Chassis Layout of an Autonomous Truck
A Transportation Concept for the Mining Industry
Johannes Dahl Gabriél-André Grönvik
Mechanical Engineering, masters level 2016
Luleå University of Technology
Department of Engineering Sciences and Mathematics
Preface
This thesis was performed by Johannes Dahl and Gabriél-André Grönvik at Scania. Johannes was studying Mechanical Engineering at Luleå University of Technology and has experience in product development and great knowledge in machine design and components. Gabriél was studying Vehicle Engineering at KTH and has competence in vehicle concepts, components and dynamics.
The authors want to thank the supervisors Jenny Jerrelind at KTH, Torbjörn Lindbäck at LTU and Måns Lundberg at Scania for their support and advices. We also want to thank other personnel at Scania; our boss Christian Lauffs, Eric Falkgrim and Jan Dellrud for running this project, Mikael Wågberg and Daniel Bergqvist for sharing their expertise about the mining industry and everyone that we have been in contact with at Scania for exchanging many great ideas. Finally, we want to thank all staff at RTMX for great support, good advice and involvement.
Abstract
Autonomous driving might increase safety and profitability of trucks in many applications. The mining industry, with its enclosed and controlled areas, is ideal for early implementation of autonomous solutions. The possibility of increased productivity, profitability and safety for the mining industry and the mining area as a ground for development could, through collaboration, result in many benefits for both mining companies and truck manufactures.
Scania must investigate how these autonomous vehicles should be constructed. The project goal is thereby to develop a chassis layout concept for an autonomous truck. The concept should improve profitability and safety for transportation of materials within the mining industry while minimizing the introduction of new components to Scania.
The chosen approach is based on the Ulrich & Eppinger method for product development including generation and selection of concepts. Product requirements were specified from identified customer needs. The generated concepts were evaluated against these requirements and comparisons were performed with weighted matrices.
Some benefits of the final chassis layout concept are a higher load carrying capacity, more robust component placement and higher ground clearance. The vehicle concept would also be able to operate in underground mines with low roof clearance which could open new market segments for Scania. However, the concept requires development to gain higher performance on load carrying components in the chassis front.
The suggested concept shows that Scania could build and deliver autonomous mining vehicles with optimized chassis layouts based on Scania’s existing components within a near future.
Keywords
Autonomous, cab-less, driver-less, dump truck, chassis layout, hauling, mining transportation, underground mines, open-pit mines, mining industry.
Sammanfattning
Autonom körning kan öka säkerheten och lönsamheten för lastbilar i många applikationer.
Gruvindustin, med dess avgränsade och kontrollerade områden, är ideal för tidig implementation av autonoma lösningar. Möjligheten till ökad produktivitet, lönsamhet och säkerhet med gruvindustrin och gruvområderna som plats för utveckling kan, genom samarbete, resultera i många fördelar för både gruvföretagen och lastbilstillverkarna.
Scania måste därmed undersöka hur dessa autonoma fordon bör konstrueras. Projektmålet är därmed att ta fram ett koncept på en chassilayout för en autonom lastbil. Konceptet bör öka lönsamheten och säkerheten för transport av material inom gruvindustrin medan introduktionen av, för Scania, nya komponenter minimeras.
Det valda angreppssättet är baserat på Ulrich & Eppingers metod för produktutveckling inkluderande generering och urval av koncept. Produktkraven specificerades utifrån de identifierade kundkraven. De framtagna koncepten utvärderades mot dessa krav och jämförelser genomfördes med viktade matriser.
Några fördelar hos det slutgiltiga chassilayoutskonceptet är högre lastkapacitet, mer robust komponentplacering och högre markfri gång. Fordonskonceptet har även möjlighet att köra i underjordiska gruvor med låg takhöjd vilket kan öppna upp nya marknadssegment för Scania.
Dock kräver konceptet utveckling för att nå högre prestanda hos lastbärande komponenter i främre chassi.
Det föreslagna konceptet visar att Scania skulle kunna bygga och leverera autonoma gruvbilar med optimerad chassilayout baserat på Scanias existerande komponenter inom en snar framtid.
Nyckelord
Autonom, hyttlös, förarlös, gruvbil, chassilayout, gruvtransport, underjordsgruvor, dagbrott, gruvindustri.
Contents
1 Background ... 1
2 Problem formulation ... 3
2.1 Project aim and goals ... 3
2.2 Project delimitations ... 3
2.3 Risk analysis ... 3
3 Approach ... 5
4 Market analysis ... 7
4.1 The mining industry ... 7
4.2 Operating conditions ... 10
4.3 Benchmarking ... 11
4.4 Customer needs ... 20
4.5 Legal requirements ... 20
4.6 Market opportunities ... 20
5 Product requirements ... 23
5.1 Mission statement ... 23
5.2 Function degradation ... 23
5.3 Product specification ... 25
6 Concept design ... 27
6.1 Technical specification ... 27
6.2 Wheel configuration and powertrain ... 28
6.3 First concept selection ... 35
6.4 Bodywork and main components ... 37
6.5 Second concept selection ... 48
6.6 Finalizing ... 49
7 Final concept ... 51
8 Suggestions on new parts and modifications ... 55
9 Discussion and conclusions ... 57
10 Future work ... 59 Appendix A ... A.1 Appendix B ... B.1 Appendix C ... C.1 Appendix D ... E.1 Appendix E ... E.1 Appendix F ... F.1
List of figures
Figure 1: Scheme of general product development process. ... 5
Figure 2: Final workflow. ... 6
Figure 3: Open pit mine [5]. ... 7
Figure 4: Schematic of an underground mine [6]. ... 8
Figure 5: Transportation solution within the mining industry. ... 8
Figure 6: Open pit mine material flow [7]. ... 9
Figure 7: Value creation of mining transportation tasks. ... 11
Figure 8: Rigid haul tuck [15]. ... 12
Figure 9: Articulated haulers, (a) underground use [16], (b) over-ground use [15]. ... 12
Figure 10: Scania dump truck [17]. ... 13
Figure 11: EcoTwin platooning [20]. ... 14
Figure 12: Mercedes-Benz 2025 highway pilot concept [23]. ... 14
Figure 13: Komatsu autonomous haulage system in Australia [27]. ... 15
Figure 14: Function degradation including eleven different sub-categories. ... 23
Figure 15: Reference truck used in Vehicle Optimizer. ... 28
Figure 16: Cab-less truck with forward extended body. ... 29
Figure 17: Cab-less truck with stronger front axles. ... 30
Figure 18: Cab-less truck with shortened axle distances. ... 30
Figure 19: Cab-less truck with greater overhang... 31
Figure 20: Extended, cab-less truck with support axle and centred bogie. ... 31
Figure 21: Cab-less truck with front extended frame and steering axles. ... 32
Figure 22: Axle ground clearance. ... 34
Figure 23: Ground clearance of frame mounted components. ... 34
Figure 24: Wheel configuration and suspensions. ... 35
Figure 25: First suggestion of performance step. ... 36
Figure 26: Second suggestion of performance step. ... 36
Figure 27: Piston unloading material [32]. ... 37
Figure 28: Tipping the whole truck [33]. ... 37
Figure 29: Falling object protection system [35]... 38
Figure 30: High air intake, forward position. ... 39
Figure 31: High air intake, angled forward position. ... 39
Figure 32: Silencer positions, illustrated by large silencers. ... 40
Figure 33: 200G Fuel tanks right and left hand position. ... 41
Figure 34: 300G Fuel tank left hand position. ... 42
Figure 35: AdBlue tank positions. ... 42
Figure 36: Front axel air tanks positiones. ... 43
Figure 37: Rear axle air tanks positiones. ... 43
Figure 38: Air processing system, left corner position. ... 44
Figure 39: Horn, repositioned left corner. ... 44
Figure 40: Steering servo left and right hand positon. ... 45
Figure 41: Engine cover from R-cab floor. ... 46
Figure 42: Large engine cooler... 46
Figure 43: Front interface layout with cut corners. ... 47
Figure 44: Washer tank, left corner position. ... 47
Figure 45: Example truck specified with parts from concept selection two... 48
Figure 46: Final concept. ... 51
List of tables
Table 1: Risk analysis. ... 4
Table 2: Tasks of Planning and Concept development phase in original method. ... 5
Table 3: Truck components divided into three categories, phase 1, phase 2 and phase 3. ... 24
Table 4: Summary of product specification. ... 25
1 Background
Scania has provided heavy trucks for the transport industry for the last 120 years and during the last 15 years they have been involved in the mining industry. This worldwide mining industry, found in deserts to jungles and arctic settings, is known for its rough and harsh environment [1].
Scania is currently delivering manually driven trucks for the transportation of ore and waste in the mining industry. With the constant competition in the vehicle industry it is important to find new, more cost efficient, solutions to transportation. An autonomous vehicle has the potential to make the transportation more efficient since it does not require a driver. Hence the vehicle does not require any cab which enables a variety of chassis layouts rather different from the standard Scania trucks of today. The new degrees of freedom enable new, possibly more efficient and flexible, vehicle concepts that may increase profitability for the customer. It is thereby important for Scania to explore these possibilities and investigate how and to which extent they could include these vehicles in their portfolio. Scania has therefore employed five groups of master thesis students within the subjects; chassis layout, communication, sensors vision, sensor placement and lighting. The students will cooperate with the aim to develop a vehicle concept of an autonomous mine transportation vehicle.
2 Problem formulation
2.1 Project aim and goals
The overall question, leading to this project, was how Scania should include driverless, cab- less, efficient and flexible autonomous vehicles with the existing Scania bygglada in mind.
Where the bygglada is Scania’s modular system including all truck components with several performance steps. A suitable environment for developing autonomous trucks would be an enclosed and controlled area such as a mine. Accordingly, the projects main aim was to investigate how a chassis layout for an autonomous mining vehicle for transportation of ore and waste can be realized with Scania’s existing bygglada. The secondary aim was to give suggestions of modifications of existing components or new components that could be added to the bygglada for future concept development.
The result will be supporting decisions regarding Scania’s future development of autonomous trucks within the mining industry. The project will also guide future concept development.
The project goal was to develop a vehicle with better performance than the conventional solutions on the market today, such as higher availability, flexibility, lower environmental impact, greater personnel safety and be more profitable for the customer. The vehicle should also be able to equip different bodyworks.
2.2 Project delimitations
The project was performed by two engineer students in 20 weeks, see Appendix A, during the spring of 2016.
The chassis should be designed for the mining industry based on Scania’s bygglada. It should also originate from the current standard frame width, frame cross section and frame bend angle used by Scania today as well as the existing powertrain. These components are crucial to the modularity of Scania’s bygglada and have been a great investment. The concepts should be developed from the customer needs and applications identified in the pre-study ”Förstudie om autonoma fordon i gruvindustrin” by Alina Ekström and Josephine Sörensen [2]. As well as requirements from the other master thesis groups.
The autonomous vehicle is intended to operate within demarcated and controlled areas, and not on public roads. However, future mining vehicles might operate in both areas and the possibility to drive on public roads is therefore advantageous.
2.3 Risk analysis
In order to prevent unnecessary harm to the project a risk analysis was made, shown in Table 1 below. This analysis displays identified risks during the project. Prevention plans are stated in order to prevent the risks from occurring. There are also action plans if one of the risk were to occur. The possible damage is rated from 1-5, where 1 is a minor disturbance and 5 is a huge setback. The probability is also rated from 1-5, where 1 is very unlikely and 5 is very likely.
The score is a product of damage multiplied with probability and ranges from 1-25, where anything above 10 is a risk that has to be solved. Our analysis shows that none of the risks are scored high enough to make changes in the approach or the problem formulation. However, if
a risk would have emerged during the project with a higher score than 10 it would have been solved to ensure that the project runs with as little risks as possible.
Table 1: Risk analysis.
Risk Damage Probability Score Prevention plan Action plan
Data loss 5 1 5 Keeping data on Scania network Restore as much as
possible, rewrite Missed deadlines 2 3 6 Continuous follow-up of GANTT Reschedule
Illness - Minor 1 3 3 - Communication and
rescheduling
Illness - Major 5 1 5 - Change of scope and
goal, contact mentor
Lack of competence 1 5 5 Literature study Consult experts within
the area Lack of project
resources 4 2 8 Continuous follow-up of GANTT Revise scope and goal,
contact mentor
3 Approach
The final concept was to be generated through a modified version of the general product design process described in “Product Design and Development” [3]. The process, shown in Figure 1, consist of six phases; Planning, Concept development, System level design, Detailed design, Testing and refinement and Production ramp-up. Since the project result, as specified in 2.1 Project aim and goals, should be a final concept only the two first phases of the design process will be used.
Figure 1: Scheme of general product development process.
The two phases can be broken down in to four main areas; market, design, manufacturing and other functions according to Table 2.
Table 2: Tasks of Planning and Concept development phase in original method.
Planning Concept development
Marketing
Articulate market opportunity.
Define market segments. Collect customer needs.
Identify lead users.
Identify competitive products.
Design
Consider product platform and architecture.
Assess new technologies.
Investigate feasibility of product concepts.
Develop industrial design concepts.
Build and test experimental prototypes.
Develop product architecture.
Manufacturing
Identify production constrains.
Set supply chain strategy Estimate manufacturing cost
Assess production feasibility.
Other functions
Research: Demonstrate available technologies.
Finance: Provide planning goals.
General management: Allocate project resources.
Finance: Facilitate economic analysis.
Legal: Investigate patent issues.
Planing Concept
development
System level design
Detailed design
Testing and refinement
Production ramp-up
Financial, legal and supply strategies are outside the scope of this project. Market opportunities and segments as well as customer needs has been identified in the pre-study “Förstudie om Autonoma Fordon I Gruvindustrin” [2]. Though both were considered as requiring further investigation, or at least confirmation since the pre-study was done in 2012. The market and customer demands might have changed during the past four years. The remaining tasks forms the design process and was ordered into six phases as shown in Figure 2.
Figure 2: Final workflow.
The first step in the project was to state a project scope and an initial plan of the project resources. The second step was then to understand and verify the customer needs, operating environment and conditions, demonstrate available technologies through benchmarking and document related technologies. A comparison between the potential of the autonomous vehicle and the conventional solutions could then be performed. This would give the possibility to find areas where the autonomous vehicle is competitive.
Based on the identified situations, where the autonomous vehicle has an advantage, a requirement specification was created to define the vehicle. It is also against this specification that the vehicle was verified. The chassis layout was then developed during three phases, assessing different parts of the vehicle concept. The overall vehicle concept was developed through iteration and the different subsystems were chosen by narrowing down developed concepts through selection. The selections were done based on related literature and consultancy from experts at Scania. The final concept is the result of the overall layout concept and the concepts chosen for each subsystem. Suggestions on new components or changes to existing components were also made.
In order to achieve the goal, the following questions were answered:
What are the customer needs regarding transportation of ore and waste?
How are conventional ore and waste transportation vehicles designed and used today?
What potential is there in autonomous mining vehicles?
What is required of the vehicle?
How is the set of requirements effecting the vehicle chassis layout?
How can the layout be optimized to the new circumstances?
What new components or modifications to existing components should be included in the chassis layout?
How is maximum customer value achieved?
What are the benefits of a new layout?
4 Market analysis
The market analysis consists of three main sections. An overall description of the mining industry describing the different mine types and material flows. A definition of the operating area and identification of operating conditions addressed by the project. A benchmark of competitive solutions and solutions available at Scania. The benchmarking consisted of five main areas;
Common transportation concepts within the mining industry.
Components from Scania’s bygglada relevant for heavy-duty dump trucks.
Competitive solutions on specific problems and subsystems.
Scania’s autonomous trucks today.
Competitors’ development of autonomous trucks.
The market analysis also identifies customer needs and relevant legal requirements. Finally, Scania’s position on the market and future market opportunities are discussed.
4.1 The mining industry
The mining industry spans many countries all over the world such as South Africa, Russia, Australia, Ukraine, Guinea and Sweden. There are different mining strategies including several transportations of waste and ore in an environment that is harsh and dangerous for both workers and vehicles.
4.1.1 Mining strategies
There are two main types of mines, open pit mines and underground mines. When choosing which type of mine to operate there are many factors to take into account; size, shape and depth of the deposit, rock conditions, productivity, and costs are a few examples. An open pit mine is commonly used when excavating a near surface deposit [4]. The ore is excavated by using horizontal benches to get deeper into the ground, see Figure 3.
Figure 3: Open pit mine [5].
Underground mining is used if the ore deposit is shaped in a way that isn’t beneficial for open- pit mining or if surface mining has gone deep enough that underground mining is the next logical step to keep production rates high and costs low [4]. A schematic of an underground mine can be seen in Figure 4.
Figure 4: Schematic of an underground mine [6].
The material flow in a mine vary depending on what is extracted, the mines location, if it is an open pit or underground mine as well as the strategies chosen by the mining company. An illustrated overview of the transports within a mine can be seen in Figure 5. In contrast to coal mining, ore mining requires pre-processing before shipment. In the pre-processing the ore is grinded into smaller stones. This creates one transportation from the mine to the grinder and one transportation from the grinder to a long distance transport. The long distance transport is usually a train or a ship. In a coal mine, on the other hand, the material can be transported directly from the pit to the long distance transport. Though if the distance is long, it might be beneficial to reload the material onto a long haulage truck once out of the mine.
Figure 5: Transportation solutions within the mining industry.
A typical material flow from an open pit mine extracting ore, is shown in Figure 6. The process in an underground mine is in principle the same, with the difference that the first transportations takes place in tunnels. The in-pit or underground transportation takes place between the loading of the blasted material to the unloading at the crusher. A second vehicle transportation moves the material to the long distance transport.
Figure 6: Open pit mine material flow [7].
4.1.2 Safety
The mining industry is among the most dangerous industries in the world [8] and a common problem for all transportation solutions are accidents and deadly accidents in particular [9].
Manual systems are prone to human error and in an analysis of mining incidents, unsafe acts of the operator were associated with 81.9% of the accidents [10]. Manual systems also involve more personnel. An investigation on fatal dump truck accidents shows that truck drivers accounted for 36% of the deaths during 1992-2007 [11]. This indicates that many accidents and deaths can be avoided by introducing autonomous trucks.
4.2 Operating conditions
This project addresses the first transportation in the mine, either over ground or underground, from loading of the blasted material to the pre-processing or reloading of the material. That is not outside the mining area and on no public roads. The transported material may vary from coal to waste and ore.
4.2.1 Environment
As mentioned earlier, dump trucks in the mining industry are working in very harsh environment. The operating conditions are putting trucks to the test and the expected life span of a vehicle is about three and a half to four years [12]. The trucks have to withstand for example rough roads, mud and dust, ice and snow, rocks and stones, temperatures ranging from -50 to 50 degrees Celsius, different humidity and all types of weather [2]. Today most of the mines are located below 2000 meters in altitude with the exception of mines in Peru where they are located at an altitude above 4000 meters [13]. In addition, when operating in an underground mine, blast gases and the risks of cave in after blasts has to be considered.
4.2.2 Terrain
The terrain in mines differ, open-pit mines usually have gradients from 10-16% and underground mines around 14-19%. The road conditions are very different depending on what kind of mine it is. Open-pit mines are ranging from rough, very rough to off-road conditions and are also affected by weather. A road can be washed away or turned into a mud puddle and the terrain can change from one hour to another. Underground mines have more constant road conditions and are not affected by the weather to the same extent. In underground mines, there are many narrow passages and the ceiling can be very low from just under 3 to about 4 meters [14].
4.2.3 Daily operation
The average annual mileage for a mining dump truck is 60 000 – 210 000 kilometres, this mileage is covered in 6 000 – 7 000 hours. During this mileage there are continuous stops for loading, unloading and meeting of other vehicles and personnel in narrow passages. A mining- truck can do up to 200 runs in one day. The speed limit differs depending on country and the mining companies own policies. In India there is a speed limit of 40 km/h, in Brazil 45 km/h and in Indonesia 60 km/h. However, the average laden speed is usually 10-30 km/h within the mine [13].
4.2.4 Customer profitability
To reach a high profitability it is important to understand the vehicle tasks. These can be divided into three main categories; value creating tasks, non-value creating tasks and necessary but non- value creating tasks. As illustrated in Figure 7, a mine hauling truck is value creating when laden and transporting to the unloading station. Two good examples of necessary but non-value creating work are refuelling and driving the truck unladen to the loading point. Examples of non-value creating tasks are queuing, driver breaks and changeover of drivers.
Figure 7: Value creation of mining transportation tasks.
4.3 Benchmarking
4.3.1 Transportation concepts
The identified competition consists of manual or autonomous road and rail vehicles and automatic conveyor systems.
The pre-study [2] states that the autonomous trucks have a good opportunity when either of the loading or unloading point, or both, are mobile. Since conveyors and rail vehicles don’t have the same flexibility as road vehicles, they are mainly a competition when transportation takes place between two fixed points, and are thereby not considered as a big competitor.
Three main road vehicle categories were identified; rigid haul trucks, articulated mining haulers and dump trucks.
Rigid haul trucks
Rigid haul trucks, see Figure 8, has a payload ranging from about 30 tonnes to over 360 tonnes resulting in gross vehicle masses from about 60 tonnes to over 560 tonnes. The load is typically distributed on two axles holding a total of six wheels. They can be as high as 8 meters, with a maximum height of 16 meters while tipping, almost 10 meters wide and over 15 meters long.
Compared to their height, they have a relatively short wheelbase resulting in an outer turning radius of about 20 meters for the largest trucks. The trucks normally have a combustion engine
but can also be equipped with a hybrid powertrain with an electrical motor. There are examples of rigid haul trucks with pantographs that attaches to overhead lines in steep inclinations or over longer stretches [15].
Figure 8: Rigid haul tuck [15].
The rigid haul trucks require broad roads and can have such a high payload that it takes even the larger excavators several batches to fill, resulting in idling time. On the other hand, the high payload allows one single driver to transport large amount of material but this is no longer an advantage when trucks are automated. When the haul truck needs maintenance up to 363 tonnes of payload capacity is standing still. The customer might need many extra tons in payload to be able to operate continuously. With high payloads there are a lot more requirements on the surroundings during both loading and unloading. The loaders have to be bigger in order to minimize the loading time and the ore crushers have to be able to handle a big load. With a wider vehicle the roads have to be a lot wider resulting in either a bigger pit or less depth of the mine. Both of these results in less profits. The vehicles are also very specialized and thereby requires many unique components.
Articulated haulers
The articulated haulers can be divided into two subgroups. Haulers for underground or over- ground use, (a) and (b) respectively in Figure 9. They carry about the same amount of payload from 20 tonnes to 60 tonnes and has similar gross vehicle mass on 40 tonnes to a bit over 100 tonnes and have about the same dimensions. On the over-ground vehicles, the load is typically distributed on three axles holding a total of six wheels. The underground vehicles on the other hand, often have two axels holding four wheels in total. Both the over and underground trucks are about 2 to 3 meters high and 5 to 6 meters high while tipping, where the over ground haulers are slightly higher than the underground haulers. The vehicles overall width spans from about 2.4 to 3.5 meters and the length is typically 9 to 11 meters [15] [16].
Figure 9: Articulated haulers, (a) underground use [16], (b) over-ground use [15].
Characterizing for underground haulers is the low profile, suited for the low roof in the tunnels, with the components placed up to the maximum height of the body. These vehicles outer shape is also optimized for tight corners, often having a chamfered front and rear minimizing both the outer and inner turning radius [15].
The joint just behind the cab and engine allows for rotation around all tree axis and give the trucks a tight outer turning radius of about 7 to 10 meters. The joint makes the vehicle well suited for rough and uneven terrain. The vehicle’s main drawback is that it is very specialized and thereby requires many unique components [15].
Dump trucks
Dump trucks, see Figure 10, are typically basic trucks with a payload ranging from 15 to 70 tonnes and a gross vehicle mass from about 30 to 100 tonnes. A dump truck specified as a heavy-duty truck usually has multiple steering and driving axles to enable maximum load carrying capacity and payload. Trucks for use on public roads are limited by regulated dimensions which may vary between countries. The most common limits to the outer dimension are; width 2.55 meters, height 4 meters and length 12 meters. The unloading of the truck is usually performed by tilting the body over the rear end or sideways.
Figure 10: Scania dump truck [17].
The main advantage of trucks is their diversity and flexibility in both layout and usage. Trucks can relatively easy be built for different tasks, loads and operating conditions while taking advantage of cost reduction through larger volumes and common solutions. However, the diversity of trucks also mean that it never becomes truly specialized. The smaller size of trucks lowers the amount of unavailable load carrying capacity during down-time and allows for narrower benches in open-pit mines. This enables steeper and deeper pits which may result in higher profit by avoiding overburden and allow a bigger fraction of the ore body to be mined within the open-pit. A typical dump truck is also allowed to drive and transport material on public roads which could make reloading unnecessary and transportation more efficient.
Autonomous transport solutions
EU is recognising autonomous trucks as a future transport solution. EU Truck Platooning Challenge 2016 is an initiative from the Netherlands who holds the presidency of the Council of Europe of the European Union. The challenge is a cross boarder project with the truck
manufactures DAF Trucks, Daimler Trucks, Iveco, MAN Truck & Bus, Scania and Volvo Group. The goal is to bring political attention to autonomous driving in Europe and to accelerate the development of smart mobility [18].
DAF and TNO has presented what is called EcoTwin, see Figure 11. A concept where a second truck autonomously follows a first leading truck driven by a driver. DAF’s goal is to have a system on the roads commercially before the year 2020 [19].
Figure 11: EcoTwin platooning [20].
Mercedes are developing a truck for the year 2025, shown in Figure 12, with a high level of automation relieving the driver on highways. The system is called Highway Pilot and manage accelerating, braking and steering. The vehicle supports vehicle-to-vehicle communication allowing it to alert the driver of approaching emergency vehicles. It also notifies the driver on slow vehicles blocking the trucks lane. The system is a type of autopilot. The truck is equipped with rear cameras rather than mirrors and side mounted radars to cover the blind spot. However, Dr. Wolfgang Bernhard at Mercedes concludes that laws and regulations have to change and national lawmakers needs to take action for these vehicles to be able to drive on public roads [21] [22].
Figure 12: Mercedes-Benz 2025 highway pilot concept [23].
Komatsu is offering FrontRunner® Autonomous Haulage System, Figure 13. A system of haulage trucks that can start, navigate along routes, recognize other trucks and vehicles as well as load and unload autonomously. A central computer is keeping track of, controlling and analysing the trucks in real time. These vehicles are able to work long shifts and does not require the same amount of stops as a manually driven truck. The system has been implemented and is tested in mines in Australia [24] [25] [26].
Figure 13: Komatsu autonomous haulage system in Australia [27].
4.3.2 Scania bygglada
A mining truck consists of many subsystems and a selection of components were considered relevant for the vehicle concept. These components include the air tanks, axles, batteries, bodies, brakes, cooling, electrical control units, framework, fuel tanks, pneumatic systems, power take- off units, powertrain, after-treatment and exhaust system, air intake, steering, storage, wheel suspension and wheels.
Air inlet and outlet
The air for the engine combustion is usually taken from the front or closer to the roof via a snorkel. The snorkel is common for heavy duty trucks and is used in order to get cleaner air with less dust. The snorkels can have different length and be fastened to either the cab or the chassis.
The position of the exhaust pipe on the trucks also vary. Its outlet can be placed to the left hand side, right hand side, in the middle of the cassis or vertically behind the cab. A high exhaust pipe requires more space but, besides looking powerful, it keeps the outlet out of water and mud as well as avoiding stirring up dust. If the opening gets blocked the engine has to pump the exhaust against a higher pressure resulting in higher fuel consumption or lower power output.
Swirling dust increases the need of maintenance hence by minimizing dust in the operating environment the maintenance cycle can be extended [14].
Axles
There are many different kinds of wheel setups. The number of wheels on a Scania dump-truck usually varies from 6 to 16 on 3 to 5 axles. Axles can be either steering, driving, both steering and driving or simply supporting. An axle normally holds two or four wheels and can be arranged separately or together as bogies with typically two axles. Wheels can sometimes be raised in order to lower the rolling resistance during unladen operation or to increase traction by increasing the load on the driving axle. Heavy duty trucks normally have rear-wheel drive
or all-wheel drive. They normally steer with one or two axles in the front but may also have steering axles in the rear.
Batteries
Scania offers batteries in two different setups, single and double configuration which both offers several different battery capacities. The single configuration consists of two 12 V batteries in a group giving 24 V and the double configuration consists of two of these groups. The double configuration is used to ensure that at least one group of batteries is charged so that the truck can be started.
Bodies
Scania does not build any bodies, instead Scania’s trucks are built so that different bodies can be fitted. For mining applications, the body typically consists of a flatbed and a subframe. While the flatbed holds the material, the purpose of the subframe is to make sure that the bodywork has the right stiffness and flexibility. The subframe also provides an interface to the truck frame with enough clearance between the flatbed and the wheels and helps distributing the load on to the truck frame.
There are several different unloading techniques and the most common is the possibility to tip the body in one or two directions. Bodies for mining applications on Scania trucks are usually rear or side tipping.
Brakes
Scania uses two main types of brakes, disc and drum brakes, which are powered by a pneumatic system. Drum brakes are robust and enclosed which makes them suitable for harsh environments.
Scania also has two supporting brake systems; an exhaust braking system and the retarder. The exhaust brake is implemented in the exhaust pipe and works by creating a higher exhaust pressure resulting in a higher resistance for the engine. The system is more powerful at low speeds and high engine rpm. The retarder, developed by Scania, is a hydraulic system mounted on the gearbox and generates most braking power in high speed [28].
Cooling
The cooling of the engine is critical to maintain a high efficiency and low emissions. On Scania trucks the cooler is solely positioned in the front. The cooling effect is highly dependent on the size of the cooler which needs to provide the required cooling power. This is usually achieved solely by the head wind but when the speed is too low a fan mounted on the engine behind the cooler helps to increase the airflow.
Electrical control units
Many components on the truck require control by electrical control units, ECUs. There are currently several ECUs mounted on the truck and the number depends on the truck configuration. With an autonomous vehicle it is likely that the number of ECUs will increase, even though some will be removed together with the cab.
Framework
The framework consists of different components, such as side members and crossmembers.
Scania’s side members consist of U-profiles which allows torsion while having a high load carrying capacity. To increase the load carrying capacity a side member reinforcement can be used. The side members are bent to create a Y-shape which enables the engine with mounts and
gearbox to fit. The crossmembers consists of single plate U-profiles which connect the sidemembers.
Fuel tanks
The fuel tanks are made in different material and sizes. Diesel tanks are made out of aluminium or aluminized steel depending on the requirements on robustness, corrosion and weight. Scania has a cylindrical aluminium tank that is specially designed for harsh environments such as rough roads where there are much vibrations [28].
Horn
The horn is used for signalling and is located in the front, lower left corner, of the truck.
Pneumatic system
The pneumatic system is crucial on a Scania truck. It provides power to the brakes and may power trailers, air suspensions and the vehicle body. The system includes a compressor mounted on the engine followed by an air dryer, a pressure regulator and several air pressure tanks.
There are different air pressure tank sizes depending on their positions. The sizes range from 10 litres up to 36.5 litres per air tank. There are some restrictions regarding the placement of the tanks. The tanks must be placed within sufficient range from the brakes to reduce the delay and must hold a sufficient volume and pressure of air. An air suspended chassis must also carry extra volume of air for the air springs. A regular non-air suspended 8x4 has 50-60 litres of compressed air for the front axles and 80-105 litres for the rear axles [29].
Power take-off
The vehicle can be equipped with different power take-off units, PTOs. Engine-driven, flywheel-driven, gearbox-driven and transfer driven power take-off units in case of all wheel drive. When choosing power take-off unit there are many parameters to take into account hence a dialog with the bodybuilder is necessary.
Powertrain
The main components of the powertrain are the engine, clutch, gearbox, propeller shafts, a transfer gearbox in case of driven front axles and optionally a hub reduction gear. Scania’s engines are world leading in performance and emissions. Heavy duty trucks are equipped with diesel engines that may be set up in a hybrid configuration even though there are no examples of that today among Scania’s mining trucks. In the hybrid configuration an electric motor is attached in between the engine and the gearbox, extending total length of the package.
In fully automated Opticruise, providing automatic gearshifts, the clutch is operated by an electric actuator and therefore require no clutch pedal. The gearbox can also be equipped with an oil cooler. This is important if the engine often runs on high engine speed combined with low gear or if the PTO is used often. Automatic gearboxes are not produced by Scania but bought from suppliers. The automatic gearbox is especially good for trucks with many starts and stops.
Hub reduction gears, also known as final planetary gears, provides extra torque which facilitates starting in inclinations and on poor road surfaces easier.
SCR-system
Scania SCR (selective catalytic reduction) is an after-treatment system that minimises the nitrogen oxide (NOx) levels in the exhaust gases. This is done by injecting urea-based additives, AdBlue, into the exhaust gases which converts the nitrogen oxides into water and nitrogen. The injection of AdBlue is done by a nozzle inside the silencer which has many different sizes depending on engine power and emission class. There are also different sizes of the AdBlue tank, ranging from 47 to 124 litres. The AdBlue tank can be positioned on either side of or under the frame.
Steering
Front axles are steered by a draglink arm connected to the steering servo positioned in the front right or left hand corner.
Storage boxes
The storage boxes are frame mounted and used to store tools and components. They come in three sizes; 600 m, 620 mm and 1000 mm in length [30].
Washer tank
The washer tank is located in the front left corner. It is currently being used to clean windscreens and headlights.
Wheel suspension
Depending on the vehicle application different wheel suspensions are used. The main two categories are air and leaf springs which can be used in different combinations. Air springs give good comfort regardless of the load and the possibility to raise and lower the vehicle chassis.
Leaf springs are used when robustness and simplicity is important and the loads are heavy.
Scania has two main types of leaf springs; parabolic and trapezoidal springs. Parabolic springs gives better comfort and has relatively low weight which allows for more payload. They also have a longer life time than trapezoidal springs. Trapezoidal springs can take high loads and does not require dampers but they are heavy and usually used when there are no restrictions on vehicle weight [28].
Wheels
Almost all rims at Scania are tubeless. Rims in steel are more durable but heavier then rims in aluminium and are common in construction and mining vehicles [28]. Depending on the operating environment different tires are used and the most common tire for heavy-duty applications is a larger off-road tire.
4.3.3 Unconventional solutions
There are examples of bodies that enable unloading via hatches underneath the body, pushing the load of the flatbed or unloading it with a rolling belt. These methods do not require the body to be tilted at all and can be effective in tight environments.
There exist many different and some unconventional wheel setups. Bogies can have up to three axles and there are vehicles with up to 20 wheels on up to 5 axels, all-wheel drive and all-wheel steering. There are some examples of vehicles able to steer close to 90 degrees on the front axle and some have separate axles on each side making it possible to steer the wheels individually.
Also some trucks and trailers are tracked rather than having wheels.
There are examples of electrified transportation solutions in mines where hybrid trucks are used.
These trucks can also utilize pantographs for recharging during operation or extending the vehicle electric range. It is then advantageously to position the overhead wires in steeper slopes or long stretches where the road will not be rerouted for a longer period of time.
4.3.4 Scania autonomous trucks
An autonomous mining vehicle must be able to detect other vehicles, pedestrians and objects as well as understanding and judging the terrain. The vehicle also has to be able to communicate with other vehicles and the control centre. To monitor the surroundings, the vehicle utilizes different sensors such as cameras and radars. The sensors complement each other by providing vision of different kinds of objects at different ranges from the trucks as well as giving some redundancy. The sensors require a protected environment, safe from water, rocks, mud and dirt.
One of the biggest concerns, when it comes to blocked vision, is dense particles containing water such as wet snow or slush.
The communication between vehicles and the communication central is performed via antennas.
The antennas must be able to emit and receive signals all around the truck. The signalling antennas also require clearance against metal objects that otherwise would block the signal.
Only minor changes in the chassis layout are mandatory to automate trucks. Sensors, antennas and light for vision and communication are needed to be able to navigate the truck as well as a positioning system to accurately determine the position of the truck. To be able to steer the truck autonomously an electrical steering actuator controlling the steering mechanism is required.
Camera
The camera has a broad field of view and generates a high resolution measurement but its range is limited. The camera has to sit behind a transparent and clean surface in a protected environment. The position of the camera highly influences its measurement. A lower camera can easier identify irregularities in the ground. The camera also benefits from sitting on a rigid part of the vehicle since it is dependent of knowing its exact position. On Scania’s autonomous trucks today, the camera is sitting behind the windscreen in the suspended cab which creates complications.
Radar
Radars are good at detecting hard surfaces reflecting its signal but not as effective on soft objects such as pedestrians. A radar is quite robust and does not require a very clean operating environment. Radars may also be covered by plastic housings without disruption of the signal.
4.3.5 Scania mining truck specifications
Scania mining trucks are usually specified with 3 to 5 axles and four driven wheels. They have a load carrying capacity of 22 to 37 tonnes, loading 9 tonnes on a front axle, 18 tonnes on a rear axle and up to 14 tonnes on a tag axle. The vehicles are equipped with drum brakes, leaf springs and off-road wheels.
4.4 Customer needs
The main function of a transportation vehicle is to hold and move material. In order to do this within a mine many other requirements occur. A full list of these requirements related to the chassis layout can be found in Appendix C.
The vehicle has to be compatible with the loader and unloading stations. It also has to be able to work in different climate and weather, drive on rough terrain, level differences and varying road conditions. To navigate the mine, the vehicle also has to be able to take sharp turns and go around tight corners, see 4.2 Operating conditions. Due to the harsh environment the customer demands robust vehicles with lasting chassis and body [2].
Other important properties are simple, quick, gentle and secure loading and unloading. The truck should minimize operating cost, maintenance and idling time. It should also be able to operate continuously for long hours. The customer wants a flexible vehicle able to fit different bodies and able to transport different material. The safety of the personnel is of high priority within the industry. The truck should therefore lower the risk of accidents, and personnel also has to feel safe around the vehicles [2].
4.5 Legal requirements
Vehicles in the mining industry does not need to follow the regulations of road vehicles since the area in which they operate is considered enclosed. The only regulations that the vehicles need to fulfil are the emission and work-related regulations in each country. Though the customer often demands that the vehicle fulfils the regulations of public roads. It is currently not possible to operate an autonomous vehicle on public roads as there are no laws or regulations allowing that. To enable an autonomous vehicle to operate on public roads it has to fulfil many of the requirements of a normal truck as well as the upcoming laws and regulations regarding autonomous vehicles.
4.6 Market opportunities
Scania’s largest markets are currently located in Brazil, Indonesia, India, Peru, Chile, Russia, South Africa and Australia. Not all of these markets are suited for autonomous mining vehicles, at least not in all parts of the mine. However, there are customers that would buy autonomous trucks if Scania offered these today [14].
The majority of Scania’s sales in mining are for open-pit mining and there are only few examples of Scania trucks running in underground mines, mainly due to low roof clearances. If autonomous vehicles could solve this issue, there would be a new potential market in underground mining for Scania.
The largest potential for trucks is found where the mine is not adapted for rigid haul trucks.
That includes smaller mines, old reopened mines or mines about to open, where trucks can be sold as the transport solution from the start [12]. Scania is for example not selling in-pit trucks in Australia. It wouldn’t be possible to compete against the rigid haul trucks as the infrastructure and loaders are dimensioned for those vehicles. To resize the mine and adapt it to trucks would be too costly for the customer [14].
Autonomous vehicles make the mining process more cost efficient by removing the driver. This does not only save the cost of the salary but the mining company does not need to build infrastructure to the same extent. Today some mining companies have to build hospitals, apartments, airports and stores, as well as providing bus transportation only for their drivers.
Fewer or no drivers would decrease the need of supporting infrastructure.
The removal of the driver will also make more uptime available. There are several occasions where the driver cannot or should not operate. For example, due to toxic blast gases that occurs after a blast. These gases have to be ventilated before a driver can work at that location. Other occasions could be breaks or driver changes. Without the downtime caused by drivers there will be an increase of uptime and productivity.
Another limiting factor for manually driven trucks is the need of driver recruitment and education. It is sometimes hard to find enough drivers when the mine is expanding. In some markets it is common that the drivers lack driving skills. Many of the drivers are not educated truck drivers and they may not even have a license for a regular car. This is especially problematic in India where the circulation of drivers is very high. Scania is therefore unable to keep up with driver education which normally is an important part of Scania’s business idea.
An autonomous truck is programed for efficient driving which lowers wear and saves fuel while minimising risks for accidents. An autonomous truck fleet is also more predictable which enables better management and utilisation of the trucks [31].
5 Product requirements
In order to state a distinct course and establish a strong foundation for the concept generation the product requirements were identified. This was done with a mission statement and a product specification. As a complement and to ensure that the problem is fully thought through, a function degradation was performed. The product functions and components as well as their correlation were identified.
5.1 Mission statement
The course for the concept development is expressed by the mission statement. The mission statement guides the development process and help to ensure that the project is progressing in the right direction. The statement was based on the identified main requirements; autonomous, cab-less, safe, profitable, reliable and transportation of material for the mining industry. The statement says that the project mission is to develop:
“Reliable, cab-less and autonomous vehicles. Designed to improve profitability and safety for transportation of materials within the mining industry.”
5.2 Function degradation
In order to generate chassis layout concepts, it is important to understand what components that has to be considered and how they are related. Therefore, a function degradation was performed to subdivide the vehicle tasks and functions into solutions and required components. The main function to transport material gave rise to eleven subtasks, see Figure 14. Note that, in contrast to manually driven trucks, there is no need of any cab, door, entry, interior or driver interface which allows for many new chassis configurations. The complete function degradation can be found in Appendix B.
Figure 14: Function degradation including eleven different sub-categories.
These subtasks require several components that were divided into three groups according to Table 3. These groups were to be processed during three phases respectively in the concept generation phase. Note that some components might be optional and there may be several
solutions to their task. Group 1 components are associated to the vehicle main attributes such as load carrying capacity, turning radius, length and width. Group 2 components, and the tasks giving rise to them, has a great impact on the chassis layout. Group 3 consists of components with unknown specifications and requirements which thereby requires further investigation.
Table 3: Truck components divided into three categories, phase 1, phase 2 and phase 3.
Group 1
Axles Gearbox
Clutch Suspension
Crossmembers Transfer gearbox
Electric motor Propeller shaft
Engine Wheel brakes
Frame Wheels
Group 2
AdBlue tank Engine protective casing
Air intake Fan
Air tank Fuel tank
Air processing system Horn
Batteries Mudguard
Body Silencer
Bumper Steering system
Cooling system Subframe
Exhaust pipe Washer container
Group 3
Antennas Sensors
Electric computer units Side markings
Head and rear lamps Retro-reflectors
5.3 Product specification
The product specification is an important document that guides projects and establishes a solid foundation for the concept generation phase. The specification was created from the project description and the information acquired during the need finding and benchmarking process. It presents quantified requirements and requests as well as a ranking of their importance. It is also against this specification that the concepts were verified. In Table 4 below a summary of the requirements are shown and the full product specification is found in Appendix C.
Table 4: Summary of product specification.
Requirements and requests Description
Compatible with loaders Requirements influenced by loaders. Such as loading height and load carrying capacity.
Compatible with public roads Legal requirements.
Drivable in environment Defines the accessibility of the vehicle.
Easy to produce Body building and currently available components.
Fit in underground mines Dimensions required by underground mines.
High availability Describes requirements for maintenance.
Human friendly Communication to nearby personnel.
Legal Required laws and regulations have to be fulfilled.
Move material How the vehicle is supposed to function within the mine.
Productive Involves maintaining or improving the productivity. Such as engine power and range.
Robust Requirements to sustain operation in the mining environment.
Safe Safety requirements concerning both vehicle and personnel.
