Journal of Robotics, Networking and Artificial Life
Vol. 5(4); March (2019), pp. 261–264
DOI: https://doi.org/10.2991/jrnal.k.190220.012; ISSN 2405-9021 print; 2352-6386 online
https://www.atlantis-press.com/journals/jrnal

Research Article

Control System for Maintaining Safe Following Distance
while Driving
Kuo-Hsien Hsia1,*, Jia-Hong Cai1, Shu-Li Pai2, Evgeni Magid3
Department of Electrical Engineering, Far East University, Xinshi Dist., Tainan 74448, Taiwan (R.O.C.)
Global Learning and Assessment Development, Greater China, Chaoyang, Beijing 100020, China
3
Laboratory of Intelligent Robotic Systems (LIRS), Intelligent Robotics Department, Higher Institute for Information Technology
and Intelligent Systems, Kazan Federal University, Russia
12ARTICLE INFO
Article History
Received 3 September 2018
Accepted 20 October 2018
Keywords
Driving safety
safe distancedriving speed
weather conditions

ABSTRACT
Safety is the most important issue while driving. Many traffic accidents occur because of insufficient safe distance. With theadvancement of technology, there are cars with a front distance safety warning system. Some of them are with fixed safe distanceregardless of the speed of the car. Other advanced distance detection systems switch between different modes such as highspeed and low speed. In this paper, we proposed a driving safety system which can dynamically adjust the safe distance between
vehicles depending on the speed and weather conditions. This system can be used to determine and maintain safe distances bothin front and rear of a car. This idea has obtained an invention patent of Taiwan. A car with this system can be driven more safely.
© 2019 The Authors. Published by Atlantis Press SARL.
This is an open access article distributed under the CC BY-NC 4.0 license (http://creativecommons.org/licenses/by-nc/4.0/).

1. INTRODUCTION
Living in this era, transportation is inseparable from people’s
daily lives. Many people often drive to work or travel. For somepeople, driving is their work. So, driving safety is an absolutely
important part for them. According to the annual report of theFreeway Bureau, Ministry of Transportation and Communications(MOTC), Taiwan, the reasons for the top ten accidents on the superhighway of Taiwan in 2015 are as follows [1]:(i) Not maintaining the driving safety distance (50.5%).
(ii) Not appropriately changing lanes or directions (12.8%).
(iii)	Not paying attention to the state in front of the car (10.3%).
(iv) Other violations that caused accidents (8.0%).
(v)	Backing the car without accordance with regulations (2.2%).
(vi) Wheel shedding or tire burst (1.8%).
(vii) Loading goods not safely fixed (1.3%).
(viii) Drunk driving (1.1%).
(ix) Vehicle parts falling (0.7%).
(x) Not maintaining driving safety interval (0.6%).
Traffic accident analysis reports in many countries have similar
conclusions. Statistics of traffic accidents show one of the mostcommon causes of traffic accidents to be the “failure to observea safe distance behind another vehicle [2].” There are three safe
distance required in car-following [3]: front safe distance, rear safe
distance, and lateral safe distance, as shown in Figure 1. Everybody
Corresponding author. Email: khhsia@mail.feu.edu.tw*

knows that keep safe distance in driving is very important.
Considering the three safe distances, the front distance can almost
completely controlled by the driver. Studies have shown that leaving more space between vehicles helps to reduce traffic accidents
and allows for smoother traffic [4].
There are many factors that may have influence on safe distance.
For example, speed of the vehicle, driver’s attentiveness, size andcondition of the vehicle, road surface, and weather conditions are
all factors of the driving safety distance. An article of World HealthOrganization (WHO) shows that speed has been identified as a key
risk factor in road traffic injuries, influencing both the risk of aroad crash as well as the severity of the injuries that result fromcrashes [5]. A good suggestion for keeping safe driving distanceis “two-second rule.” The rule is that a driver should ideally stayat least 2 s behind any vehicle that is directly in front of his or hervehicle [6]. However, counting seconds may cause distracting forthe driver. Another guiding rule about safe distance (in meters (m))
on the super highway in Taiwan is half of the speed (in km/h) forsmall cars and speed −20 for large cars.
With the advancement of technology, there are cars with a front
distance safety warning system. Some of them are with fixed safe
distance regardless of the speed of the car. Other advanced distancedetection systems switch between different modes such as highspeed and low speed. However, from earlier discussions we knowthat the safe following distance closely regards to the speed of thevehicle. In this paper, we will propose a driving safety system which
can dynamically adjust the safe distance between vehicles depending on the speed and weather conditions.

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3. EXPERIMENTAL SIMULATION

Figure 1 | Distances that should be concerned by the driver.

2. SYSTEM ARCHITECTURE
Our system is primarily designed to alert drivers when there isinsufficient safe distance from the vehicle in front. The systemarchitecture is shown in Figure 2. We modified the rule of safe
distance promulgated by the Freeway Bureau, MOTC, Taiwan byconsidering the environment parameters such as uphill/downhill,
heavy rain, and thick fog. Hence the driving safety distance can be
adjusted dynamically. The function of the safety distance in front of
the car is shown as Equation (1).
d = f (v , r , g , s)ìvï * (1 + r + g + s)
for small car= í2
ïî(v - 20) * (1 + r + g + s) for larggecar
where 0 £ r , g , s £ 1.

To promote our patent concept, we constructed a simple simulation
experiment system. An HT66F50 is used as the central processing
unit of the system. An ultrasonic sensor is used as the front distancedetector. We use a sliding-type variable resistor to simulate thethrottle acceleration system. To detect that the car is on an uphill/
downhill state, we use two mercury switches configured as inverted
V-type, as shown in Figure 3, to detect the attitude of the car. If thefront switch is closed and the rear one is open, then the car is on adownhill slope. If both switches are closed, then the car is on a horizontal road. However, due to the acceleration will affect the actionof the mercury switch, the mercury switch is not suitable for use
on actual cars to detect uphill/downhill. An alternative way for theuphill/downhill detection is to use the relationship between throttle
and speed changes. Our experimental car for simulation is shownin Figure 4. All circuits are packed into the cabin of a model car.
An LCD (liquid-crystal display) for display the message of simulation result is mounted on the roof of the model car. Figure 5 showsthat the car speed is at 95 km/h. No rain and no fog is detected atthat time. By Equation (1), we know that the safe distance shouldbe 47 m if the car is on a horizontal road. But from the display
panel, we know that the car is in a downhill state. Hence the safety
distance should be larger than 47 m. Figure 5 shows that the safety
distance should be 70 m and the detected front distance is 39 m,
and hence the alarm system will be activated.

(1)

Here d is the safe distance, v is the speed of the car, r is the statusof rain, g is the status of fog, and s is the slope of uphill/downhill.
The parameter r is 0 when it is not a rainy day, and is 1 when it isheavy rain. The parameters of g and s are defined in similar way.
For example, a small car is driven on the highway at a speed of
110 km/h, with clear weather and non-uphill/downhill sections,the safety distance should be 55 m. For the same speed but in thedownhill section, the safety distance should be more than 55 m.
This system can be integrated into the driving computer to form
a complete driving safety system, or it can be an independentlyoperated driving safety assistant system. For the integrated system,
the system can remind the driver to slow down or automatically
activate the brake system to force the deceleration when the safety
distance is insufficient. For an independently operated system, thesystem can only alert the driver to slow down without any mandatory action.
The alarm unit can include an audio alert and a light alert. The
sound or light warning in the car can remind the driver to properly
slow down to avoid the danger of chasing. If there is a light warningat the rear of the vehicle, it can alert the driver of the rear car thatthe safety distance to the front vehicle and the vehicle in front canbe reminded that it is insufficient. It is recommended that the rearvehicle should be properly decelerated.
This structure has been awarded the invention patent of Taiwan
with certificate No. I594215 in August 2017.

Figure 2 | System architecture of the proposed system.

(a)

(b)

(c)

Figure 3 | Car attitude. (a) Horizontal, (b) Downhill, (c) Uphill.

K-H. Hsia et al. / Journal of Robotics, Networking and Artificial Life 5(4) 261–264

Figure 4 | Our experimental car for simulation.

263•• If the system is mounted with the automatic brake assisting
system, the brake deceleration can be automatically started in
the case of insufficient safe distance to improve the road safety.
•• With the rear distance detection system, in the case of insufficient safe distance of the rear vehicle, the driver should promptly
accelerate or change the lane to avoid collision in the case ofinconspicuous driving.
•• The technology can also be applied to the automatic following
system, which can keep the distance of vehicles in a safe region toimprove the driver’s acceptance of the following system.
•• In addition to being integrated into the safety design of a new car
to improve the safety factor of the vehicle, the technology can also
be used for retrofitting old vehicles as a driving safety facility.
•• This technology is applicable to the automobile manufacturingindustry and the automobile maintenance industry. The installation on the vehicle can greatly improve the driving safety factor.
•• The technology can also be applied to locomotives or various
types of moving vehicles to improve the safety factor of thevehicle.
This idea has obtained an invention patent of Taiwan. We deeply
believe that a car with this system can be driven more safely.

Figure 5 | An experimental result of dynamic adjustment of safe distance.

4. DISCUSSION AND CONCLUSION
In this paper, we proposed a driving safety system which candynamically adjust the safe distance between vehicles dependingon the speed and weather conditions. This system can be used todetermine and maintain safe distances both in front and rear of acar. Our technology has the following characteristics:•• The safe distance will be automatically adjusted with the speed
and weather conditions. The faster the speed or the poor weatherconditions, the longer the safe distance is.
•• The safe distance will be automatically adjusted with the roadslope. The safe distance of the downhill road will be automatically extended.
•• With the front distance detection system, the vehicle can bealerted when the safe distance is insufficient, to remind thedriver to decelerate properly to avoid the occurrence of chasing.

REFERENCES[1] Freeway Bureau of Taiwan, 2015 National Road Accident
Review Analysis Report, Freeway Bureau, MOTC, Taiwan, 2016,
available from: https://www.freeway.gov.tw/Publish.aspx?cnid=516&p=2849 (cited: September 20, 2018) (in Chinese).
[2] L. Zemanek, J. Prnka, The issue of observance of safe following
distance between vehicles in Germany, Eur. Sci. J. (2015), 448–461 (Special Edition).
[3] D. Qu, X. Chen, W. Yang, X. Bian, Modeling of car-following
required safe distance based on molecular dynamics, Math.
Probl. Eng. 2014 (2014), 1–7.
[4] S.H. Chacon, The effect of driver behavior on freeway traffic flow,
Princeton University, Princeton, New Jersey, 2008.
[5] Road Safety – Speed, available from: http://www.who.int/violence_injury_prevention/publications/road_traffic/world_report/speed_en.pdf (cited: September 20, 2018).
[6] Two-second rule, available from: https://en.wikipedia.org/wiki/
Two-second_rule (cited: September 20, 2018).

Authors Introduction
Dr. Kuo-Hsien Hsia

Mr. Jia-Hong Cai
He is an Associate Professor at the
Department of Electrical Engineering,
Far East University, Tainan, Taiwan. He
received his PhD degree from National
Sun Yat-Sen University, Taiwan in
1994. His research interests include
fuzzy systems, intelligent systems, andtechnical and vocational education.

He graduated from Far East University,Tainan, Taiwan in 2017. He is currently
a graduate student in the Department
of Electrical Engineering, Far EastUniversity, Taiwan. His research interests include micro-chip applications
and intelligent systems.

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Mr. Shu-Li Pai

Prof. Evgeni MagidHe graduated from Far East University,Tainan, Taiwan in 2017. He is currently
working for the Global Learning andAssessment Development, Greater Chinain China. His research interests include
big data, intelligent systems, and internet
applications.

He is currently working as a Head ofIntelligent Robotics Department anda founder, a Professor and the Head ofIntelligent Robotic Systems Laboratory
at Kazan Federal University. He received
his PhD degree from University ofTsukuba, Japan in 2011. His researchinterests include fuzzy systems, intelligent systems, and technical and vocational education.