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% ---------------- Introduction ----------------------
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\section{Motivation and Framework}\label{sc:motivation_framework}

% ----------- Motivation and Framework----------------

	The number of vehicles in operation worldwide is incredibly high and still increasing. In any transportation system, safety is a major issue. This has led to a huge socio-economic effort to reduce driving accidents, which, according to the Eurostat \cite{Eurostat_2013}, is one of the leading causes of death in Europe.

	Safety is also one of the concerns which motivates the \textit{Atlas Project} \cite{ATLAS}. This project was created by the Group of Automation and Robotics of the Department of Mechanical Engineering at the University of Aveiro. The \textit{Atlas Project} is an ongoing work that started with the aim of developing autonomous mobile robots. Nonetheless, it has expanded to the vehicle safety field and has become an endeavour to create a car prototype for research on Advanced Driver's Assistance Systems --- the \textit{AtlasCAR} (Figure \ref{fig:Atlascar}). 
	
	The \textit{AtlasCAR} is a Ford Escort SW automobile equipped with sensors that provide data for the study and research towards new automatic safety systems, and new challenges related to the autonomous driving. Among these sensors there are planar lasers, a 3D laser and a stereo camera that collect data about the surroundings of the car. The \textit{AtlasCAR} also has a GPS receiver that provides positioning, an odometry system that measures the velocity and several computing units responsible for reading all the sensors and controlling the car.

\begin{figure}[!h]
\centering
		\includegraphics[width=0.55\textwidth]{images/atlascar.png}
	\caption[\textit{AtlasCAR.}]{\textit{AtlasCAR \cite{ATLAS}.}}
	\label{fig:Atlascar}
\end{figure}

	Despite the fact that there are many safety systems, presently there is a high interest on computer vision-based techniques such as: analysing eyelid patterns, head movements, facial expressions and even searching for pedestrians or obstacles on the car surroundings. However, most of these techniques require extensive computational processing and high financial cost. As an alternative, other techniques like vehicle-driver interfaces are being considered. These techniques aspire to comply with several requirements such as the following \cite{vigiliance_monitoring}:

\begin{itemize}
\item Low cost of ownership, since an average automobile costumer may not be willing to pay for equipment which significantly increases the final cost; 
\item Real-time and accurate monitoring, to ensure timely detection in detecting possible risk situations and reacting on time;
\item Robustness and independence, meaning that the safety system performance should not be influenced by external factors like traffic, land-scape, weather, and others;
\item Non-invasiveness, a monitoring system that would not distract or impair the driver performance;
\item Easy-to-use and flexible, so it could be user friendly, with a simple and quick installation and compatible with any automobile brand and model.
\end{itemize}

	In order to fulfil all of these criteria, the intelligent monitoring of human actuations in vehicle-driver interfaces represents a great advantage for the assisted driving and for the study and analysis of driving risk situations. Having this as basis, the \textit{Atlas} team proposed a project with the objective to develop a system to monitor human actuation. Because the vehicle pedals are a meaningful source of data output of the driver patterns, these were considered a powerful tool in monitoring driver activity. Hence, this project was entitled "Intelligent Monitoring of Human Actuations on Automobile Vehicle Pedals" and was included in the \textit{Atlas Project}, more properly in the \textit{AtlasCAR}.

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\section{Objectives}\label{sc:objectives}

% ----------- Objectives -----------------------------

	The aim of the "Intelligent Monitoring of Human Actuations on Automobile Vehicle Pedals" is the creation and development of a system able to measure the driver actuation in the vehicle pedals. This system was designed to work in an interactive way, so that the interactions between the pedals and the driver would be measured and simultaneously displayed or stored and in an intelligent way, so that the calibration is smart enough to detect equipment or driving problems. 

	The interactions between the driver and the pedal may be defined by variables such as the force applied by the driver on the pedal and the consequent pedal position shift. The ultimate objective is to correlate these data with other vehicle variables, such as acceleration, engine speed, surroundings of the car, etc. Regarding the vehicle driver monitoring requirements, the system was aimed to be modular, so that it could be easy-to-use, flexible, non-invasive, robust and low cost. 

	The project was subdivided into three main parts:

\begin{itemize}
\item Development of an easy-to-use and non-invasive hardware, to collect data from the pedals; 
\item Design and development of software to monitor and calibrate the system in an interactive way;
\item Evaluation and characterization of the driver's behaviour, through the analysis of the data from the pedals and the other variables of the vehicle.
\end{itemize}

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\section{State of the art}\label{sc:stateart}
\subsection{Transports and Safety}\label{ssc:transports_safety}

% ------------ Transports and Safety -----------------

	In 2011 more than 30,000 people died on the roads of the European Union (EU) and approximately 120,000 people suffered permanently disabling injuries, such as damage to the brain or spinal cord, 240,000 suffered other serious injuries and 1,500,000 minor injuries \cite{EU_Commission}. The number of vehicle accidents is incredibly high and in order to reduce this leading cause of death there is a huge socio-economic effort to improve vehicle safety, safety of infrastructures and driver behaviour. 

	Apart from the basic seat belt and air bag safety systems, there are the Advanced Driver's Assistance Systems, which are intelligent vehicle safety systems collectively referred to as \textit{eSafety} systems. An eSafety system consists of equipping vehicles with electronic devices in order to help a driver avoid danger \cite{EU_Commission}. There are many different types of electronic safety systems for vehicles, and new ones are constantly being developed. They range from collision-avoidance and brake-assistance to lane-departure warning systems. For example by activating the brakes if the car is too close to an object or by emitting warning signals if it strays outside its lane. Intelligent speed adaptation is another example of an advanced system that allows the vehicle to know the speed limit in a specific area and immediately alerts the driver or directly limits the vehicle maximum speed. There are also seat-belt reminders which emit a warning signal alerting the driver that the seat-belt is not fastened. In addition, electronic stability control, a system that reduces loss of vehicle control, can help in critical situations such as bad manoeuvres. To prevent a vehicle from being started if the driver is under the influence of alcohol, vehicles can be equipped with alcohol interlock systems \cite{ISA,seat_belt_reminder,ESC,alcohol_interlock}. 

	Regarding driver behaviour, there are several precautions that could improve road safety, for example: fastening the seat belts, respecting speed limits and not driving under the influence of alcohol or other altered states. Seat belts are the easiest and cheapest way to avoid injury in a car crash. Regarding the speeding, which not only increases the risk of accident but also the likelihood of severe injuries or death, the prevention should consist of a combination of several improvements, from road design to speed limits and driver education. Drivers should not only respect the speed limits but also keep their attention focused on surrounding traffic at all times. Impairment of attention may be due to risk behaviours, such as driving under the influence of alcohol and drugs or to sleepiness, fatigue, monotony and distraction states due to underestimation of physiological needs (Figure \ref{fig:impairing_fact}). Inattention deficits are predominant risk factors in driving and consist of three basic types \cite{
vigiliance_monitoring}: 

\begin{itemize}
\item Visual: factors that distract drivers causing eye deviation from the road, such as checking the mobilephone, GPS, etc;
\item Cognitive: factors that make drivers mentally inattentive or absent, like stress, worries or deep thoughts;
\item Manual: factors that cause drivers to take their hands off the steering wheel, for example, picking something that fell on the floor, smoking, etc. 
\end{itemize}

	Even though there are vehicle- and infrastructure-safety systems available aimed to diminish the severity of accident consequences, nowadays, the desired solution is to have a system that works by detecting high risk of accident and preventing accidents, instead of diminishing their consequences \cite{EU_Commission}. Monitoring driver performance has been seen as a crucial method to prevent accidents.

\begin{figure}[htbp]
\centering
		\includegraphics[width=\textwidth]{images/alertnessscheme.pdf}
			\caption[Factors that affect driver performance.]{Factors that affect driver performance \cite{vigiliance_monitoring}.}
				\label{fig:impairing_fact}

\end{figure}

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\subsection{Monitoring Human Performance}\label{ssc:monitoring_performance}

% ----------- Monitoring Human and Vehicle Performance -----------

	Some driver behaviours that impair safe driving can already be detected in real-time. For instance, drowsiness and inattention can be captured through image acquisition and processing of facial features such as eye and head movements \cite{vigiliance_monitoring}. However, these image processing techniques are associated with high computational costs and only capture the head or upper body. 

	As an alternative there are other Advanced Driver's Assistance Systems that not only can monitor the physiological responses of the body while driving but also have the advantage of interacting with the driver --- vehicle-driver interfaces. Vehicle-driver interfaces based-systems have the potential to improve safety by observing and interacting with the driver, leading to a decrease in risky behaviours and consequently road accidents \cite{behaviour_prediction}.

	Vehicle-driver interfaces include the accelerator, brake and clutch pedals, the steering wheel and the seat \cite{vigiliance_monitoring}. There are some techniques for vigilance monitoring based on these vehicle-driver interfaces, like steering wheel and seat pressure monitoring combined with actuation on the pedals. For instance, measuring forces using force sensitive resistors (FSR) on pedals, together with monitoring of the steering wheel improves the detection of driver's alertness state \cite{vigiliance_monitoring}. In addition, using a driving simulator (Figure \ref{fig:driving_simulator}), the behaviour signals measured on the steering wheel and on the pedals provide the possibility to determine the driver's identity \cite{behaviour_signals}. If the pedal data is combined with seat pressure data, monitoring the pedals also improves the analysis of driver ergonomics \cite{ergonomics}. Moreover, by monitoring the engine moment, the acceleration and the steering wheel together with the brake pedal data, it is possible to analyse the driver's condition and capabilities \cite{driver_condition}. Finally, a system combining the data from the pedal position with the vehicle location, speed, acceleration, fuel consumption and the heart rate of the driver can assist in the characterization of driver behaviour as well as in the identification and mapping of potentially dangerous locations \cite{behaviour_road_identification}.

	The availability of vigilance monitoring systems using only output from the pedals is far more restricted. A project where data from FSR on pedals was used to identify the driver by analysing driving performance patterns, based on previously collected data, is one of the few examples \cite{andre_oliveira}. 

	A driver performance monitoring system should be low cost, non-invasive, easy-to-use, flexible, and real-time accurate \cite{vigiliance_monitoring}. However, the few commercially available systems for monitoring the pedals usually lack modularity and flexibility. A very flexible and easy-to-use system to monitor the pedals, which could be easily installed and readily used in any vehicle or machinery would therefore be of great importance, filling a major gap in the field. Moreover, if capable of combining both the ability to measure applied forces on the pedals and the consequent shift in distance between the pedal and the floor of the car, this system would represent an even more accurate and robust method than the presently available.

\begin{figure}[htbp]
\centering
		\includegraphics[width=0.5\textwidth]{images/driver_simulator_DRIVER_IDENTIFICATION.png}
			\caption[Driving simulator to collect behaviour signals.]{Driving simulator to collect behaviour signals \cite{behaviour_signals}.}
				\label{fig:driving_simulator}
\end{figure}

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\subsection{Intelligent Monitoring}

% --------------- Intelligent Monitoring -------------

	With an intelligent driver performance monitoring system, it could be possible to collect and analyse several aspects of the vehicle continuously, while driving. By analysing and recording the braking situations, braking patterns could be defined overtime. With this it would be possible to infer from a braking situation, if the system would require more or less force to be applied on the brake pedal to brake safely, and the driver could be warned accordingly. This braking assistance could lead not only to a more safely braking but also to a more efficiency braking situations. Because of the continuous degradation of the braking system and other external factors, such as road slopes, weather, etc, braking patterns change continuously. Thus, re-defining them along the driving so that the driver could always have an assisted braking would very likely increase the efficiency of the braking system of the vehicle.
	

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