DESIGN AND EXPERIMENTAL VERIFICATION OF

POWER-ASSISTED SMART DOOR SYSTEM FOR PASSENGER

VEHICLE

Kum-Gil Sung, Min-Kyu Park

School of Mechanical and Automotive Engineering Technology

Yeungnam College of Science and Technology, Daegu 705-703, Korea

Byoungsoo Lee

Department of Mechnical and Automotive Engineering, Keimyung University, Daegu 704-701, Korea

Keywords: Smart Door, Power-assist, Passenger Vehicle, Human Friendly.

Abstract: In this study, to enhance the ease of opening and closing the doors of the passenger vehicle, a smart door

with a power assist mechanism consisting of a motor and clutch was developed and tested. A power assist

mechanism mounted within the vehicle’s door is proposed and modeled. The required force necessary to

control the designed mechanism during the vehicle’s roll, pitch and the opening angle of the door has been

established. Finally, the improvement in the ease of opening and closing doors by utilizing the designed

ower assist mechanism was tested and proven through an experimental verification.

1 INTRODUCTION

Recently, in the automotive industry, research in

creating intelligent parts by integrating various

functions is actively conducted. The developed

technologies are being commercialized rapidly in

North America, Europe, and Korea. Among such

intelligent parts, auto sliding door and electric power

door systems are developed for doors of vehicles

(

Yoon, 2002, Grujicic, 2009). However, in most of the

conducted research and products in the process of

commercialization, studies on mechanisms for

compensating changes in the necessary force to open

and close doors of a vehicle parked at an angle is

limited.

Depending on the structure, shape, and opening

& closing force of the vehicle’s door, the perceived

convenience and safety by the user is affected

greatly and it is very frequently used by passengers.

Thus, when the door does not operate as intended by

the passenger, the inconvenience is drastically felt.

Traditionally, a part called the door checker which is

attached between the door and the vehicle frame

prevented the door from opening instantaneously

when the vehicle is parked at an angle.

However, in limited space or when the vehicle is

parked at an angle forward or sideways due to the

weight of the door it will not become stationary at

the passenger’s desired position. Therefore, a new

power-assist smart door which adjusts the opening

and closing force depending on the roll and pitch

angle of the vehicle is suggested. It utilizes a motor

and clutch to power-assist the passenger while

opening or closing the door of the vehicle. When

this system is used no matter how the vehicle is

positioned the door can be conveniently opened or

closed without exerting oneself. The convenience of

this kind of a system becomes more important when

the weight of the door is heavy or for large

passenger vehicles. In order to commercialize such a

power-assist smart door system, in depth research in

various areas such as power assist mechanism,

controlling the opening and closing force,

mechanism for understanding the intention of the

passenger, dedicated motor and clutch development

must be conducted. Among these, for developing the

power-assist equipment, the mechanism for

understanding the passenger’s intention when

getting on or off the vehicle and to actively control

the necessary force to open or to close the door must

382

Sung K., Park M. and Lee B. (2010).

DESIGN AND EXPERIMENTAL VERIFICATION OF POWER-ASSISTED SMART DOOR SYSTEM FOR PASSENGER VEHICLE.

In Proceedings of the 7th International Conference on Informatics in Control, Automation and Robotics, pages 382-386

DOI: 10.5220/0002941703820386

 SciTePress

be organized.

In this study, to enhance the ease of opening and

closing the doors of the passenger vehicle, a smart

door with a power-assist mechanism consisting of a

motor and clutch is developed and a smart door with

this mechanism will be designed. A power assist

mechanism which can be mounted inside the door is

suggested and modeling of a vehicle door with this

mechanism conducted. Based on this, a power assist

mechanism which is suitable for passenger vehicle is

designed. A computer simulation is used to derive

the necessary force to open or close the door for a

given door opening angle at a given vehicle roll or

pitch angle.

2 MODELING OF SMART DOOR

An illustration of the new power assist smart door

which can alter the necessary force to change the

force required to open or close the door when the

vehicle is parked at a roll or pitch angle is provided

in Figure 1. It consists of a rack and pinion, a clutch,

and a reduction gear and motor. When this

mechanism is applied, even when the vehicle is

parked at an angle, the necessary force required to

open or close the door will be the same as if the

vehicle is parked on a flat level surface.

To establish the equation of motion for the

power-assist mechanism attached smart door, in the

model, as shown in Figure 2, the degrees of freedom

was established by the roll



and pitch



angle of

the vehicle and the angle of the door opening



. The

equation of motion is derived based on moment

from the weight of the door and the assumption that

the external force generated moment by the power

assist mechanism.

Initially, as indicated in Figure 3 to obtain the

moment of the door due to its own weight, it is

assumed that the roll and pitch angle of the vehicle

frame is fixed and that the roll and pitch

angle(actually the reverse direction of the vehicle

frame angle) is created relative to the gravity vector.

Thus, the moment by the door’s own weight

can

be summarized as the following.

rotgg

gmrT



(1)

Here,

rot

is the rotated gravity vector caused by

the roll and pitch angle and can be represented as

equation (2).

















rot





sin

sincos

cossin

(2)

When equation (1) is reorganized by the y

directional component, the moment in the y

direction by the weight of the door becomes the

following equation.

Clutch, Reduction Gear

and Motor

Rack

Pinion

Figure 1: The configuration of the power-assist

mechanism for the proposed smart door system.





Figure 2: Coordinates for the dynamic model.



Figure 3: Gravity vector considering the roll and pitch

angle of vehicle body.





xxzgyg

mgrT









sincoscossinsin 



(3)

Next, as indicated in Figure 4 the moment of the

door

created by force of the power assist

mechanism(

) is arranged as equation (4).

DESIGN AND EXPERIMENTAL VERIFICATION OF POWER-ASSISTED SMART DOOR SYSTEM FOR

PASSENGER VEHICLE

383

tgF

erFFrT



(4)

Here,

is the directional unit vector created by the

power assist mechanism and can be represented as

the following.



cos

0/cos sin

sin

txz

err



 

















(5)

The following equation is the rearrangement of





rot

Figure 4: Free body diagram for dynamic model of the

proposed smart door system.

the moment in the y direction of the door caused by

the power assist mechanism from equation (4).





sincos

cossin











(6)

When equation (2) and (6) is applied to the

equation of motion it becomes the following.

(sin cos)

(cos ) (sin )

(sin sin cos cos sin )

yFygyfric

zx xfric

JcTTT

rmg T





 

  

  





 



 

(7)

Here,

is the mass moment of inertia in the

y direction,

is the damping coefficient of the door

hinge, and

fric

T is the frictional force that occurs

when the door opened or closed.

3 DESIGN AND MANUFACTURE

OF SMART DOOR

In order to design the power assist mechanism which

will be actually mounted in the vehicle, it becomes

necessary to estimate the maximum force necessary

to open or close the door of the vehicle when it is in

a pitch or roll position. Depending on the door

opening position the desired control force

des

F must

be estimated. In this mechanism, the maximum force

needed to open or close the door during a vehicle’s

pitch or roll position can be measured

experimentally, however, the required control force

of the mechanism must be set up depending on the

pitch, roll, and door angle. As indicated in Figure 5,

in this research, to set up the control force of the

pitch, roll, and door opening angle the respective

dynamic frictions

F and

F have been measured.

Then the average value has been calculated and the

control force has been set up as shown in Figure 6.

Thus, as shown in Figure 5(a) only the forces needed

to open or close the door when the vehicle is on

level ground(

des



and

des

 ) is required for

vehicle in a slanted position as indicated on Figure

5(b).

The required control forces for roll



, pitch



and door opening angle



are within the range of -

30~30

°, -50~50° and 0~80° respectively as shown

in Figure 6. As it can be verified from the results the

required maximum control force is approximately

1486.3N.

In this study the maximum required control force

is used as the boundary condition for the design and

the motor, reduction gear, rack and pinion, and

selection of parts were conducted.

des

Kinetic

Friction Force

Static

Friction Force

(a) case I (flat road)

Kinetic

Friction Force

Static

Friction Force

des

(b) case II (slope road)

Figure 5: The desired actuating force with respect to the

vehicle body angle.

ICINCO 2010 - 7th International Conference on Informatics in Control, Automation and Robotics

384

Desired Force

Figure 6: The required control force characteristics for

designing power-assist device.

Figure 7: Power-assist mechanism control board.

In order to manufacture a suitable smart door, the

door of an actual vehicle has been measured and the

parameters are indicated. Based on these values, a

control block diagram to control the smart door

system is structured. The power assist mechanism

control board is shown in Figure 7 and it is attached

to the smart door system.

4 EVALUATION OF SMART

DOOR

To test and evaluate the designed smart door, the test

set up indicated in Figure 8 is constructed. An actual

door of a passenger vehicle is attached to the frame.

This frame can be set up in a vehicle roll position.

The force generated by the power assist system is

controlled by the computer D/A signal, the vehicle

roll angle



, door opening angle



, and angular

velocity





are measured by using sensors.

In order to investigate the characteristics of the

smart door system, the roll angle of the vehicle was

set at 15

° as indicated in Figure 8 and the required

opening and closing forces are actually measured.

As it can be found from the experiment in Figure 9

when the door opening angle is adjusted between

0~80

° if the power assist mechanism is not

activated, the necessary force is 60~180N. But when

the power assist mechanism is activated

approximately 20~80N was required to open or

close the door.

5 CONCLUSIONS

In this study, to enhance the ease of opening and

closing the doors of the passenger vehicle, a smart

door with a power assist mechanism consisting of a

motor and clutch was developed and tested. For this

purpose a power assist mechanism which can be

mounted inside the door is suggested and the smart

door is modeled and tested. The required control

force for controlling the mechanism due to the

vehicle’s pitch, roll, and door opening angle is

established.

Figure 8: Experimental setup for the power-assisted smart

door system.

0 20406080

100

150

200

w/o power-assist

with power-assist

Force (N)

Door O

en An

(

Figure 9: The control responses of the smart door system.

Based on the established results the power assist

mechanism with the adequate opening and closing

force was designed. A computer simulation was

used to evaluate the designed power assist

DESIGN AND EXPERIMENTAL VERIFICATION OF POWER-ASSISTED SMART DOOR SYSTEM FOR

PASSENGER VEHICLE

385

mechanism. The designed power assist mechanism

installed smart door will be mounted on a vehicle

and will be tested in the near future to prove the

usefulness and convenience of the system.

REFERENCES

Grujicic, M., Arakere, G., Sellappan, V., Ziegert, J. C.,

Kocer, F. Y., and Schmueser, D., 2009. Multi-

Disciplinary Design Optimization of a Composite Car

Door for Structural Performance, NVH,

Crashworthiness, Durability and Manufacturability. In

Multidiscipline Modeling in Materials and Structures.

Vol. 5, No. 1, pp. 1-28.

Yoon, D. H., Lee, J. H. and Yoo, J. H., 2002.

Development and Optimization of Automobile Parts

for Door Opening Angle Control System. In

Proceedings of the KSAE Annual Spring Conference.

pp. 1235~1240.

ICINCO 2010 - 7th International Conference on Informatics in Control, Automation and Robotics

386