1 of 8
2 of 8
Figures 2a-c: Google driverless cars.
3 of 8
Figures 2a-c: Google driverless cars.
4 of 8
Figures 2a-c: Google driverless cars.
5 of 8
Figure 3: Passengers relax with electronics in this driverless concept mockup from Rinspeed. Credit: © 2014 Rinspeed
6 of 8
Figure 4: Hydrogen Fuelled Car.
7 of 8
Figure 5: Toyota Concept Hydrogen Car.
8 of 8
Figure 6: Example of a hydrogen storage tank located in rear of a car.
David Tolfree, VP MANCEF
Developments in micro technologies in this century have enabled the production of a wide range of smart sensor systems. They are the brains of all autonomous vehicles. Advances in microchip design and miniaturisation integrating increased sensitivity and functionality with intelligence, result in smart sensors being the building blocks of all automated systems.
One of the critical elements required to support autonomous decision-making is the fast collection and analysis of data to provide a real-time digital picture of the environment within which vehicles operate. An autonomous vehicle has to be capable of interpreting this sensory data fast, reacting to it and navigating without human input.
Surroundings and objects can be detected using a variety of techniques, the most successful being LiDAR (Light Detection And Ranging). Combined with other optical and thermal camera sensors, a vehicle can build a visual picture of its surroundings close to that which could be obtained by a human.
Aircraft with autopilots and driverless trains have been operating reliably for many years. Pilotless aircraft (drones), although normally controlled remotely, can be totally autonomous. Many metro train systems operate autonomously. Unlike automobiles these operate in a controlled space and run on fixed tracks. A physical barrier therefore exists between them and people. Cars can be driven independently on roads with minimal restraints. This places challenges on the designers and manufacturers of driverless cars.
Recently, while driving home along a busy country road thinking about writing this article, I had to brake for an overtaking car, observe some road signs, and be aware of pedestrians walking on the payment. My brain had to almost simultaneously analyse these along with other distractions and transmit signals to my arms and legs so that I could control the car. It made me appreciate the challenges that confront designers of driverless cars. Our brain neurons act like individual switches but collectively add to produce analogue signals to send to various parts of the body to act. It is this analogue operating system that differentiates us from machines that operate digitally.
Intelligent humans can sense, analyse, interpret and extract information stored in their brains from past experiences using a parallel processing system. Sometimes flaws in this cause misinterpretations but at the present time the brain has superior storage and processing power over any computer. This could change in the future.
The Google Car
For a number of years prototype driverless vehicles have been undergoing tests in the US, Japan and elsewhere. Six US states have licensed driverless cars allowing their use under controlled conditions. One of the most publicised US projects is the Google Car (1) that uses the LiDAR to sense the surrounding environment. A Velodyne 64-beam laser system fitted to the car, accurate up to 100 feet, can rotate 360 degrees and take 1.3 million readings per second to produce a detailed 3D map of the car’s environment. Radar and sonar systems mounted on its front and back bumpers can signal any imminent impact and constantly regulates the car’s throttle and brakes.
Google's fleet of robotic Toyota Priuses has now logged more than 190,000 miles driving in city traffic, busy highways, and mountainous roads with only occasional human intervention. These tests demonstrate a significant step towards solving the many problems that still confront designers of driverless cars.
Other companies, including Volkswagen, Mercedes-Benz, BMW, Tesla, Ford, Nissan and Honda are testing autonomous cars. A race is on for who can produce the most reliable, safe and cost-effective vehicle.
Most of the technological problems of autonomous functionality are soluble but the greatest hurdles will be public acceptance and issues related to liability, regulation, cost and legislation. But perhaps the love of hands-on driving will, for most, be the greatest resistance to the acceptance of this form of transport. Young people in particular love driving so they, together with professional drivers, will provide the most opposition. The ageing population is much more likely to welcome driverless cars.
Power Sources
The other problem that must be solved before autonomous vehicles are universally adopted is the power source. Vehicles will be electrically powered so improved battery systems will need to be developed to overcome the current range limitations they impose. Electric cars are becoming increasingly popular so manufacturers are giving high priority to developing more powerful batteries. Tesla, Bosch and other companies are actively working on improved lithium ion batteries. Initially it is likely that autonomous cars will be owned by fleet operators and leased or hired. This will reduce the need for individual car ownership. Hence the dependence of long-range electric cars will be reduced since journeys can be made with more than one car. Already in some areas autonomous vehicles are used to ferry passengers short distances from city centres to train stations and airports.
It is likely that traditional chemical batteries will eventually be superseded by hydrogen fuel cells. They were originally developed by NASA for space vehicles. The demand for zero pollution emissions is now increasing the interest by many leading manufacturers in hydrogen fuel cell development.
Hydrogen cars are basically cars with electric motors driven by electricity generated by a reverse electrolysis process in a fuel cell stack. The electricity generated by the fuel cell stack powers the electric motor that propels the vehicle. Each fuel cell has an anode, a cathode and a proton exchange membrane sandwiched in between. Hydrogen, from a pressurised tank in the vehicle, enters into the anode side of the fuel cell. Oxygen, pulled from the air, enters the cathode side. As the hydrogen molecule encounters the membrane, a catalyst forces it to split into an electron and a proton. The electron follows an external circuit, delivering current to the electric motor and other vehicle components. At the cathode side, the proton and electron join again, and then combine with oxygen to form the vehicle’s emission, water. Increased efficiency of the process can be obtained by using nanostructured materials as catalysts.
Hydrogen has the highest energy content per unit weight of any known fuel but it does not occur naturally without attachment to other elements like oxygen or carbon so is costly to separate and transfer into fuel cells. Natural gas provides 90% of the hydrogen made in the world today. Hydrogen gas has to be stored under pressure to meet the necessary volume requirements to provide an effective fuel cell for a car. One gram of hydrogen (H2) occupies approximately 12 litres of volume at room temperature and atmospheric pressure and will drive a car only 100 metres. To meet the needs of a car at least 50,000 litres would be required so the only practical way is to store the gas under pressure. Cars therefore need to have strong pressure vessels as fuel tanks. Refueling takes as little time as using petrol and therefore has the advantages over the long charging time required for batteries. The cost, however, of extracting hydrogen gas from its compounds is high at present but the possibility of using electricity provided by renewable sources such as solar and wind for the extraction process could reduce this considerably. Water as fuel source is abundant on the Earth.
As an anecdote, in his1894 book, ‘The Mysterious Island’ Jules Verne wrote:
I believe that one day water will be used as a fuel. Hydrogen and oxygen which constitute it will separately provide an inexhaustible source of heat and light of an intensity unknown to petroleum. One day instead of being fired by coal, steamships and trains will be propelled by these two compressed gases which will burn their engines with enormous energy. Water is the coal of the future.
Markets
A Boston Consulting Group predicts a $42 Billion market for autonomous cars by 2025. According to Navigant Research (2), 85 million autonomous-capable vehicles are expected to be sold annually around the world by 2035. Such estimates could be very wrong since many technical and economic developments could take place before these times that could change expectations.
Looking to the Future
There is little doubt that autonomous vehicle technology will produce a paradigm shift in transport systems, particularly in large cities. The long term effects of autonomous vehicles on society could be far reaching.
Looking ahead, semi-autonomous, then fully autonomous vehicles will be phased in and driven on the roads along with traditional vehicles. Eventually, and sooner than perhaps we realise, all new automobiles will be able to drive themselves, changing our lives almost as dramatically as the earliest cars impacted the lives of our ancestors. But all countries will have to establish integrated transport systems involving air, sea and land to avoid bottlenecks if people and goods are to move without delays across the world. As the demand for travel increases exponentially in the coming years, the current situation on the roads and at airports will become unsustainable. The promise held out by autonomous vehicles is that road pollution, accidents and congestion could be reduced. But like so many other technological advances that race ahead of investment in infrastructure development, these may take much longer to achieve than predicted. But whatever difficulties and obstacles arise, the direction for future transport is already set.
References
1. https://www.google.com/selfdrivingcar
2. https://www.navigantresearch.com
David Tolfree is currently the MANCEF Vice President. He is a professional physicist with 40 years’ research and managerial experience working for the UK’s Atomic Energy Authority and Research Councils. He was the co-founder and director of Technopreneur Ltd, a technical consultancy company for the commercial exploitation of micro/nanotechnologies and a consultant to UK Government departments on micro/nanotechnologies. He is one of the founding members of MANCEF and the UK Institute of Nanotechnology and is now a member of the UK KTN. David has written 162 publications, including roadmaps, newspaper, conference, magazine and journal articles and books. He has given interviews on television and radio on micro/nanotechnologies, and has been an editor and reviewer for a number of related scientific journals. He currently serves on the editorial Advisory Board of the International Commercial Micro Manufacturing Magazine.