airfield Ground Maintenance“ (AAGM), four Mercedes-Benz Arocs tractor units demonstrated automated airfield clearing in a remote-controlled convoy. According to Fraport AG and Daimler the benefits of using such a system are clear.  Airfield clearances are hard to predict and thus difficult to plan, especially in winter. This makes snow removal units operated with pinpoint precision by a single vehicle operator to remove snow from runways especially crucial when extreme weather strikes without warning, and they require no additional vehicle and staff scheduling.

The project was the result of close cooperation between Lab1886, the Daimler innovation arm and Fraport AG.

“The mission of Lab1886 is to develop new innovative business models for Daimler. The Fraport project is a great example in this regard. It shows how we bring together innovations with specific customer needs to develop new markets“, says Susanne Hahn, Head of Lab1886.

Mathias Dudek, head of Infrastructural Facility Management at Fraport AG said: “As one of the first airports worldwide, we are pleased to be contributing our know-how to this innovative project. It enables us to examine autonomous control of heavy winter service equipment in the especially challenging winter conditions of an airport. We hope to obtain findings that will help us to plan the future deployment of equipment even more precisely and efficiently under sudden wintry conditions. Our commitment once again underlines the role of Fraport AG as an innovation driver in a wide range of areas.”

Based in Frankfurt/Main, Fraport AG operates one of the world’s largest air traffic hubs. The objective of the joint testing activities is the implementation of state-of-the-art telematics-based vehicle control technology in areas not accessible to the public. This is one of the key aspects in which the new application differs from autonomous driving developed for practical testing by Daimler to date. The Highway Pilot and the Highway Pilot Connect system presented for platooning are designed for use on public roads.

In addition to a comprehensive set of requirements on automated operating machines, Fraport also supplied the snow removal equipment for the trial. Four sweeper blowers of the kind already in operation today were used as semitrailers and towed by conventional Mercedes-Benz tractor units.

Premiere for the “Remote Truck Interface” (RTI)

The four Arocs test vehicles were equipped with the new Remote Truck Interface (RTI) for remotely controlling vehicle functions and exchanging data. The RTI is the centrepiece of the new technology, for which Daimler can draw on a significant pool of knowledge and engineering from projects such as the advanced Highway Pilot and Highway Pilot Connect systems.

All vehicles are fully interlinked via the RTI by means of telematic systems, all operate automated and all are able to lead or follow in the vehicle convoy. Specifically, this means that a convoy leader chooses a random unit from a fleet of available semitrailer combinations and defines this as the “lead truck”. He then uses a control panel to define the number and sequence of the other convoy vehicles, and conducts a pre-operation inspection of his and all other semitrailer combinations.

All vehicles are equipped with dual GPS tracking (DGPS) and state-of-the-art vehicle-to-vehicle communication (V2V communication) technology.

In addition, the interplay of the RTI and the remote control unit provides fast and secure data exchange among vehicles, the developers claim. To make this work in real time, a full data exchange between the vehicles and the main control unit of the RTI takes place every 0.1 seconds. The transmissions in the area of V2V communication are based on the “Digital Short Range Communication DSRC“ technology.

Looking ahead: automated driving offers a wide range of possible applications

The automated snow removal convoy comprises four vehicles during the test phase and can be expanded to up to 14 units. It paves the way for further applications. In addition to other airports that have already signalled interest in such precision work machines for automated runway maintenance, solutions for a wide variety of applications are feasible.

“This opens up new possibilities for our customers: High-precision manoeuvring procedures of conventional trucks, remotely controlled by the driver outside the cab – for example, positioned at the rear of the vehicle with a perfect view of the manoeuvres – are possible, as is unmanned driving in mines, at container terminals or other closed-off sites”, says Martin Zeilinger, Head of Advanced Engineering at Daimler Trucks.

The tasks of the automated Arocs in AAGM (Automated Airfield Ground Maintenance) test operations

In the case of the demonstration of the Arocs tractor units, the Remote Truck Interface connects the vehicle with the outside world. The control functions for track guidance and operation of the convoy are housed in additional external control units such as the track computer, the operating panel and the wireless interface. Specifically this means that the automated Arocs trucks are able to perform the following functions:

  • Control: engine start/stop
  • Control: parking brake
  • Vehicle lateral control: steering
  • Vehicle longitudinal control: engine control (throttling up and down)
  • Vehicle longitudinal control: service brake
  • Powertrain management: transmission (engage start-off gear, all gear changes, engage neutral)
  • Powertrain management: activation and deactivation of the differential locks
  • Peripherals: lights including turn indicators, rotating beacons
  • Special functions: body control; here: control of the mounted sweeper blower

The RTI control unit allows actuation of all connected vehicle functions via an interface (CAN). Remote control is thus possible by integrating a wireless interface into the CAN.

“An important component of the RTI control unit is the integrated safety concept. This means that all vehicle functions are monitored. The safety routine is executed as soon as an error occurs. In this way we can ensure that the vehicles can be stopped safely and quickly if needed, and can then simply be operated manually”, Zeilinger adds.

The test operations: snow removal equipment must offer highly flexible responses

In the past, airport operators have had to keep the required removal and cleaning equipment in an operational stand-by condition. The lead times for relatively rare and usually short-lived bad weather periods tie up capacity.

On the other hand, an airfield requires consistent and thorough clearing operations even when just a little bit of snow covers the ground. On such sites, the snow must be cleared to one side over a width of up to 60 metres in a single pass. In the case of Frankfurt Airport today, up to 14 vehicles drive in a convoy with the appropriate overlap.

This means the snow is “passed on” from the front to the rear from one vehicle to the next. As a result, the snow load increases from vehicle to vehicle, and the performance requirement for the individual snow removal units rises sharply from front to rear. Furthermore, the staggered driving also makes high-precision guidance crucial for the quality of the clearing pattern. All this necessitates highly dissimilar requirements on the performance of each snow removal vehicle.

Efficient operations thanks to automated snow removal machines

In the case of Frankfurt-Main airport, the convoy must keep the runways and taxiways free from snow and ice as a precisely staggered formation. To date, snow clearance machines have worked their way along metre by metre under poor visibility conditions in darkness and fog, with snow constantly being thrown up by the vehicles driving ahead.

The poor visibility often leads to increasing distances between vehicles, opening up the convoy and extending the time it takes to clear a runway. Moreover, poor visibility can lead to the outer vehicles damaging the runway marker lights, which are very expensive to repair.

In the test of the autonomously operating snow removal trucks of Daimler, a predefined snow removal programme – under the constant control of a convoy leader – specifies the routes, direction and speed. The person in the lead vehicle of the removal convoy in charge of the demanding task enjoys relatively good visibility of the swaths to be cleared ahead of the lead and the trailing vehicles.

The swaths to be cleared are predefined with the goal of a high-precision clearing trajectory. This means the routes to be driven are always specified cartographically and are followed with pinpoint precision thanks to a differential GPS system – accuracy: three centimetres – by the lead vehicle as well as the other convoy vehicles thanks to constant target/actual comparisons.

A high level of flexibility is also a must for snow clearance operations on airfields. That is why the convoy leader – owing to suddenly identified and then immediately required deviations from the digitally specified clearing path – is able to take over the routing personally at any time.

To this end, the convoy leader has the classic controls – steering wheel, accelerator and brake pedal – at his disposal in each Arocs – and thereby full control over the vehicle. The trailing vehicles then immediately and fully automatically adopt the target paths resulting for them from the change of the route of “vehicle 1”.

All-wheel drive Arocs 2045 AS 4×4 as the basis for the snow-clearing semitrailer combination

The prototype convoy from Advance Engineering presented now comprises four individual vehicles initially. The basis is provided by all-wheel-drive Mercedes-Benz Arocs 2045 AS production tractor units from the robust Grounder product range, equipped with the latest OM 470 LA engine generation certified to Euro VI standards with an output of 315 kW (428 hp) and producing 2100 Nm of torque. At a brisk speed, most of the mass of snow is thrown to the side by a fully hydraulic, three-section snow plough measuring eight metres in width.

The finishing surface clearing touches are carried out by a sweeper blower. It is towed as a semitrailer and powered independently of the tractor unit by a six-cylinder engine from Mercedes-Benz installed at the rear of the semitrailer.

The entire tractor/semi-trailer combination is 23 metres long and weighs 25 tonnes in operational condition. The tractor unit, which was reinforced in the area of the snow plough mounts, accounts for about ten tonnes, the plough blade adds two tonnes to the total weight, the semi-trailer with the sweeper blower has a gross weight of 13 tonnes.

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