PRE2016 3 Groep11

Introduction

With the expectations of the current car development as well as the current state of the art, it’s highly likely that autonomous cars will cooperate in traffic. The development steps, innovativity and the inventivity of big companies which support the production of autonomous cars, such as Tesla, BMW and Google, are - with an increasing rate of confidence - stating that it will be a matter of years before the first great share of autonomous vehicles on roads will be noticeable.

This will logically result in a mixture of both non-autonomous as well as self-driving vehicles. Autonomous vehicles have abilities with respect to reaction time and affiliation that are way advanced in comparison to human drivers. This will most likely be a cause of some interference between both of the vehicles with respect to the current traffic system. The differences that both vehicles have in reaction and processing time can be unbeneficial for places where there is an almost continuous amount of much traffic.

This will especially occur in the rings of big cities, where the amount of traffic is big and chaotic most of the time. It is at this place in a city, where almost all other roads of the city can be reached. So these rings will be packed with traffic that has destinations in the city center, but also traffic from the city center that wants to reach out of the city bounds.

This report will be focusing on the development of a new system for traffic lights, so autonomous and non-autonomous vehicles will show more cooperation as well as an improved fluency. This project will look into the effects of a new traffic system that can be utilised on rings in the center of big cities. The density of traffic, the average speed, the passing time and CO2-emission are results that are aimed to look after in this report.

Authors

• 0960493 Tim Houthuijs
• 0934016 Kevin Jenniskens
• 0958509 Matthijs van Raaij
• 0948190 Sarah Rohder
• 0903327 Floris Tulner
• 0945501 Lars Verstraelen

2 Focus, Objectives and Approach

2.1 Focus

We have set up a few questions and subquestions in order to guide us through the process of coming up with a result for this issue. The main question we want to answer is: With how many non-autonomous cars will platooning through a green wave still be efficient?

To answer this particular question, we have divided it up into different subquestions which will ultimately let us form a final answer to our main one. These include the following:

- What exactly is platooning?

- How many cars are there in a green wave?

- How does platooning work at 0% until 100% non-autonomous cars?

- How do different vehicles function in platooning?

- What is the minimal velocity a vehicle or platoon has to be at to not be a danger on the road?

Requirements

• 2 lane road, with near traffic lights left and right turn lanes
• all ((autonomous?)no annoyed/annoying drivers?) vehicles will stay below speed limitations
• sensors in road between traffic lights to sense cars
• traffic intensity for enter / exit roads can be adjusted
• communication between autonomous cars as well as traffic lights can contain:
  • traffic systems can send recommended speed to autonomous cars
  • speed and location of the cars can be send
  • acknowledgement data received
  • perhaps sensor data of the length of a platoon can be send
• traffic lights have a max time to be on green so a platoon has also a max length

Constraints

• emergency vehicles will not be simulated
• platoon = 7+ cars (may be subject to change)

Assumptions

• communication between traffic lights and autonomous vehicles have unlimited range
• all cars have same fuel usage/efficiency if co2 is considered
• all cars follow shortest distance to destination
• pedestrians and bicyclists follow the rules and only pass when they are allowed to
• human driven cars don't pass a red light

2.2 Objectives

• Find current algorithm that can make platooning in these circumstances
• Create a new algorithm for platooning in a ringlike traffic situation
• Adjusting the algorithm to make it optimize its use of green waves
• Try to realistically base it on “de ring van eindhoven”

3 USE aspects

The situation that is developed in this Wiki is reminiscent of a situation that can be found in real life. Obviously, it is a simplified model of such a real life situation, but suitable for this project. However, even if the model is simplified, the different aspects of the real life equivalent should not be ignored. For instance, the role of the pedestrians that can be found trying to cross the ring are practically reduced to the assumption that that only happens when the light is red for the automobiles. However, to just ignore a such significant user of the traffic system in the Netherlands is quite brash. Thus, in this section the different USE aspects that are important to the specific simplified model of this project will be discussed, but also those in a similar real life situation, where the stakeholders should be the same.

Users

The users of the traffic system in the Netherlands consist of everyone participating in traffic. This ranges from users on wheels, such as automobiles and lorries, to pedestrians and cyclists. Even within these user groups there are different preferences and wishes to how the traffic system should look like. For instance, automobilists want to drive as fast as possible, while never having to stop for something else. Pedestrians want to safely walk alongside the faster traffic, such on curbs, and be able to cross the road where they need to. Obviously, this contradicts each other in a way. So, an overview of these different groups need to be made, such as can seen in (BELOW).

Automobilists (cars, lorries)

• Want to drive as fast as possible
• Nothing that slows down or stops their journey (such as traffic lights)
• If there is a waiting time, let it be as short as possible
• Good quality roads
• Everybody keeps to the traffic rules

Pedestrians

• Safe place to walk
• Safe place to cross the road
• If there is a waiting time, let it be as short as possible
• Everybody keeps to the traffic rules

Cyclists

• Safe place to cycle
• Wants to cycle as fast as it can
• Nothing to slow down or stop their journey
• If there is a waiting time, let it be as short as possible
• Good quality roads
• Everybody keeps to the traffic rules

Special types of vehicles (ambulances, fire trucks)

• Being able to pass regular traffic in an emergency in a safe way
• Travelling time as short as possible
• Always green lights for any traffic light

Unfortunately, not all of these wishes can be granted, nor can all wishes be considered in this projects simplified model. For instance, a constraint of the model is that special vehicles, pedestrians, and cyclist will not be modeled into the system. Pedestrians and cyclist will be present, they will just not be separately simulated, as the assumption is that when the light is red for the ring users, then those two groups can safely cross the ring. Furthermore, since the simulation is based around optimising a traffic light-based system, it is difficult to grant the wish to all users that they never have to stop during their journey. However, the goal of this project is to try to optimise the waiting time, making it as short as possible for all present users. Additionally, this should also create a safer traffic environment for all involved, granting at least a few of the wishes of every user.

Society

The next important stakeholder in the ring-based traffic system is Society itself. Society also consists of the previous mentioned users, but also users that do not participate (at the moment) in the traffic system, thus keeping their wishes in mind as well. Furthermore, Society also has different interests and smaller stakeholders within, such as the environment, the economy, and ranking compared to other Societies (such as in a different country). An overview of the wishes in the Society needs be made, but it also needs to be clear what kind of different groups are represented in this projects Society,

Environment

• The CO2 emission should be lowered
• There should be less pollution
• No destroying the environment
• Society needs to be green, and look/see green (think planting trees and such)

Economy

• The quality of the traffic system should be at a minimum level, preferably higher
• Any change to the traffic system should be as cheap as possible
• Everybody needs to be able to reach their destination as fast as possible, since any delay costs *money

Compared to other Societies

• This Society needs to be the greenest
• It needs to have the safest roads
• It needs to have the highest quality of roads

Other User groups

• The roads need to be as safe as possible
• The roads need to be clean (think, no garbage from cars and such)
• The traffic should preferably be as far away from Society as possible

Enterprise

At the enterprise side, we have got the actors of the producers of the autonomous cars (think of for example Tesla or Google), and software companies that develop traffic systems (examples to be looked up).

These actors also provide certain pros and cons. These include more jobs in the autonomous car industry, large sales for autonomous car producers and lots of jobs in the informational sector. This last one may have an issue as there might not be enough people in this sector.

5 Traffic systems

5.1 Contemporary traffic system

Currently a very standard model is being used fort he structuring of traffic. 90% of the traffic lights (in big cities as well as small villages) work as follows: when a car approaches a traffic light, it is either green or red. When it turned red, the traffic light waits for the traffic lights in the area to either turn red or to accommodate to a situation in which both this traffic light as well as the others can work. Then it will turn green with an initial green time. When no more traffic is passing through, the light will turn to red in less time than the green time was supposed to last. If traffic is passing continuously, then the green light will turn red after the green time has passed.

5.2 Traffic system by previous group

(Voor Matthijs Nieuw t.o.v. 26-3): Group PRE2016 1 is a collection of students who were already working on creating on a new traffic system at intersections. This group didn’t necessarily concentrate on a system where lights are turned green or red when a car is waiting in front of it. They instead made a system in which the greentime and the moments when a light is turned green, is dependent off of the amount of cars that are waiting in front of the traffic light. To turn this system into a practise, a cost function was defined which determined whether a light has a priority on other lights to turn green. This function is defined as follows: C(t,N,B) = N + B + c_1 * t + P_1 * e_1(t)

Here are:

C(t,N,B): The total cost dependent off of the amount of both non-autonomous vehicles and vehicles with human drivers as well as the waiting time

[math]\displaystyle{ N }[/math]: The amount of autonomous vehicles

[math]\displaystyle{ B }[/math]: The amount of non-autonomous vehicles

c_1: The constant to provide the severity of the waiting time in front of a traffic light

t: The waiting time

P_1: A large value (in the order of thousands)

e_1(t): A function switching to 0 if t<30 and to 1 if t>30

So the bottom line of this function is: a green light is provided to the biggest row of cars in combination with their waiting time. This function is implemented in each traffic light at the intersection.

5.3 City ring traffic system

The system that we are looking into, is mainly targeted to be used on rings of big cities. To describe this idea, an analogy with a clock is being proposed: a clock has a cursor which turns around its own axis. This pointer slides along the circumference of the clock. One can imagine the end of this cursor to be a car, which passes over a road with a constant speed. This is what we assume of a green wave: a state in which cars are allowed to pass sequent green traffic lights by traveling at a constant speed (within a degree of error in reality). This means that the traffic system can easily be corresponded with the speed of the car. The only thing for this system that we need to know, is what the speed limit should be of the road it’s traveling on. For instance when the speed limit is 60 km/h, and one has just past a green traffic light, and the next one is appearing in about 1 kilometer, then the next traffic light should turn green one minute after the previous one has turned green. This time is set that way because within this time, assuming a car will drive with a speed equal to the speed limit, then it will cover that one kilometer in one minute as well. This way, when the car is driving at a constant speed, it can always pass a green light. This is all because the moment the next light turns green, is slightly earlier (due to accelerating from 0 to the speed limit) then the moment where the car arrives at the traffic light. This way the car can drive further without pressing the brakes to slow down. This now introduced traffic system, will be crossed with the traffic system made by the previous groups. So on one hand, at the intersections the main focus is to give advantage to the longest row of vehicles. This whilst a green wave is being forced through the ring, so this green wave has a priority on the intersectionsystems when it is about to pass through an intersection. This means that an alternate cost function needs to implement green waves as well. The new cost function for our system is:

C(t,A) = A^T(t) + c_1 * t + p_1 * e_1

Here are:

C(t,A): The total cost dependent off of the amount of cars in a row and the waiting time of the car who has to wait the longest at the intersection to cross it.

A: The total amount of cars in an intersection row

T(t): A function that shows whether a row is in a green wave, and where

c_1: The constant to provide the severity of the waiting time in front of a traffic light

t: The waiting time

p_1: A large value (in the order of thousands)

e_1(t): A function switching to 0 if t<30 and to 1 if t>30

In this function it is implemented that a light is turned green earlier when a row at an intersection is in a green wave.

New Cost Function

As stated and defined above, a new cost function is presented to create the traffic algortihm. As one can see, there are a few differences. First of all N + B is being replaced with just a regular capital A, which stands for the total amount of cars (assuming that these are all man-driven). The rest of the constants that were already in the cost function made by group PRE2016 1 are still in the formula. A major difference however is the function T(t). This function provides to which the total amount of cars in a row at an intersection is put. Note that this function is always greater or equal to 1. This function behaves like a tent when the row is in a green wave (generated as a traveling signal through the total traffic system). When the green wave begin with its passing by the value starts to rise. It reaches its peak at the middel of the green wave signal (the green wave signal and the system is explained in the part aout thew simulation). After the middle of the signal has passed, the values of the function start to linearily drop to 1. So now, when a green wave passes by, it has to seem, to the traffic light, that there are a lot of cars waiting to cross the street. This will have the traffic system which throughputs the green wave, give a priority on crossing in relativation to the the rows which have a relatively fewer amount of cars waiting. After all, the traffic light with the highest cost of all of the lights in the intersection, turns green first (as created by the past group). Depending on how big the value of c_1 is, the waiting time of the cars will also be weighed in the cost function. When this value is made larger, priority is given to the row which has the cars that are waiting the longest. So the weight will proportionally grow with the implementation of waiting time. p_1 is a large value (like 10000) which will only be put into the cost function, when the longest waiting car in the row had waited for 30 seconds or longer. This is obviously implemented to prevent one car from waiting to long, when a large amount of cars are on the other roads.

6 Simulation

A representation of a traffic system

To simulate the traffic situation a square road plan which will symbolize the “ring of Eindhoven” with a reduced amount of intersections will be simulated. There will be 24 intersections in the simulation to test how platooning will work over several intersections. For the traffic light system a new algorithm was imagined where all traffic lights in the ring are connected in a spinning wheel type. Imagine the hour slots on this clock to signify the intersections on the outer ring of the clock. The new algorithm would connect every 2 opposing intersections in figure [fignummer] to one state. This control system is used to make the simulation more responsive to platoons, as well as make the control of the intersections a bit easier. The state of the intersections depend on what the sensors between the previous and the one before that say, as well as the sensor before that. So for example the 12 and 6 o'clock positions are dependent on the sensors between 1-2 and 2-3. If a platoon is on its way it will try to make it possible for the platoon to be in the green wave.

figure [fignummer] A representation of a traffic system

A simulation was made in netlogo to figure out how different percentages of autonomous vehicles versus non autonomous vehicles would affect platooning. As outputs on the simulation a few values are important;

• Number of vehicles stopped in the simulation
• average time stopped(of vehicles going forward )
• average distance driven,
• average speed of cars
• average number of vehicles on the road.