Development of 8х8 All-terrain Vehicle with Individual Wheel Drive

Alexander Belyaev

, Sergey Manyanin

, Anton Tumasov

, Vladimir Makarov

and Vladimir Belyakov

Transport Systems Institute, Nizhny Novgorod State Technical University n.a. R.E. Alekseev,

Minin St., 24, Nizhny Novgorod, Russian Federation

LLC Transmash, Cherepichny village, 3, Nizhny Novgorod, Russian Federation

Keywords: Multifunctional All-terrain Vehicle, Hydrostatic Transmission Driveline, Efficiency, Fuel Consumption.

Abstract: In this article, we consider the problem of developing a rational competitive design of a multifunctional all-

terrain vehicle (MATV) with 8х8 axle configuration. Empirical dependencies are proposed to calculate

weight-size parameters of these vehicles, such as power and power-to-weight ratio, payload, maximum speed,

average ground pressure depending on full vehicle weight. Key dependencies are provided to calculate

hydrostatic transmission (HST) parameters used to determine hydraulic unit sizes and connection diagrams.

Various HST control algorithms are analyzed in order to increase efficiency and reduce fuel consumption.

The results show that the right HST control algorithm can increase efficiency by 10%, and reduce fuel

consumption by 18%. General view of the developed MATV is provided.

1 INTRODUCTION

Most of the Russian territory is characterized by

rather poor road infrastructure. These un- and

underdeveloped areas are hard to reach but very

promising in terms of mineral and hydrocarbon

production. A study shows that individuals and

companies in Russia purchase around 700 – 750

new vehicles annually. The market is dominated by

4х4 and 6х6 all-terrain vehicles. 8х8 modifications

account for just 20% of all sales, but they are as

good off-road as tracked vehicles, and less

destructive to the tundra soil. Individual wheel drive

and the right control algorithms for each wheel

ensure the best cross-country abilities, highest

efficiency and lowest emissions.

Therefore, in this article we consider the

problem of developing a rational competitive design

of a 8х8 vehicle with individual wheel drive.

Possible algorithms for power distribution flow

control in hydrostatic transmission are analyzed.

2 CALCULATION OF

WEIGHT-SIZE PARAMETERS

We have analyzed the key parameters of current

multiaxial all-wheel drive vehicles with 8х8 axle

configuration and obtained basic relations for

weight, power and speed characteristics

(Barahtanov et al., 2015) Table 1 contains

regression equations for all-terrain vehicles, trucks

and special purpose vehicles.

Recommended parameters for the developed all-

terrain vehicle are listed in Table 2. Full vehicle

weight served as an initial parameter. The reason for

such choice is that all-terrain vehicles with 8-9 t full

weight have an insignificant market share in Russia.

All analogs of the developed multiaxial vehicle

on ultra low pressure tires are equipped with manual

transmission (reducers, cardan shafts, etc.) But it is

not enough for cross-country conditions. Such

vehicles require infinitely variable automatic

transmission combining individually regulated

power actuators for each wheel with automatic

control system. Efficient torque adjustment helps

each wheel to achieve maximum traction on low-

load-bearing capacity soils. Skid control system for

each wheel ensures maximum traction force and

minimum road resistance.

Current multiaxial wheeled vehicles are

equipped with electromechanical (for example,

NEMTT-AZ by Oshkosh, 6х6 multipurpose vehicle

by QinetiQ, 8x8 experimental prototype BAZ-

М6910E) and hydrostatic transmission (HST). The

best-known Russian vehicle with hydrostatic

transmission is three-axle vehicle «Gidrohod-

556

Belyaev, A., Manyanin, S., Tumasov, A., Makarov, V. and Belyakov, V.

Development of 8x8 All-terrain Vehicle with Individual Wheel Drive.

DOI: 10.5220/0007765505560561

In Proceedings of the 5th International Conference on Vehicle Technology and Intelligent Transport Systems (VEHITS 2019), pages 556-561

ISBN: 978-989-758-374-2

Table 1: Regression equations for design parameters of 8х8 vehicles.

Dependencies Vehicle type Formula

Engine power from full vehicle weight, [kW - t]

All-terrain Pe = 15 Ma + 13

Trucks Pe = 4 Ma + 135

Special purpose Pe = 13 Ma + 21

Power-to-weight ratio from full vehicle weight, [kW/t - t]

All-terrain

pe = 27-5 ln(Ma)

Trucks

Special purpose

Payload from full vehicle weight,

[t - t]

All-terrain Mг = 0,3 Ma

Trucks Mг = 0,8 Ma - 9,1

Special purpose Mг = 1

Maximum speed from full vehicle weight, [km/h - t]

All-terrain Vа = 38 Ma0,3

Trucks Vа = 80

Special purpose Vа = 38 Ma0,3

Average ground pressure from full vehicle weight, [kPa - t]

All-terrain p = 0,6 Ma + 5,4

Trucks p = 1,.3Ma + 25,1

Special purpose p = 1,6 Ma + 14

49061» developed by the Central Scientific

Research Automobile and Automotive Engines

Institute «NAMI» (Belyakov et al., 2018). In

Russia, the most common type of infinitely variable

automatic transmission is hydrostatic transmission.

Table 2: Recommended vehicle parameters.

Parameter

Recommended

value

Full weight, t 8-9

Payload, t min. 3

Powe

-to-weight ratio, kW/t max. 15

Maximum speed, m/s min. 70

Average ground pressure, kPa 10.2-10.8

3 MATHEMATICAL MODEL OF

THE VEHICLE WITH

HYDROSTATIC

TRANSMISSION

HST parameters are determined basing on the

traction-speed calculation. The ability rating is

calculated from the following dependence

(Belyakov et al., 2018):





ксa

ммммпотпнрмрм

ксa

zqpppi

maxmax

max

102











vehicle speed is calculated from the formula

(Belyakov et al., 2018):



min

max

max e

max

377.0

нм

Vнрмрн

кс

Vннн

qzii

rqz









where  – vehicle speed; 

; 

– number of pumps,

motors; 



– angular velocity of the motor; 

; 

– pump volume, motor volume; 

кс

– rolling radius;



– pump pressure; Δ

пот

– pressure drop in the

hydraulic circuit; 

– charge pressure; 

– vehicle

weight; 

рн

, 

рм

– pump, motor reducer ratios, 

рп

;



, 

рм

– efficiency factor of pump reducer,

pump, motor, motor reducer.

Calculation results helped to define typical sizes

of hydraulic units and connection schemes

(SHuhman et al., 2007). We have selected a

hydrodifferential scheme with individual control,

two 125 cm3 pumps and eight 107 см3 motors.

Transmission scheme is shown in Figure 1.

A Matlab/Simulink model has been developed

for initial HST configuration and adjustment. The

basic equations for hydraulic unit parameters are

given below.

For the pump:

– torque





ннн

Tpq







– discharge

ннн





For the motor:

– torque





ммм







qpT

– discharge

ммм







Development of 8x8 All-terrain Vehicle with Individual Wheel Drive

557

Figure 1: Structural transmission scheme.

– pressure drop of the working fluid in

pumping and draining lines of hydraulic units,



– volume efficiency factor of the pump and the

hydraulic motor.

Torque distribution on motor shafts is calculated

from the following formula (Belyakov et al., 2018):

 ::::::

3м2м1м3м2м1м

qqqTTT 

Angular velocities of hydraulic motors are

calculated from the dependence (Belyakov et al.,

2018):



3м3м2м2м1м1мн

ωωω qqqQ

Torque from the hydraulic pump applied to the drive

wheel is used to overcome rolling resistance,

accelerate the wheel and implement traction. The

general equation of wheel dynamics is given below:

сопрммм

TiTI







The rotation resistance torque is determined by the

rolling resistance torque and the torque generated by

the tangential component of the wheel-soil

interaction force:

)()(

сопр xz

RTRTT 

A model from the works (SHuhman et al.,2007);

(Belousov et al., 2013); (Kurmaev, 2009) served as

a basis for HST operation model for multiaxial

vehicle.

The calculations presented above make it

possible to analyze the HST parameter control

algorithms in order to achieve maneuverability,

cross-country ability and power efficiency targets in

off-road conditions reflecting the factors that

influence vehicle operational parameters. Slip

control ensures maximum traction force and

minimum rolling resistance.

To select rational settings for HST control

system, we have analyzed various control

algorithms (Lepeshkin, 2012); (Gorelov et al.,

2012); (Kotiev et al., 2012); (Gorelov et al., 2011);

(Serebrennyj, 2009):

- slip control algorithm for the side wheels based

on the known linear velocity of MATV chassis'

center of inertia;

- «high-threshold» control algorithm for the side

wheels of MATV chassis (with angular

acceleration limitation);

- slip control algorithm based on the average

rotation velocity of MATV chassis' side wheels.

We have simulated MATV movement on various

surfaces and performed virtual tests on high

VEHITS 2019 - 5th International Conference on Vehicle Technology and Intelligent Transport Systems

558

adhesion roads followed by low adhesion roads, and

tests on high adhesion surfaces with alternating low

adhesion surfaces. The most challenging surface for

HST control system is the «mixed» road surface

with random parameter setting. For simulation, we

have set a combination of snow and soil surfaces

with characteristics assigned according to the

normal law of distribution. Examples of wheel slip

changes for MATV simulation w/o control system

(on the left) and w/ control system (on the right) are

indicated in Figure 2. Changes in efficiency, power

demand and fuel consumption for MATV

simulation w/ control system are shown in Figure 3.

The curves in Fig. 2 and 3 show that

implementation of control system reduces slipping,

increases efficiency, and cuts power loss related to

movement and fuel consumption. In this case, the

most relevant characteristics are efficiency and fuel

economy. Now we shall determine which control

algorithm is more suitable for the developed

MATV.

4 EFFICIENCY AND FUEL

ECONOMY EVALUATION

To evaluate power efficiency, we use the value

equal to the ratio of «effective» traction work

applied to the wheels to the «performed» work of

Figure 2: Examples of wheel slip curves for MATV simulation w/o control system (on the left) and w/ control system (on the

right).

Figure 3: Examples of efficiency, power demand and fuel consumption curves for MATV simulation w/o control system (on

the left) and w/ control system (on the right).

Development of 8x8 All-terrain Vehicle with Individual Wheel Drive

559

the input torque.

Efficiency of MATV wheel drive control

algorithms should be estimated in HST operation

simulation w/o the parameter control system. This

will ensure qualitative assessment.

Since the estimated parameters take on different

values at any time, they should be considered as an

integrated measure in the course of vehicle

movement. Otherwise, dependencies for the

variable processes will be defined based on the

following dependencies:

– for efficiency





эф

dtKK

инт

эф

where

эф

– efficiency factor at any time,

– total

movement time.

– for fuel economy





dtQQ

инт

эф

Changes in efficiency and fuel consumption on the

«mixed» road surface w/ HST control system using

different control algorithms are presented on the

diagram in Fig. 4.

5 DATA ANALYSIS

Basing on the results of computer simulation, we

can judge the efficiency of the developed control

algorithms for the hydrostatic wheel drive. The

higher variability of the surface parameters, the

higher the HST control system efficiency. For

example, for step change of the parameters typical

for the high adhesion surface followed by a low

adhesion area, increase in efficiency and drop in

fuel consumption amount to just tenths of a

percentage point. For the high adhesion surfaces

with alternating low adhesion surfaces, efficiency is

increased by 3-5 %, and fuel consumption is

reduced by 8-14 % depending on the selected

control algorithm. For the «mixed» surface,

efficiency is increased by 5-10 %, and fuel

consumption is decreased by 11-18 % depending on

the selected control algorithm.

It should be noted that for actual operating

conditions of MATV the most suitable surface is the

«mixed» one. It means that the developed control

algorithms will not just boost maneuverability, but

also increase HST efficiency by 10% and reduce

fuel consumption by 18%.

Figure 4: Incremental efficiency factor and decremental

fuel consumption diagram for the «mixed» road surface

w/ HST control system using different control algorithms.

Figure 5: General view of MATV.

6 PRACTICAL

IMPLEMENTATION

The calculations served as a basis for MATV

development. General view of the vehicle

(Belyakov et al., 2018);y(

Belyakov et al., 2015) is

presented in Fig. 5. The technical characteristics

correspond to the calculations. The vehicle will be

manufactured by LLC Transmash

(http://www.transmashnn.ru/).

7 CONCLUSIONS

– layout schemes and design options for 8х8

vehicles have been analyzed.

– statistical dependencies for multiaxial vehicles,

boundaries of rational parameters for

development of a competitive MATV have been

obtained: full weight 8-9 t, min. payload 3 t,

max. power-to-weight ratio 15 kW/t, average

ground pressure 10.2-10.8 kPa.

– implementation of infinitely variable hydrostatic

transmission in the Russian vehicles has been

VEHITS 2019 - 5th International Conference on Vehicle Technology and Intelligent Transport Systems

560

motivated.

– various HST control algorithms have been

analyzed: algorithm based on the known linear

velocity of center of inertia, «high threshold»

algorithm for the side wheels of MATV chassis

(with angular acceleration limitation), algorithm

based on the average rotation velocity of the side

wheels.

– the results have showed that depending on the

selected control algorithm and operating

conditions, efficiency increases by 10 %, and

fuel consumption falls by as much as 18 %.

– theoretical research presented in the paper has

been implemented in the MATV manufactured

by LLC Transmash.

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