TECHNICAL PAPER

Research on Relationship between Steering Maneuverand Muscles Activity
T. MIZUNO R. HAYAMA

S. KAWAHARA

L. LOU Y. LIU

X. JI

To operate driver assistance systems (DAS) at optimum efficiency, establishment of a system evaluation method
including behavior of the driver is necessary. In this study, muscle behavior during steering maneuvers has been
investigated in order to create an estimation method of a driver's physical workload and an evaluation method
for DAS. This paper reports on the investigation results of muscle behavior while stabilizing the steering wheel.
Multiple muscles were simultaneously activated corresponding to each steering direction. When CCW direction
torque was generated by the driver, it was observed that the anterior deltoid on right shoulder was activatedfirst. And then, infraspinatus was activated and finally the middle deltoid and pectoralis clavicular muscles wereactivated.
Key Words: steering maneuver, electromyography (EMG), driver's physical workload

1. Introduction
Many driver assistance systems (DAS) adopting
electronic control technology are being put to practicaluse in order to improve safety and energy efficiency.
DAS also contribute to the improvement of vehicle
stability and maneuverability. In particular, electric power
steering systems are expected to advance in the future asimportant role of DAS. Already, due to demands such as
consideration for the environment and maneuverability,
a function to assist steering is adopted in many vehicles.
R&D is being carried out to create new DAS and improveenergy efficiency through the application of this function.
DAS performance impacts on the overall behaviorof the entire system, including maneuvers made by thedriver. A performance evaluation of the overall system
including the driver's maneuver is necessary to alleviate
driver's physical workload and further reduce traffic
accidents.
In quantitative evaluations on steering performance, thedriver inputs of steering angle and torque are measured,as well as vehicle behavior such as yaw rate and lateral
acceleration. These measurements are evaluated basedon correlation with results of subjective evaluations. In
recent years, evaluation methods using the physiologicalindicators of drivers are also being examined. For
example, trials have been performed to evaluate steering
performance by quantitatively measuring driver shoulder*1 This paper was prepared based on the FAST-Zero'11
Proceedings (20117373) hosted by JSAE in 2011.

JTEKT ENGINEERING JOURNAL English Edition No. 1010E (2013)

and upper limb muscle activity with electromyography1)–12)(EMG) .
The authors have investigated muscle activity insteering maneuvers to establish a steering performance
evaluation method and a technique to estimate steering
workload of the driver. With consideration to kinematics
and movement anatomical science during driver steering,
10 muscles able to be measured with EMG were selected.
Moreover, the roles of muscles and features of theiractivation when the driver changes the steering wheel
13)
angle have been shown in previous study .
This paper reports the results of an investigation ofmuscle activity during the subject stabilizes the steering
wheel (hereinafter "Passive Steering"). First, Section 2
describes the muscle selection process and gives an
overview of its results. Section 3 explains the method oftests performed to investigate the role and characteristicsof the selected muscles. Section 4 discusses the order ofmuscle activity at steering. Finally, Section 5 provides anoverall summary.

2. Selecting Muscles for Measurement
Selecting muscles is required in order to investigate
mascle activities involved with driver's steering
4)
maneuvers using EMG. There is a publication which
reports that the anterior deltoid, clavicular portion of
pectoralis major, sternal portion of pectoralis major,
posterior deltoid, middle deltoid, long head of the triceps,
lateral head of the triceps, and biceps are activated. And
also this publication reports that the shoulder muscles are

13

−Research on Relationship between Steering Maneuver and Muscles Activity−

primarily active in the steering maneuver. In this study,measured muscle selected with referral to this publication.
Steering maneuvers, from the perspective ofkinematics, include not only flexion and extension of theupper limb, but also abduction, adduction, supination andpronation. Based on knowledge of movement anatomical
science, teres major and infraspinatus were selected asmeasured muscle. Figure 1 shows the selected muscles
and their positions as well as the related maneuvers.

3. Test Method
A basic test was performed using a Driving Simulator(DS) in order to investigate muscle activities in steering
maneuver. This study aims to clarify the basic propertiesof the steering muscle activation order and examines
steering by the driver to stabilize steering wheel angle

Upper limb movements around the shoulder jointNo

Muscles1

Clavicularportion of
pectoralis
major

★

2

Anteriordeltoid★

Flexion Extension Abduction Adduction Supination Pronation☆

★

3 Middle deltoid
4

Lateral headof the triceps

5

Biceps★

★
☆
★

Sternal portion
6 of pectoralis
major

☆

☆
★

7

Teres major

★

★

8

Long head of
the triceps

★

☆

9

Posteriordeltoid★

10 Infraspinatus☆

3. 1 Test Conditions
Test subjects have been required to sit on a driver's seaton the driving simulator shown in Fig. 2. Here, subjects
stabilized the steering wheel against the triangular
waveform steering reaction torque with an amplitude of 5
Nm and frequency of 0.025 Hz, as shown in Fig. 3. In thisDS, a steering column was mounted in front of a driver
seat imitated a passenger vehicle. Based on the driver's
operations, it was possible to generate steering reaction
torque using a reaction actuator. This DS has good
capability for evaluations of steering systems including
vehicle behavior. In this test, only a function of steering
torque control was used.
The amplitude of 5 Nm was set to be equivalent to thetorque borne by the driver when steering a vehicle with afunction of assisted steering. Moreover, the frequency wasdetermined in quasi-stable range in order to investigate
activation order of muscle activity.
Figure 4 shows the basic posture of the subjects.
Subjects were asked to position themselves so thatthe angle between their forearm and upper arm wasapproximately 110 degrees. A grasping position of righthand on the steering wheel was set at 3 o'clock position.
The left hand was released from the steering wheel. Theview of the DS test is shown in Fig. 5.
The steering wheel angle and torque were measured.
Also, EMG signals related to the abovementioned upper
limb movement were measured. These measurement
results were recorded in a data logger at a sampling
frequency of 1 kHz. The muscles listed in Fig. 1 were
measured. EMG signals were transmitted from a wirelesssensor unit to a logger by radio wave. Since the sensors
were small enough and lightweight, the subject could
maneuver ordinarily and natural operation maneuvers
were realized.

★
★

☆

Fig. 1 Relation between studied muscles and movement ofupper limb and upper arm.
(★Related closely, ☆Related slightly, Blank: No
relation)

14

against disturbance. Passive steering conditions are
similar to steering maneuvers when driving in a straight
line, which accounts for the majority of time spent driving
a vehicle. Therefore this conditions are important in theestablishment of a method to estimate steering workload.

Fig. 2 Driving simulator

JTEKT ENGINEERING JOURNAL English Edition No. 1010E (2013)

Torque, N・m−Research on Relationship between Steering Maneuver and Muscles Activity−

5
4
3
2
1
0
−1 0
−2
−3
−4
−5

4. Test Results

20

40

60

80

100

120

140

Time，sFig. 3 Steering wheel torque from DS

110°

Out of the passive test results, Fig. 6 (A) through (C)show the results of one subject from each group. The X
axis of the graph shows the time, while the Y axis shows(from the top) steering torque, the EMG signals of biceps,
anterior deltoid, middle deltoid, clavicular portion of
pectoralis major, infraspinatus, lateral head of the triceps,
long head of the triceps, posterior deltoid, sternal portionof pectoralis major and teres major. The positive valueof steering torque is the subject's input torque in the CW
direction opposing the torque generated by the DS in the
CCW direction. EMG signals have been processed with a
15 to 500 Hz band path filter and the root mean square has
been applied for 100 samples. (Here, the steady vibrationof the sternal portion of pectoralis major indicates heart
muscle activity).

4. 1 Torque Direction and Muscle Activation

Fig. 4 Basic postureFig. 5 View of DS test

Table 1 Grouping of subject
Group

Description

Number of subjects

A

Experienced

7

B

General7

C

Inexperienced

6

In the CW input by the subject (approx. 15 to 25 s, 45
to 60 s, 85 to 105 s of Fig. 6), the long head of the triceps,
lateral head of the triceps, posterior deltoid and teresmajor were largely activated. Meanwhile, in the CCW
input by the subject (approx. 25 to 45 s, 65 to 85 s, 105 to
115 s of Fig. 6) the clavicular portion of pectoralis major,
anterior deltoid, middle deltoid, infraspinatus and teresmajor were largely activated.
Table 2 is a summary of these results. Results for the
subjects not shown in Table 2 also had the same trend.
Furthermore, no differences were recognized between thegroups, with muscle activation being the same regardlessof driving skill.
Moreover, regardless of the direction of the torque thesteering was opposing, multiple muscles were observed
as being activated at the same time. Therefore it wasobserved that passive steering maneuvers cannot be
achieved with single muscle activity.
There was a trend of the lateral head of the triceps(Fig. 6 (A)) and posterior deltoid (Fig. 6 (C)) being active
when torque was outputted in both directions.

3. 2 Test Subjects
20 subjects aged between 25 and 50 participated in thetest. The subjects was selected based on guidelines shownin Table 1 with consideration to the influence of theirdriving skill on the examination.
Group A consists of subjects who had received driver
training as steering evaluators. Group B consists ofsubjects who drive on a daily basis. Group C consistsof subjects who do not drive daily and have insufficientdriving experience. 7, 7 and 6 subjects were chosen andassigned to Groups A through C respectively.

JTEKT ENGINEERING JOURNAL English Edition No. 1010E (2013)15

−Research on Relationship between Steering Maneuver and Muscles Activity−(v)

Torque(mV) (mV) (mV) (mV) (mV) (mV) (mV) (mV) (mV) (mV)

BicepsAnterior deltoid
Middle deltoid
Clavicular portion of pectoralis major
Infraspinatus
Lateral head of the triceps
Long head of the triceps
Posterior deltoid
Sternal portion of pectoralis major
Teres major
0

20

40

60

80

100

140

120

Time, sGroup A(mV)

Biceps(mV) (mV)(v)

TorqueAnterior deltoid
Middle deltoid(mV) (mV)Clavicular portion of pectoralis major
Infraspinatus

4. 2 Co-contraction Activity
Next, characteristics of muscle activity whenswitching from a CCW maneuver to a CW maneuver
were examined. For example, when CCW steering
torque decreases from around the 30 s mark in Fig. 6,
the activity of the infraspinatus decreases at the sametime as activity of the long head of the triceps increases
in order to generate CW steering torque. At this time,
there is an overlap during which both muscles are
simultaneously active. Figure 7 gives another exampleof the EMG signals of subjects belonging to Group A
at this overlap. These results show that the two muscles
are in a co-contraction relationship and it is believedthat the simultaneous activity of both muscles is noteffective on the steering wheel as steering workload. This
simultaneous activity is believed to be a wasted maneuver
and one of the factors lowering driver steering efficiency.

(mV) (mV) (mV) (mV) (mV)Lateral head of the triceps
Long head of the triceps
Posterior deltoid
Sternal portion of pectoralis major
Teres major
0

20

40

60

80

100

120

Time, sGroup B(v)

Torque4. 3 Activation Order
An evaluation was made of the activation order for themultiple muscles active in the CW and CCW steering
shown in Table 2 in order to study the relationshipbetween these muscles. Figure 8 gives one example ofsuch a relationship. The X axis of the graph shows time
and the Y axis shows EMG signals.

(mV) (mV) (mV) (mV) (mV) (mV) (mV) (mV) (mV) (mV)

BicepsAnterior deltoid

90

Middle deltoid
Clavicular portion of pectoralis major

Lateral head of the triceps
Long head of the triceps
Posterior deltoid
Sternal portion of pectoralis major
Teres major
0

20

40

60

80

100

120

Long head of the triceps

70
EMG signal, %Infraspinatus

50
30
10

140

Time, s

−10
93

98

120

Table 2 Grouping of muscles

Starting point of anterior deltoid activity

MuscleLong head of the triceps
Lateral head of the triceps
Posterior deltoid

1660

Anterior deltoid
Infraspinatus

40
20

Middle deltoid

0

Clavicular portion of
pectoralis major

Starting point of infraspinatus activity
Starting point ofclavicular portion of
pectoralis major activity

80

Anterior deltoid

Infraspinatus
CW & CCW torque

EMG signal, %100

CCW torque

113

108

Fig. 7 Example of co-contraction

Fig. 6 Example of EMG signals in passive steering maneuver

CW torque103
Time, sGroup CTorqueInfraspinatus

Overlap

Clavicular portion of pectoralis major
50

55

60

65

70

75

Time, sFig. 8 Examples of activation starting time

Teres major

JTEKT ENGINEERING JOURNAL English Edition No. 1010E (2013)

−Research on Relationship between Steering Maneuver and Muscles Activity−

The muscle activation order in a CW maneuver was
evaluated. Using the point where the EMG signal of
the lateral head of the triceps increased as a reference,a reading was made to ascertain the delay before other
EMG signals began to increase. Figure 9 shows theresults of this reading. The X axis shows which muscles
are active in a CW maneuver, and the Y axis shows thedelay in each muscle activity starting to increase. The
bar graph shows the delay of each subject, and the line
graph shows the average delay of subjects from eachgroup. These results demonstrate that, in the case of CW
maneuvers, there are no obvious trends regarding muscle
activation. Moreover, no significant difference wasobserved between subject groups.

4. 3. 2 Muscle Activation Order at CCW Maneuver
Next, the muscle activation order in a CCW maneuver
was evaluated. Using the point where the EMG signal of
the anterior deltoid increases as a reference, a reading was
made to ascertain the delay before other EMG signals
began to increase. Figure 10 shows the results of thisreading. Each axis and graph is the same as the evaluation
results of CW maneuvers.
The results of this evaluation showed that, unlike
CW maneuvers, there were drivers which had differingmuscle activation orders, however, it was observed that
under these conditions muscles were activated in theorder shown in Table 3. In addition, because this same
trend was common to the different subject groups, thetest showed that the same muscle control was performed
regardless of driving skill. Furthermore, the anteriordeltoid, infraspinatus, middle deltoid and clavicularportion of pectoralis major are activated by movement of
the shoulder joint, while the biceps are activated by theelbow joint. Hence, it can be claimed that subjects first
tried stabilizing steering against the changing steering

No.1
No.6
No.11
No.16
Group (A)

No.2
No.7
No.12
No.17
Group (B)

No.3
No.4
No.8
No.9
No.13
No.14
No.18
No.19
Group (C)

No.5
No.10
No.15
No.20

5. Summary
This paper investigated the roles and characteristics
of muscle behavior for stabilizing the steering wheelwith a passive steering maneuver, in order to establish
an evaluation index of the driver's workload on steering
maneuver. With the research, the following conclusions
can be drawn:1) Different muscles are activated depending on thesteering torque direction. For either direction of torque,multiple muscles are active simultaneously as opposed
to individual muscle activity. Complex muscle control
is performed by the subject.
2) When the direction of torque changes, the activatedmuscles change. This change does not happen
instantaneously. There is an overlap where either
muscle is active. This co-contraction activity in theoverlap does not generate effective torque on thesteering wheel and may be a factor in lowering driversteering efficiency.
3) In order to stabilize the steering wheel against torqueforcibly applied in the CCW direction, the drivergenerates torque in the CW direction. At this time, thelong head of the triceps, the lateral head of the triceps
No.1
No.6
No.11
No.16
Group (A)

No.2
No.3
No.4
No.7
No.8
No.9
No.12
No.13
No.14
No.17
No.18
No.19
Group (B)Group (C)

No.5
No.10
No.15
No.20

12
10
8
6
4
2
0
Anterior deltoid−2

8Infraspinatus

Middle deltoid

Clavicular portion of
pectoralis major

Biceps−4

6

Fig. 10 Activation order in CCW maneuver

4
Delay, swheel torque by increasing the rigidity of their should
joints. Then subjects compensated for any insufficiencies
with activation of their elbow joints.

Delay, s

4. 3. 1 Muscle Activation Order at CW Maneuver

2

Table 3 Activation order0
Lateral head

−2 of the triceps

Long headof the triceps

Teres major

Posterior deltoid

−4
−6
−8

Fig. 9 Activation order in CW maneuver

JTEKT ENGINEERING JOURNAL English Edition No. 1010E (2013)

Activationorder

Muscles1

Anterior deltoid

2

Infraspinatus

3

Middle deltoid
Clavicular portion of pectoralis major

17

−Research on Relationship between Steering Maneuver and Muscles Activity−

and the posterior deltoid are activated. In this study,
there was great variation in the muscle activation
order between subjects, therefore no obvious common
characteristics were observed.
4) In order to stabilize the steering wheel against torqueforcibly applied in the CW direction, the drivergenerates torque in the CCW direction. At this time,
the anterior deltoid is activated first, followed by
the infraspinatus, the middle deltoid and finally theclavicular portion of pectoralis major. This shows that,at first the driver tries to stabilize the steering wheel by
improving the rigidity of their shoulder joint, and thenimproves the rigidity of their elbow joint against any
extra torque generated.
Biometrics such as EMG is useful in estimating thedriver's physical workload. But there are also expectations
that it may play a role in the active safety technology
field relating to steering such as accident prevention anddetection of driver's intention.

References
1)

2)

3)

4)

5)

6)

7)

8)

18

Cole D. J.: Steering feedback Mathematical simulationof effects on driver and vehicle. ATZ autotechnology, 8,(2008) 2.
Pick A. J., Cole D. J.: A mathematical model of driversteering control including neuromuscular dynamics.
Journal of Dynamic Systems, Measurement, and Control,
130(3), (2008) 9.
Keen S. D., Cole D. J.: Steering control using model
predictive control and multiple internal models. The 8 thInternational Symposium on Advanced Vehcle Control,
Taipei, China, (2006) AVEC060095.
Pick A. J., Cole D. J.: Measurement of driver steering
torque using electromyography. Transactions of the
ASME. 2006, 128 (2006) 960.
Pick A. J., Cole D. J.: Neuromuscular dynamics and thevehicle steering task. In proceedings of the 18 th IAVSD
Symposium on the Dynamics of Vehicles on Roads andTracks, Japan, August 2003, Vehicle System Dynamics,
41(Suppl.) (2003) 182.
Pick A. J., Cole D. J.: Dynamic properties of a driver's
arms holding a steering wheel. Proc. Inst.Mech. Eng.,Part D (J. Automobile Engineering), 221(12) (2007)
1475.
Pick A. J., Cole D. J.: Neuromuscular dynamics in thedriver-vehicle system. Vehicle System Dynamics, 44(2006) 624.
Pick A. J., Cole D. J.: Driver steering and muscle activity
during a lane-change manoeuvre. Vehicle System
Dynamics, 45(9) (2007) 781.

9)

Akira Kuramori, Noritaka Kouguchi., Kojiro Ishikawa,
Masayoshi Kamijo, Tsugutake Sadoyama: Evaluationof effects of drivability on driver workload by using
electromyogram. JSAE review, 25(1) (2004) 91.
10) Takamitsu Tajima, Toru Oshima: Effect of improvementof steering system of vehicle based on muscular
cooperated control model. Proc. Inst. Mech.Eng., Part D(J. Automobile Engineering), 221(12) (2007) 1475.
11) Akira Kuramori, Noritaka Kouguchi, Masayoshi Kamijo,
Tsugutake Sadoyama: Evaluation of vehicle drivability
by using muscle activity of drivers. 2003, 6 th JSEK
conference.
12) Akira Kuramori, Noritaka Koguchi, Masayoshi Kamijo,
Tsugutake Sadoyama: Study on Driving Ease Evaluation
Focusing on Muscular Activity of Driver. Journal ofSociety of Automotive Engineers of Japan, 61(6) (2007)
116.
13) Liu Yahui, Ji.Xuewu, Ryouhei Hayama, Takahiro
Mizuno, Sadahiro Kawahara, Lou Liming: Research
on EMG Signals of Shoulder and Upper Limb Muscles
within Steering Maneuvre - Part 1:Identification of theMain Muscles and Their Roles, JSAE FAST-Zero'11
Proceedings (2011) 20117372.

T. MIZUNO*

L. LOU****R. HAYAMA** S. KAWAHARA***Y. LIU*****X. JI******

Advanced Fundamental Research Dept., Research &Development Headquarters** E l e c t ro n i c S y s t e m s R & D D e p t . , R e s e a rc h &Development Headquarters, Doctor of Informatics*** M e ch a n i c a l S y s t e m s R & D D e p t . , R e s e a rch &Development Headquarters**** Advanced Fundamental Research Dept., Research &Development Headquarters, Doctor of AgriculturalEngineering**** Department of Automotive Engineering, Tsinghua*
University

JTEKT ENGINEERING JOURNAL English Edition No. 1010E (2013)