The simulation of truck motions

S~ptember 1985

by

_{2 DEC.}

₁

₉₈₉

L. D. Reid and M. A. Nahon

Bibliotheek TU Delft

Faculteit der Luchtvaart-en Ruimtevaarttechniek Kluyverwag 1

2629 HS Delft

UTIAS Report No. 294

eN

ISSN 0082-5255

,.

by

L. D. Reid and M. A. Nahon

Subrnitted January 1985

September 1985

Bibl iotheek TU Delft L~,P

1111111111111

C 2180318

UTIAS Report No. 294 CN ISSN 0082-5255

Abstract

A study was carried out to evaluate the ability of the UTIAS simulator facility to represent the motion environment experienced by a truck driver while performing typical driving maneuvers. Software was developed to comrnand simulator motions in response to a truck model computer program provided by the Ontario Ministry of Transportation and Communications.

Measurements of translational acceleration and rotational velocity generated by the simulator1s motion drive system were obtained. The predicted driver motion sensations in the truck and in the simulator were generated by a vestibular model and were compared with favorable results.

Acknow1edgements

This stl1dy was prepared with the support of the Research and Deve10p-ment Branch of the Ontario Ministry of Transportation and Communications under the Ontario Joint Transportation and Communications Research Frogramme, Contract No. 31626.

Abstract Acknowledgements Notation 1. Introduction 2. Vestibular Models CONTENTS

2.1 Rotational Motion Sensation 2.2 Specific Force Sensation 3. Simulator Facility

3.1 Motion Base Hardware 3.2 Motion Sensing Package

1 3 3 4 7 7 7 3.3 Simulator Motion Base Drive Algorithm 8

3.3.1 Translational Motion Channel 9

3.3.2 Rotational Motion Channel 10

3.3.2.1 Simulation of Vehicle Rotational Velocity 10

3.3.2.2 Tilt-Coordination 11

3.3.3 Actuator Length Calculations 13

4. Motion Base Test Runs 15

4.1 Simulated Maneuvers 15 4.2 Modifications to MTCSIM 16 4.3 Program TRUCK 4.3.1 Function 4.3.2 Method 16 16 17

4.3.3 Inputs and Outputs 18

4.4 Washout Filter Selection and Trial Run Results 19 4.4.1 Double Lane Change Washout Filters 20 4.4.2 Braking and Constant Rate Turn Washout Filters 22 4.4.3 Trial Runs on the UTIAS Simulator Facility 23

5. Summary Tables Figures Appendix

Notation* a ..., a. -1 ~l , a2 A· -p1

- translational inertial acceleration

translational inertial acceleration of the origin of Fi - intermediate acceleration variables

- the location of the upper motion base bearing blocks relative to the centroid of the pattern.

B· - the location of the lower motion base bearing blocks relative ~1

f f.

,.1

to the centroid of the pattern. - specific force

the specific force at the origin of F. 1 il,f2,fL - intermediate specific force variables

~ - acceleration due to gravity

K otolith or transfer function gain

Kx,Ky,Kz - sealing factors

l. ₇₁ - ith actuator length vector

L - Jength of the actuator when at one half the maximum extension ~IS - transformation matrix from F_S into F_I

T [p.,q.,r.]

1 1 1 - angular velocity of Fi

R _{- the location of FPa (Fps}) with repseet to FA (F S)

s - the Laplace variable

S the location of the origin of F_S with respect to the origin of F I• Ta,Tb,TL,Ts - vestibular model parameters

TS - angular velocity transformation matrix

~i

=

[~iei~iJT

- the Fi frame Euler angles

eSH,SSL - intermediate variables

~SL,eSL - tilt-coordination angles

w - angular velocity

...

* The International System of Units is employed in this report. Angular measure is given in degrees in all figures while radians are employed in the computer programs.

T

w.

=

[p.q.r.] - angular velocity of F.

-1 1 1 1 1

w2 - filter break frequency

X "7'

,.

x

-x

.

x - a vector

- a matrix or a column matrix representation of x - the transpose of x

- sensed value of x - Laplace transform of x - dx/dt

~ •

Plotting Notation AXPA TRK, AYPA TRK

- the translational tnertial acceleration of the truck driverls head in FA components.

AXSI SIM, AYSI SIM, AZSI SIM

- the translational inertial acceleration of the origin of the simulator F

S in FI components.

FXAA TRK, FYAA TRK, FZAA TRK

- the specific force at the origin of the truck FA in FA components. JACKAX 1 to 6

- the six motion base actuator accelerations. JACKL 1 to 6

- the six motion base actuator extensions. PHI SIM, THETA SIM, PSI SIM

- the simulator F

S Euler angles (roll, pitch and yawl

PS SIM, QS SIM, RS SIM

- the simulator angular velocity in FS components. PSI TRK

- the truck FA yaw Euler angle. RS TRK

- the truck yaw angular velocity about the FA z-axis. SFX ERR, SFY ERR, SFZ ERR

- the specific force sensation error (eg. [SFX SIM] - [SFX TRK])

SFX SIM, SFY SIM, SFZ SIM

- the sensed specific force at the simulator driverls head in Fps components,

SFX TRK, SFY TRK, SFZ TRK

- the sensed specific force at the truck driverls head in FPa components.

SP ERR, SQ ERR, SR ERR

- the angular velocity sensation error (eg. [SP SIM] - [SP TRUCK])

SP SIM, SQ SIM, SR SIM

- the sensed angular velocity at the simulator driverls head in Fps components.

SP TRUCK, SQ TRUCK, SR TRUCK

- the sensed angular velocity at the truck driverls head in FPa components.

VXBB TRK, VYBB TRK

the translational velocity of the truckls center of gravity in FA components.

VXSI SIM, VVSI SIM, VZSI SIM

- the translational velocity of the origin of the simulator F_S in F

I components. XSI, YSI, ZSI

YSI TRK

- the translational displacement of the origin of the simulator F_S in F_I components.

- the lateral translational displacement of the truckls center of gravity in F_I components.

,

Reference Frames, Superscripts and Subscripts

- a reference frame fixed to the truck and located at the same position relative to the cab as FS in the simulator

(see Figure 3.2)

- an inertial reference frame (see Figure 3.2) - either of the head-fixed reference frames

- the head-fixed reference frame for the truck driver (see Figures 2.1 and 3.2)

- the head-fixed reference frame for the simulator driver (see Figures 2.1 and 3.2)

a reference frame fixed to the simulator with its origin located at the centroid of the upper simulator frame bearing blocks (see Figures 3.2, 3.5 and 3.6)

( )x,( )Y,( )z _ the three components of a vector ( ).

-1-1. Introduction

Advanced flight simulators are currently used in a wide range of training, research, development and accident investigation applications by the aerospace community. Only rather rudimentary simulators have been applied to the same tasks in the ground vehicle area, largely due to the high costs involved. However at the present time several advanced driving simulators are under development in Europe, approaching in

complexity that of the flight simulator.

Recent funding from NSERC and the Ontario Government and support from Air Canada and CAE Electronics has enabled UTIAS to develop an advanced simulator facility for both flight and ground vehicle studies. The present investigation is intended to demonstrate the capabilities of the facility's motion base to simulate the motion environment experienced by a truck driver during typical highway maneuvering. This represents the first step in the development of a unique Canadian facility capable of a wide range of driver/vehicle study applications.

The simulator motion is measured by an on-board sensor package consisting of three linear accelerometers and three rate gyros. A vestibular model representing the driverls motion sensing organs is employed to predict the sensation of motion produced by the measured simulator motions. The motion commands for these tests are generated by an MTC program which simulates the response of a truck to control inputs from a driver. The quality of motion is judged by comparing the predicted motion sensations in the simulator with those predicted in the truck.

Because of the limited travel of most fixed-base simulators it is necessary to modify the outputs from the vehicle simulation program before applying them to the motion base controller. This process

applies a combination of scaling, limiting and high-pass filtering in order to reduce the amplitude of the vehicle motion variables and to remove the low frequency acceleration components which tend to lead to large simulator displacements. In carrying out these steps care must be taken to minimize their adverse impact on the similator driver's sensation of motion. One special effect which is commonly employed to restore some degree of the sensation of low-frequency translational acceleration (such as side force during a steady turn) is cal led tilt-coordination. In this process the simulator is slowly rotated to a modest tilt angle, which is then sustained to create the illusion of modest steady-state acceleration. When combined with a good visual display scene this is quite effective.

The current study is preliminary in nature. Because the simulator is not yet complete it was not feasible to carry out tests with human subjects. The aim was to generate the necessary software for generating simulator motions suited to ground vehicle studies, to select a good set of system parameters, and to analytically evaluate the resulting simulator performance for a few truck maneuvers.

2. Vestibu1ar Mode1s

In order to predict the qua1ity of the motion cues produced by

the simulator it is necessary to deve10p mathematica1 mode1s of the human vestibu1ar system. A1though many sensors distributed throughout the body p1ay a ro1e in the detection of motion it is apparent that the vestibular system located in the head provides the dominant signa1s (2.1). Models of the vestibu1ar system have been deve10ped and

several are reported in the review paper listed as Reference 2.2. From the data presented it can be seen that the model representing the

response to rotationa1 motion is much better documented than that for trans1ational motion. The fo11owing mode1s, although they do not represent all aspects of motion sensation, are considered to be

reasonably good engineering approximations to the primary sensations. 2.1 Rotational Motion Sensation

The primary sensing organs for rotationa1 motion are the semi-circu1ar cana1s located in the head as shown in Figures 2.1 and 2.2.

It has been demonstrated that this system acts as an angu1ar velocity sensor and in the present models three orthogonal sensing axes are used to represent the sensation. The model is presented in Figure

2.3 and each of the three channels has the same form. The corresponding transfer function is

-,.. w (2.1) w

where w is the angular velocity input about any one of the three axes

A

and w is the sensation of angu1ar velocity.

The differential equation corresponding to Equation 2.1 can be written as

.

x

=

A x + B w (2.2)

where A

=

_{-a 2} 0 (2.4) -al 0 1 -aa 0 0 B

=

_{[b 2} 0 DJ T - (2.5) aD

=

(T_LT

_s

T_a)-l (2.6) al

=

(T_LT_s)-l + (T_aT_L)-l +

(TaT~)-l

(2.7) a ₂

=

T -1 _L + T -1 S + T -1 _a (2.8) b ₂

=

T -1 _S (2.9)

The model parameter values are contained in Tab1e 2.1. The frequency response for the yaw channel is plotted in Figure 2.3. From this it can be seen that the system is a good sensor of angular velocity in the

"

frequency band 0.2 rls to 10 rls. lts response w tends to zero for both steady-state angular velocity and steady-state angular acce1eration inputs.

2.2 Specific Force Sensation

The otolith is the other major sensor contained vlithin the vestibular system. It senses specific force f defined as the vector _-r difference between translational inertial acceleration and the

acceleration due to gravity, that is

f

=

a - a

-r - r ~

(2.10) The active portion of the otolith system in man is contained within

rj..

the utric1e, the common base of the semicircu1ar cana1s. The response of the oto1iths is combined with that from other body sensors to

,..

genera te the perceived specific force f with components a10ng the

- r

three head axes of Figure 2.1. In the present study the subjective sensation model of Meiry and Young summarized in Reference 2.2 is emp1oyed.

The model is presented in Figure 2.4 and each of the three channe1s has the same form. The corresponding transfer function is given by

-f _

K(TbS + 1)

f - (TLs + 1)(Tss + 1)

(2.11)

where f is the specific force a10ng any one of the three axes. The differentia1 equation corresponding to Equation 2.11 can be written as

x

=

A x + Bf

"

f - x _{- 1} where A

=

[-al

:]

-aa B

=

_{[ b1} ba] T a ₀

=

(T LTS)-l a ₁

=

T -1 _L + T -1 _S b ₀

=

K(T LTS)-l b ₁

=

KT_b(T_LT

_s

)-l (2.12) (2.13) (2.14) (2.15) (2.16) (2.17) (2.18) (2.19) The model parameter va1ues are contained in Tab1e 2.2. The frequency

response for the heave channe1 is p10tted in Figure 2.4. From this it can be seen that the system is a good sensor of specific force in the frequency band 0.2 rls to 2 rls. It has a steady response to

constant values of f. Because this system will respond to the gravity vector alone when the translational inertial acceleration of the head is zero, it can be used to determine one's tilt orientation with respect to the local vertical.

3. 3.1

Simulator Facility Motion Base Hardware

The UTIAS Flight Research Simulator is pictured in Figure 3.1. It has a six degrees-of-freedom motion base with the performance specifications listed in Table 3.1. The system is operated by a PE 3250 digital computer. The six hydraulic actuators employ hydro-statie bearings and thus produce a very smooth response. The system is typical of current technology flight simulators.

3.2 Motion Sensing Package

The translational and rotational response of the simulator was measured by a motion sensing package consisting of three orthogonally

mounted line~r accelerometers (sensing specific force f) and three

-r

orthogonally mounted rate gyros (sensing angula~ velocity 00). The

...

instrumentation specifications are presented in Tables 3.2 to 3.7. The sensor outputs were first passed through low-pass filters and then recorded by the PE 3250 computer. The sampling rate of the analog-to-digital converters was set at 20 Hz and they have a 12 bit resolution. The low-pass filters had a 30 Hz break frequency and served to remove any high frequency noise from the signals. The sensor package was

mounted on the floor of the cab with its axis system aligned with F

_S

(see Figure 3.2). The value of specific force at alocation Q

separated from the sensor package accelerometer by the position vector

EQ

is found by using

where

!.os

=

is

+ .§. ~S

!.os

_{represents the FS components of the}

specific force at the point Q

is

represents the F_S components of the specific force at the accelerometer location

Bos

are the components of ~ _{in FS}

G

=

~ss

=

3.3 Simulator Motion Base Drive Algorithm

(3.2)

In developing the equations for the washout filters it is assumed that the simulation task is that of creating at the driver's location in the simulator a specific force vector and an angular velocity vector approximating those that the driver would experience in an actual

vehicle. That is

(3.3)

(3.4) The relevant axis systems are shown in Figure 3.2.

The simulator motion is specified with respect to reference frame FS. In order to minimize the motion base actuator extensions associated with the tilt-coordination process the origin of FS is located at the centroid of the upper frame bearing attachment points. The correspond-ing reference frame in the vehicle is FA. Because the vehicle and the simulator are assumed to be rigid it follows that Equations 3.3 and 3.4 can be replaced by

...

iss

~ iAA (3.5)

(3.6)

The values of ~ and ~A come from the vehicle equations of Section 4.

~ and ~ are the inputs to the washout algorithm. They are scaled, limited and filtered in order to restriet the motion base travel to remain within the physical system constraints.

3.3.1 Translational Motion Channel

As shown in Figure 3.3 iAA is first passed through the sealing and limiting block represented by HP SCALE. The output is given by

fl Y

=

LIM (K fY )

Y Y AA

(3.7)

(3.8)

(3.9)

where the Ki are fixed sealing factors and LIMi(x) limits the magnitude of the argument x to be less than a specified value xL1M.fl is taken to represent the desired specific force components for the simulator reference point (i.e. the origin of F_S) expressed in F_S components.

From Equation 2.10 this can be transformed into the desired translational inertial acceleration of the simulator reference point expressed in

F_S components by forming

~

=

il

+ 5l.S (3.10)

The corresponding inertial frame F

1 components are given by

(3.11)

sin~ssin6Scos~S -co~ssin~s sin~Ssin6Ssin~S +cos~scos~s sin~SCOS6S cos~ssin6Scos~S +sin~ssin~s cos~Ssin6Ssin~S (~.12) -sin~scos~s COS~SCOS6S

Note that instead of adding ~S upstream of the ~IS b10ck in Figure 3.3

an equivalent and simp1er form cou1d be achieved by adding ~I immediate1y

fol1owing the bloek. In either case the same a2 is generated. The high-pass filtering is app1ied to a2 by the HP FILT block and the resu1t

is cal led ~SI and this is the commanded simulator trans1ationa1

inertia1 acce1eration in F_I components. It is used to ca1culate the

motion base actuator lengths as described in Section 3.3.3. 3.3.2 Rotational Motion Channe1

As shown in Figure 3.4 there are two components that go into

generating the simulator Eu1er ang1es !S. The component SSH comes from

high-pass filtering ~ and is intended to simu1ate the rotationa1

velocity of the vehiele. The second component SSL comes from a ti1t-coordination a1gorithm and is intended to tilt the simulator in order to simulate sustained specific force cues. Thus

~S

=

SSL + SSH (3.13)

Both processes are described below.

3.3.2.1 Simu1ation of Vehic1e Rotationa1 Velocity

~A is passed through the sealing and 1imiting b10ck represented

by HP SCALE in Figure 3.4. This process has the same features out1ined in Section 3.3.1 for the trans1ationa1 channe1 HP SCALE b10ck. The output from this proeess is wl and fo110wing Equation 3.6 it is taken

\

~

..

to represent the desired simulator rotationa1 velocity written in FS components. Because the motion base actuator 1ength computation requires the simulator Eu1er ang1es, the Eu1er ang1e rates corresponding to

wl are computed for the simulator reference frame FS from

.

g

=

Is

~ (3.14) where

Is

=

1 siMstanss _cos</>stanss

o

-sin</>s (3.15)

o

•

The high-pass filtering is app1ied to

g

by the HP FILT b10ck and the resu1t is integrated to produce SSH, the high frequency component of ~S. 3.3.2.2 Ti1t-Coordination

Sustained trans1ationa1 inertia1 acce1eration is sensed by the driver as a long-term change in the magnitude and direction of the specific force in the absence of rotationa1 motion. This cannot in general be simu1ated by trans1ationa1 motion due to the motion base travel 1imits. However it is possib1e to alter the direction of the specific force experienced by the driver in the simulator by ti1ting the cab. It has become common practice in f1ight simulators to emp10y cab tilt to simu1ate the effect of sustained trans1ationa1 inertia1 acce1eration.

The simulator Eu1er ang1es for ti1t-cordination (SSL) are computed under the assumption that all other simulator motion and displacements are absent. In this process the time rate-of-change of SSL is 1imited so that its contribution to the rotationa1 motion of the simulator is be10w the driverls thresho1d for the detection of angu1ar. velocity. The

portion of Figure 3.4. It is passed through the sca1ing and 1imiting b10ck represented by LP SCALE. Because of the form adopted for the ti1t-coordination a1gorithm it is on1y necessary to app1y the LP SCALE

process to the x and y components of ~A. Thus

(3.16) f2Y

=

LIM (K fY )

Y Y AA (3.17)

(3.18) where LIMi(x) is described in Section 3.3.1. f2 is then processed by a low-pass filter represented by the b10ck LP FILT in Figure 3.4 to produce fL, the low frequency specific force to be simu1ated by ti1t-coordination. fL represents components in FS• The ti1t-coordinationprocess rotates the simulator cab unti1 the vector represented by fL is a1igned with the negative gravity vector -go This ensures that the low frequency

specific force at the simulator driverls location has the correct orientation re1ative to his reference frame Fps • lts magnitude wi11 of course a1ways be 9 in this case. It can be shown that this ti1t-coordination is obtained by generating two simulator Eu1er ang1es in pitch. and ro 11 eSL

=

-tan-l{(fLx/fLz)coS~SL} ~SL

=

tan-1(fLY/fL z ) ljiSL

=

0 (3.19) (3.20) (3.21)

In the case of modest ~ levels it fo11ows that a good approximation can be obtained to Equations 3.19 to 3.21 with eSL represented by

eSL

=

fLx/g ~SL

=

-fLY/g 1jJSL

=

0 (3.22) (3.23) (3.24) \

..

This simp1ified formu1ation has been used in the present study. 3.3.3 Actuator Length Ca1cu1ations

The geometrica1 structure of the six degrees-of-freedom synergistic motion base is shown in Figure 3.5. The relevant vectors re1ating the 10cations of the upper and 10wer bearings of the i th actuator are

given in Figure 3.6. rt can be seen that the 10cation of the cab frame FS with respect to the inertia1 frame Fr is given by

(3.25) Thus the actuator 1ength vector can be found from

li

=

Ai + S - Bi

"7 ""?' ""?' ""?' (3.26) Expressed in Fr components Equation 3.26 becomes

lor

=

_{Ao r} + SI - Bo_r

-1 -1 - -1

(3.27)

=

!:.r0.is

+ ~I - ~iI

where ~iS and ~ir are geometrica1 constants and ~r is found from the outputs of the washout filter a1gorithm by using

t t 2

~r = ~r(O)

+

IJ

~SIdt

(3.28)

o 0

~r(O) is se1ected so as to start the simulator from a desired location.

The actuator command signa1 emp10yed for the i th actuator is

lo

= (l~rlor)~-L

1 -1-1 (3.29)

where L is usua11y the 1ength of the actuator when the simulator is at its neutral position (i.e. with all the actuators extended to one half their stroke).

The motion base controller a1so requires va1ues of li in the present

.. ..

through a finite difference a1gorithm. The li and liest b10cks are located in Figure 3.3 as the fina1 stages of the a1gorithm. The

geometrica1 data for the UTIAS F1ight Research Simulator are contained in Tab1e 3.8.

4. Motion Base Test Runs

The initia1 washout filter eva1uation was performed on a Perkin E1mer 3250 digita1 computer. The truck motions resu1ting from two

different steering and braking maneuvers were generated using a simu1ation

program provided by MTC (hereafter, called MTCSIM). These motions were

then fed to the filter eva1uation program TRUCK described herein. Washout filter characteristics were adjusted to obtain the best reproduction of simulator truck driver sensations within the constraint of a110wable motion base actuator extensions.

Once the washout filters had been chosen, the resu1tant actuator time histories were app1ied to the simulator whi1e the motion sensing

package recorded the simulator motion. Final1y, the simulator truck driverls motion sensation in response to these recorded motions was eva1uated and compared to the truck driveris.

4.1 Simu1ated Maneuvers

The tractor/semitrai1er truck configuration chosen for all these tests is given in the sample input data in Figure 16 of Reference 4.1. The

current implementation of the MTCSIM program was va1idated by dup1icating the resu1ts given in that examp1e and the steering and braking inputs were then changed as desired. No jackknife control devices were used.

Two different truck maneuvers were se1ected for the washout filter selection process.

1. Double Lane Change - The truck is steered at constant speed (43 km/h) from the left 1ane into the 1ane on its right and is then returned to its original 1ane. The vehic1e moves a maximum of 3.66m laterally. The ful1 maneuver takes 7 seconds and the steering and braking inputs are shown in Figure 4.1. The steering ang1e refers to the front road whee1s and the braking force is the attempted brake force at each whee1. Tota1 simu1ation time is 15s.

2. Braking and Entry into a Constant Rate Turn - The truck is braked* from an initia1 speed of 80 km/h to 40 km/ho At approximate1y 54 km/h, a turn entry is initiated with constant1y increasing steering ang1e unti1 the steering ang1e that wi11 produce a turn radius of 87m is reached. This steering ang1e remains constant unti1 a tota1 simu1ation time of 15s is reached. The steering and braking inputs for this maneuver are shown in Figure 4.2.

4.2 Modifications To MTCSIM

The MTCSIM program used to generate the truck motions during a

simu1ated maneuver was identica1 to the program received from MTC (described in Reference 4.1) except for the fo11owing changes:

1. Array sizes were changed to a110w runs with up to 800 output points (instead of the previous 100).

2. Two new variables were made avai1able for output. a~ (variab1e #86),

the driverls head longitudina1 inertial acceleration in body axes

and a~ (variab1e #87), the corresponding lateral inertial acce1eration.

In order to ca1culate these variables, it was assumed that the driverls head was 30 cm behind the front tractor ax1e (Reference 4.2) and -85% of the ha1f-latera1 distance between the front tires to the 1eft of the center1ine of the vehicle.

The program is run exact1y as outlined in Reference 4.1 but if the filter eva1uation program is to be used, the file output option must be

se1ected and output variables #7 (~), 18 (~), 86 (a~) and 87. (a~) must

be inc1uded.

4.3 Program TRUCK 4.3.1 Function

Program TRUCK was deve10ped to eva1uate the washout filters. Given * Using equa1 brake pressure on all whee1s.

«

-17-the truck driverls head motion calculated in -17-the MTCSIM program, TRUCK will genera te the corresponding simulator motion and compare the

vestibular sensations in the truck and simulator. The jack extensions required to achieve the simulator motion are also calculated. Plots are generated as specified by the user. The output variable choice includes all those in the MTCSIM output file, as well as all the motion and

sensation variables calculated in TRUCK. The user may optionally store the results in an output file so that the calculated jack extensions can be later used to drive the simulator.

4.3.2 Method

The flowchart for the TRUCK program is shown in Figure 4.3 and

includes the following steps (the step numbers correspond to those included in comment statements in the program listings given in the Appendix):

1. Data is read from the MTCSIM output file and stored.

2. The time step is checked to ensure that a step of 0.05 s was used. If not, the program is stopped.

3. Data is checked to ensure it contains the essential variables: .. x y

~A' ~A' apA' apA' If not, the program is stopped.

4. Subroutine ADJUST linearly interpolates the data to ensure an exact time step of 0.05 s (since the MTCSIM output step varies somewhat).

• . • ;. x y

5.

f

_{PA '} ~A' ~A and iAA are generated uSlng ~A' ~A' apA' apA'

6. ipA and ~A are used to obtain the vestibular response of the truck

1\ A

driver (!PA, ~PA)' The differential equations of the vestibular model given in Section 2 (coded in subroutines VESTIB, FeNl and INTERP), are integrated using the IMSL routine DGEAR.

7. iAA and ~A are used as inputs to the equations which represent the washout filters, thereby yielding the simulator motion aSI ' ~I' ~I'

Is'

~SS' ~SS' Subroutines MTCWSH, VMULT and LIBS are used.

.

8. The hydrau1ic jack motions (f_{i , ti'} f_{i ) are ca1cu1ated from} ~I and .ê.s using subroutines JACKDRVR and VMULT.

9. Simulator motion (!SI' ~S) _{is transformed to body axes FS} (~PS' ~S) using subroutines VTRANSP and VMULT. Note.that ~ _{gives the 10cation of Fp} with respect to FS'

10. The gravity vector in bOdy axes is subtracted to obtain

i

_{ps '} the specific force at the simulator driverls head.

11.

i

_ps and ~SS are used to obtain the vestibu1ar response of the

J\, 1\

simulator driver (!PS' ~PS) as in (6) above.

12. Resu1ts from (6) and (11) are compared to obtain the vestibu1ar errors e_f" and e".

- p ~

13. Subroutine OUTP is called to plot andjor output on file all the required variables •

4.3.3 Inputs and Outputs

To run th~ TRUCK program, the user must assign the MTCSIM output file to the read 10gica1 unit (present1y IR=3), and ensure that the proper time step and variables are inc1uded. The program wi11 give diagnostic messages if these requirements are not fu1fi11ed.

Af ter all ca1cu1ations are performed, the user is asked to select the required plot variables from the fo110wing:

1. All the variables found on the MTCSIM output file.

2. FXAA TRK, FYAA TRK, FZAA TRK; The specific forces at the truck centroid (the origin of FA) in FA components.

3. SFX TRK, SFY TRK, SFZ TRK; The sensed specific forces at the truck driverls head in Fpa components.

4. SP TRUCK, SQ TRUCK, SR TRUCK; The sensed angu1ar rates at the truck driverls head in Fpa components.

5. AXSI SIM, AYSI SIM, AZSI SIM; The simulator centroid acce1erations.

6. VXSI SIM, VYSI SIM, VZSI SIM; The simulator centroid ve10cities in F_I components.

7. XSI SIM, YSI SIM, ZSI SIM; The simulator centroid position in FI components.

8. PHI SIM, THETA SIM, PSI SIM; The simulator Eu1er ang1es.

9. PS SIM, QS SIM, RS SIM; The simulator angu1ar rates in F_S components. 10. SFX SIM, SFY SIM, SFZ SIM; The sensed specific forces at the

simulator driverls head in F_ps components.

11. SP SIM, SQ SIM, SR SIM; The sensed angu1ar rates in the simulator in Fps components.

12. SFX ERR, SFY ERR, SFZ ERR; The error in specific force sensation. 13. SP ERR, SQ ERR, SR ERR; The error in angu1ar rate sensation. 14. JACKL 1 to 6; The six motion base actuator positions.

15. JACKAX 1 to 6; The six motion base actuator acce1erations.

Any variab1e may be p10tted against any other. The user must enter the number of plots to be output in 12 format, and the abcissa and ordinate variables for each plot in 212 format. As atime-saving measure, if 99 is entered as the required number of plots, all variables wi11 be

p10tted as a function of time; and if 98 is entered, all the simulator motion and sensation variables wi1l be plotted versus time.

Once the plots are completed, the user may select whether or not the actuator positions and accelerations shou1d be stored on file. If they are, these time histories can later be used to drive the simulator motion base.

4.4 Washout Filter Selection and Trial Run Resu1ts

Since the unmodified truck motions required in both test maneuvers were beyond the capacities of the UTIAS simulator, washout filters were _,

inc1uded to reduce these motions to within the simulator 1imits*. Usua11y washout filters are general in nature and wou1d therefore be a compromise solution to handle all possib1e truck motions. In the present case, how-ever, in order to demonstrate the ful1 capabi1ities of the simulator,

the washout filters were matched to the individua1 maneuvers. This resulted in two fina1 washout filter sets, one for the double lane change, and one for the braking and turn entry maneuver. The fo11owing describes the fina1 form of these filters, as we11 as some of the interim steps in their

design.

4.4.1 Double Lane Change Washout Filters

The truck motions invo1ved in the double 1ane change maneuver are shown in Figure 4.5. The vehic1e simu1ation assumed that ro11, pitch and heave were absent and thus these variables do not appear in the plots.

In comparison to the simulator motion capabi1ities these truck motions are of high amplitude. It was therefore expected that the high amplitudes

wou1d have to be sca1ed down or fi1tered and that the low frequency trans1ationa1 acce1erations wou1d best be simu1ated with ti1t-coordination.

Initia1 computer eva1uation started with no washout filters, i.e., simulator motion identical to truck motion. The resu1tant motions all exceeded the simulator capabi1ities. The first attempts to reduce these centered on obtaining the best possib1e response with no ti1t-coordination. The truck yaw motion (PSI) was fed through unsca1ed and unfi1tered since it was modest (±9 deg. peaks) and the yaw simu1ation was therefore perfect. The other principa1 motion component which had to be simulated was the

lateral specific force. Due to the modest amount of lateral travel avai1ab1e, the best simulation was obtained with 1imiting in the body axes and

first order filtering of lateral acce1eration in the inertia1 frame. * The UTIAS simulator actuators are caDab1e of ±0.46m extension and this

was the primary 1 imitation on possible mottons (velocity and acce1eration 1imits were not approached). As we11, the simulator control hardware starts a shutdown procedure at 0.88 of fu11 extension and ±0.40m was therefore used as the travel limit.

The components which make up the washout filters without tilt-coordination for this maneuver are shown in Figures 3.3 and 3.4 and detailed in Table 4.1 under the heading DLC #1. The resulting predicted simulator motions and simulator pilot sensations from TRUCK are shown in Figure 4.6 It should be noted that the rotational motion is identical to that in the truck (no pitch or roll; some yaw). There is some error in specific force sensation in the x-axis, but this is modest and unlikely to be noticed relative to the y-component error. The y-component error is large due to the limited simulator travel • Only the initial changes in acceleration can be simulated while sustained accelerations are ignored. This can be remedied to some extent by introducing tilt-coordination.

It should also be noted that due to the low order of the filters, there are steady-state x and y position offsets in the simulator even af ter completion of the maneuver. This was considered acceptable for the

present case, but would not be allowable in a more general on-line filter. Tilt-coordination between y-specific force and roll angle was then introduced to help simulate the lateral force sensation. Af ter some further iterations, filters DLC #2 outlined in Table 4.1 and Figures 3.3 and 3.4 were chosen as the best compromise for this maneuver. These filters allow a small amount of lateral translational motion in the simulator to represent the initial cue, and then rely on roll tilt-coordination to supply the more sustained part of the cue. The x and z

simulator inertial acceleration components are set to zero, as is the simulator pitch angle. The yaw angle is again fed straight through, yielding perfect simulation in that degree of freedom. The resulting predicted simulator motions and pilot sensations from TRUCK are shown in Figure 4.7. When compared to Figure 4.6, this simulation is seen to give an improved shape for lateral specific force sensation, reaching

the appropriate magnitudes. The main source of error in that degree of freedom is due to a time lag introduced by the slow buildup to the proper roll tilt-coordination angle. Increasing the allowable tilt rate would reduce this lag, but increase the error in roll sensation. Since the sensation threshold is about 3 deg/s, the present tilt rate limit of 5.8 deg/s will be sensed by the simulator driver and increasing this could be detrimental. It is expected that some of this spurious ro11 cue would be suppressed by the visua1 display in the actual simulator remaining

horizontal , and any perceived roll angle would be interpreted as suspension travel (not modeled in this simu1ation) which is fortuitous1y in the same direction. Summarizing this run, we have:

1. 10ngitudina1 and vertical specific force and pitch velocity very close to or below sensation thresholds. These wi11 go unnoticed relative to the other motion cues,

2. lateral specific force of the right shape and magnitude, but with some lag (see SFY in Figures 4.5 and 4.7),

3. perfect yaw simulation,

4. some roll motion detected but hopefu11y attributed to other sources by the driver.

4.4.2 Braking and Constant Rate Turn Washout Filters

As in Section 4.4.1, it was found that the truck motions for this maneuver, shown in Figure 4.8, were of much 1arger amplitudes than could be duplicated on the UTIAS simulator. Tilt-coordination was again

necessary to simu1ate the sustained 10ngitudina1 and lateral specific forces invo1ved. A number of runs were performed with different filter orders and parameters, and the fina1 compromise arrived at is shown in Table 4.1 under the heading B+CRT. The predicted simulator motion and

vestibular responses in the truck and simulator are compared, the follow-ing should be noted:

1. The yaw sensation has a good onset cue, but the sustained yaw rate cannot be simulated.

2. The changes in vertical specific force will probably not be detectable.

3. Pitch and roll sensations due to tilt-coordination will, once again be somewhat above threshold, but may be suppressed by the visual cues and/or attributed to suspension travel.

4. Longitudinal and lateral specific force are of the proper shape and magnitude but have a small lag due to tilt rate limiting at 5.8 deg/s. 4.4.3 Trial Runs on the UT lAS Simulator Facility

The jack lengths and accelerations obtained with the final versions of the washout filters (DLC #2 for the double lane change shown in Fig. 4.7, and B + CRT for the braking and constant rate turn maneuver shown in Fig. 4.9) were used to drive the motion base of the UTIAS simulator facility while the motion sensing package (described ln Section 3.2) recorded motions in all six degrees of freedom. This was done in order to establish the fidelity of motion attainable for these two simulator maneuvers and to verify that the predicted vestibular response of the simulator driver would be close to that calculated in the two previous sections where the simulator dynamics were not included.

The motion sensing package was located near the centroid (the origin of F_S)' and its accelerometer outputs were corrected to yield the inertial accelerations and specific forces at the centroid and at the driver's head. The rate gyro outputs are shown directly and are valid at any point in the simulator. The calculated specific forces at the driver's head and the angular velocities were used as input to

thevestibular model described in Section 2 in order to estimate the actual simulator driverls vestibular response.

Figure 4.10 shows the motion and vestibular sensations obtained from the experimental data for the double lane change maneuver, and can be compared to Figure 4.7 which shows the commanded motions and to Figure 4.5 which shows the truck motions. Points to note in these figures are:

1. The inertial translational accelerations, ~SI' are close to those commanded, with some low amplitude, high frequency noise superimposed. This noise is presumably due to hydraulic system vibrations transmitted through the structure of the simulator, and possibly from electronic noise in the signals.

2. The angular rates and positions are close to those commanded. Some of the simulator dynamics can be seen in the overshoots present in the plots of PSS' rSS , qss and ~S' as well as in the distorted peaks of the PSS curve.

3. The vestibular sensation plots for the commanded and actual motions are very similar and it can be assumed that, except for the distorted roll rate peaks, the simulator dynamics can be neglected when designing washout filters for this type of maneuver. The two most important cues, the yaw sensation and lateral specific force sensation, are almost identical to those commanded, demonstrating a high degree of fidelity in this simulation

Figure 4.11 shows the measured motion and estimated vestibular sensations for the braking and constant rate turn maneuver, and these can be compared to the equivalent commands shown in Figure 4.9. This experimental data shows many of the same trends as the previous set, with some overshoot, and some distortion of the PSS and qss peaks. The vestibular sensations are very close to those commanded and the fidelity

of the simu1ation is, once again, considered very good as can be seen by comparing the vestibu1ar response estimates of Figures 4.8 and 4.11.

-26-5. Summary

1. The MTC truck simulation program MTCSIM has been slightly modified and implemented on the UTIAS PE 3250 computer.

2. A software package (TRUCK) has been developed to generate simulator motion drive signals based on the outputs from MTCSIM and to predict driver vestibular motion sensations.

3. Washout filters for the UTIAS simulator facility have been designed for two driving maneuvers; a double lane change and a braking maneuver followed by a constant rate turn.

4. Test runs have been carried out for these two maneuvers in order to predict the truck response and the simulator response.

5. An experimental measurement program was carried out in the UTIAS simulator facility to measure the translational acceleration and rotational velocity generated by the motion base for the two test maneuvers.

6. The test results obtained in the simulator indicated that an excellent simulation of the mot ion cues associated with the two test maneuvers was achieved.

7. Based on the results of the present study it is concluded that the UTIAS simulator facility could be developed into a useful truck

2.1 Gum, D. R., IIMode1ing of the Human Force and Motion-Sensing Mechanism,1I

AFHRL-TR-72-54, June 1973.

2.2 Zacharias, G. L., IIMotion Cue Mode1s For Pi1ot-Vehic1e Ana1ysis,1I AMRL-TR-78-2, May 1978.

4.1 Bil1 ing, A. M., IISimu1ation of Jackknife Control Devices, 11 Ontario

Ministry of Transportation and Communications, CVOS-TR-78-04, May 1978.

4.2 Reid, L.O., Graf, W. O. and Billing, A. M., IIThe Obstac1e Avoidance

Maneuvre as Performed in a TractorjSemitrai1er Truck,1I Ontario Ministry of Transportation and Communications, TVS-CV-82-108, June 1982.

Rotation Motion Sensation Model Parameters (from Reference 2.2)

..;

Pitch _Ro" Yaw

(about y-axis) (about x-axis) (about z-axis)

\ (s) 5.3 6.1 10.2

TS(s) 0.1 0.1 0.1

T (s) _a 30 30 30

Table 2.2

Specific Force Sensation Model Parameters (from Reference 2.2)

Surge Sway Heave

(along x-axis) (along y-axis) (along z-axis)

TL(s) 5.33 5.33 5.33

TS(s) 0.66 0.66 _0.66

Tb (s) 13.2 13.2 _13.2

Motion Base Performance

AXIS MODE MAXIMUM EXCURSION

X LONGITUDINAL 68 in (1. 72m)

Y LATERAL 57.7 in (1 .49m)

Z VERTICAL 46.7 in (1. 19m)

P ROLL ±280 ₁₅1

Q PITCH 280 Ol nose up 340 lOl

nose down

R YAW ±300 121

AXIS MODE MAXIMUM ACCELERATION

X LONGITUDINAL + 0.7g, -0.9g Y LATERAL ±0.8g Z VERTICAL ±1.5g P ROLL ±475 deg/sec2 Q PITCH ±475 deg/sec 2 R YAW ±375 deg/sec2 ~

Sundstrand Model 303B Accelerometer Specifications

Range poss i b 1 e Voltage sensitivity Output vo 1 tage Noise

Supply Voltage and current

L inearity

Hysteresis and repeatability

= ± O.Sg to ± 40g = 10 V/g to 0.1 V/g adjustable

=

to ± S Volts = Below 1 MHz 1 mV rms = DC to 1 Hz S micro-g (resolution) :;: +28 VDC ± 10%; 40 mA '(max)

= ± O.OS% full scale = O.OOOSg

Output at 0 g = ± SO mg . (max) Zero shift with line voltage = O.OOS g/V (max) Sensitivity shift with line voltage = O.OS%/V (max) Operating temperature range = -6SoF to +18SoF Zero shift with temperature variation= O.Ol%/Fo

Transverse acceleration

Acceleration limit (any axis)

=

DC to S Hz ± 50g

= 5 Hz to 2 KHz 20g peak = lOOg

X Accelerometer Calibrations (Set No. 901)

Factory Recent Calibration

l. Range (g) ± 2g

2. Force coil current sensitivity

(mA/g) 0.2406

3. Maximum transverse sensitivity

(mg/g) <1

4. Zero 9 output (volts DC) -.003 .007

(mg) -1.2

5. Temperature null shift

(mg/100OF) -30

6. Line variation null shift

(mg/vo lt DC) <1

7. -1 9 output{volts DC) -2.500 -2.499

8. +1 9 output wolts DC) 2.494 +2.513

9. Voltage sensitivity

Y Accelerometer Calibrations (Set No. 902)

Factory Recent Calibration

l. Range (g) ± 2

2. Force coi 1 current sensitivity

(mA/g) .2406

3. Maximum transverse sensitivity

(mg/g) <1

4. Zero 9 output (volts DC) +.006 .109

(mg) 2.4

5. Temperature null shift

(mg/lOO°F) 5

6. Line variation null shift

(mg/volt DC) <1 7. -1 9 output (volts DC) -2.494 -2.407 8. +1 9 output (volts DC) 2.502 2.625 9. Voltage sensitivity (volts/g) 2.500 2.516

.

'

Z Acce1erometer Ca1ibrations (Set No. 201)

Factory Recent Ca1ibrations

i

1. Range (g) ± 5

2. Force coi1 current sensitivity

(mA/g) 0.601

3. Maximum transverse sensitivity

(mg/g) 1.5

4. Zero 9 output (volts DC) -.066 -.083

(mg) -66 - 67

5. Temperature nu11 shift

(mg/100°F) Ni 1

6. Line variation nu11 shift

(mg/vo1t DC) <1

7. -1 9 output (volts DC) -1.0688 -1.3204

8. ±1 9 output (volts DC) 0.9362 1 . 1550

9. Voltage sensitivity

1.

2.

Honeywell G6 440 Gnat Gyro Specifications

Mechanical:

Maximum input rate

=

± 120o/sec

Undamped natural frequency

=

35 Hz min

Damping ratio

= 0.416 at 140

0F

E1ectrica1 Pick-Off: (through demodulator) Output voltage Demodulator excitation

=

± 10 volts

=

± 15 volts 3. E1ectric Motor: Life Exci ta tion Starting power Running power 4. Uncertainty: Hysteresis Thresho1d Reso1ution Offset Linearity

Linear axis acce1eration sensitivity

Angu1ar axis acce1eration sensitivity

Cross axis acce1eration sensitivity

Input axis a1ignment Temperature range Maximum allowed acce1eration Vibration (10 to 2,000 Hz) Shock

= 1000 hours minimum

= 26 volts AC at 400 Hz, 2 phase

(single phase operation is accomplished with the use of a capacitor)

=

4.5 watts each gyro

= 3.5 watts each gyro

= 0.1% fu11 sca1e

=

O.01o/sec

= O.01o/sec

= O.l o/sec

=

± 0.25% to ± SOa/sec

=

± 2.0% to ± 100o/sec

= 0.05

0/sec/g

= 0.0006o/sec per o/sec 2

=

Ni1

=

to within 15 minutes of arc

=

-650_{F to +200oF}

= lOOg

=

20g

Rate Gyro Factory Calibrations

q, pitch p, Ro11 r, Yaw

(x 289) (x 645) (x 642)

Range ± 112 ± 113 ± 113

Scale Factor (mV/o/sec) 100.7 100.3 100.1

(lOl. 7) (101.4) (102.2)

Threshold (% F.S.) <.01% <.01% <.01%

Zero Offset (o/sec @ 140°F) .009 .079 .019

(.0606 ) (-.0056) (.0920)

Hysteresis (o/sec) .029 .049 .039

Acceleration sensitivity (o/sec/g) .038 .021 .016

Damping ratio (@ 140°F) .416 .416 .416

Natural frequency (Hz) 39.2 40.2 40.6

Geometrical Parameters of the UT lAS Flight Research Simulator (all values in m) AlS = [1.47 0.10 OJT ~2S = _{[1.47 -0.10 OJ}T A3S = _{[-0.65 -1.32 OJ}T ~S = _{[-0.82 -1.22 OJ}T A5S = _{[-0.82 1.22} O]T ~S = _{[-0.65 1.32 OJ}T ~1I = _{[1.22 1.52 OJ}T ~I = _{[1.22 -1.52 OJ}T ~I = _{[0.71 -1.82 OJ}T ~I = _{[-1 .93 -:0.29 OJ}T ~I = _{[-1 .93 0.29 OJ}T ~I = _{[0.71 1.82 OJ}T RSS = [0.87 0.44 -1. 72J T ~I(O) = _{[0 0 -1.84J T} L = _2.34

Configuration ot Wa5houtFilter5 BlOCK NO. FIG. 3.3 DlC #1 FIG. 3.4 1 Sealing of 1 If~I<0.5 m/5 2 2 Ineluded T - 5 3 F - K 5+4 4 K

=

1.5 on x ehanne 1 K

=

1.5 on y ehannel K

=

0.0 on z ehannel 5 Omitted DlC #2 Omitted Omitted 2 TF

=

K,s s2+.565+.04 K

=

0.00 on x ehannel K

=

0.21 on y ehannel K

=

0.00 on z ehannel TF

=

G 9.61 52+4.345+9.61 G

=

1 on ~ ehanne1 G

=

0 on

e

ehannel B+CRT Omitted Ineluded 2 TF = Ks ._5_ 52+25+.25 5+.5 K

=

0.5 on x ehannel K

=

0.5 on y ehannel K

=

0.0 on z ehannel TF

=

G 9.61 52+4.345+9.61 G

=

1 on ~ ehannel G

=

1 on e ehannel

6 Omitted Rate 1imiting of 5.8°/5 Rate limiting of 5.8°/5

7 Omitted Omitted

eSH=O

s TF

=

5+1.5

for pand q ehannels. TF

=

1.6S2 • 5

52+.085+.01 5+1.5 for r ehannel

y Loterol Axis Sog i ttal Axls Z Vertical Axis

Left Superior Left Horizontal Left Posterior X Right Horizontal

--f----_

Y (Right Side) Right Posterior

w

...

L

8 .

Tas

...

(TLs

+

l)rrss

+

1)

-

Tas

₊

1

-

W

CUPULA

WASHOUT

,....

01

~ EîîiîiIIII:

360

m

~

c

,....

_(!)

180

...-IJ.J IJ.J _C

c

-40

...-::l IJ.J

0

~

en

-

~

«

Cl.

J:

-180

:i

-80

Cl. ,

«

.

-360

0.1

I

10 100

_0.1

I

10 100

FREQUENCY

(rls)

_FREQUENCY

_(rls)

f

~I

---( TL

S

+

1 ) (TSs

+

1)

.. f

OTOLITH

..-.-

0,

~

,

360

al

-C _(!)

180

-

LLJ LLJ C

c

-40

-::::>

IJ.J

0

t=

Cf)

<t

..J :I:

-180

0-:E

-80

0-<t

.

-360

0.1

I

10 100

_0.1

_I

_{10 100}

FREQUENCY

(r /s )

_FREQUENCY

_{(r /s )}

Figure 2.4 Model of the Otolith

-

.

o

....

«

...J

:::>

~

-Cl)

) ( ) ( .ttiiiii--+--~ N ) ( N lil E <lJ +-' lil >. V) lil 'r-X c:x:: N

.

M <lJ s.. ::s Ol 'r-LL...

L

_[s

<D

., ®

j -

@ @ - - - j

"

HP

J00:

02

HP

OS! ~I

~

SCALE

₊

L

rsx

I'"

-

FILT

-

,. S2 I

1-

..

i.

..

,~ " I

--I

I

!A

i

.

I

L _________

J

...

ACCN

....

EST

~s

_liest

..

fA

LP

f2

LP

fL

-

TILT

~SL

~

...

gs

A

SCALE

~

.

FILT

,.

COORD

~s

A~

, - - - 7 - - - 1

.1

<V

I

HP

W1 {31

_HP

_{{3SH"+ {3}

sin

~

_SCALE

..

-

'!sx

~

,-

FILT

--

...

_s

I

90--:'

_COS

-

_LIS

WA LIS

I

_I

~

L - _________ J

Is

~

!s

~

!S

FIXED PLATFORM

PAYLOAD PLATFORM

s

_.,

x

y

Z

ATTACHMENT POINT PAYLOAD PLATFORM ATTACHMENT POINT FIXED PLATFORM

t:) UJ Cl UJ - l ₀ t:) 0 z _ei cr: a: UJ UJ ~ en ₀ 0 0 0 LIl t:) UJ Cl UJ ~ ₀ t:) 0 z _ei cr: a: UJ UJ ~ en 0 0 Ir. 0 Z UJ U ₀ a: 0 0 _ei LL UJ :s:: cr: a: CO 0 0 7.5 15.0 lf.o 7.5 15.0 TIME (S) _TIME (S)

Figure 4.1 Double Lane Change Maneuver Steering Input

7.5 15.0 TIME (S) o o ~....---. z UJ u N

I

\ a: 0 ... '---+-_ _ _ _ _ _ _ ~ o 0 LL UJ ~ cr: a: 0 co _o o LIl~ _ _ _ _ _ _ _ ~ _ _ _ _ _ _ _ ~ flI.o 7.5 TIME (S) 15.0

Step 4: N N Print diagnostic message Print diagnostic message

Call subroutine ADJUST to perform linear interpolation to obtain data exactly every

.05 s.

. x x

Step 5. Set _{f pA} apA

f - fY - aY

.:.pA - PA - PA

z

f_pA -g

iAA w_AA

Step 6:

Step 7:

Call subroutine VESTIB to integrate the 15 differential equations describing the yestibular models and thereby obtain

i

_{PA ,} ~A' (see Figure 4.4).

Call subroutine MTCWSH to wash out the truck motion into simulator motion and

~hereby obtain ~SI _{vSI '} ~I ' ~, ~SS'

w_{ss ' (see Figures} ~.3 and 3.4). .

~SI' ~SS' w ss

~I' .ê.s

Step 8: Call subroutine JACKDRVR to calculate jack extensions and accelerations from simulator position (SI) and Euler

angles (.ê.S).

-.e. i' ti' .e. i

Step 9: Set ~SS = ~SI ~SI

and _{apS-aSS-RS qss + rSS +RS pssqss-rss +RS PSSrSS+qss} x _ x x( 2 2) y( . ) z( . )

a~s=a~s+R~(Pssqss+rss)-R~(p~s+r~s)+R~(qssrss-pss)

z _ z x( . ) y( . ) z( 2 2) apS-aSS+RS pssrss-qss +RS qssrSS+PSS -RS PSS+qss ~s

"

C Figure 4.3 Continued

-

B ""

r

~S

Step 10: Set _{f pS} x

=

_apS x + gS1n8. s

f~S =

aY _{PS -gsincj>Scos8 S}

.z

f_pS

=

_{apS -gcoScj>SCOS8S} z

Step 11: Ca11 subroutine VESTIB to integrate the

15 differentia1 equations describing the ïestibu1ar mode1s and thereby obtain

ips'

~SS

(see Figure 4.4)

"

A

f w

,It ~S -SS

Step 12 : Compare resu1ts of Steps 11 and 6 to

obtain the vestibu1ar errors:

"

.

A' eAi

₌

_{f ps} 1

_-

_{fl . i}

₌

_x,y,z fp PA' A A eA.

₌

_jss

-

_{jAA; j}

₌

p,q,r wJ

Step 13: Ca11 subroutine OUTP to plot all the

required variables and store actuator time histories on file as required.

1"

STOP

Figure 4.3 Conc1uded

!p,

wand vestibular time constants - from main program

Step A-l: Generate vestibular coefficients

Step A-2:

(See Equations 2.6 to 2.9 and 2.16 to 2.19)

Call subroutine DGEAR (IMSL) to solve the 15 differential equations describing the vestibular model (given in subroutine FCNl)

"

Step A-3: FCNl calls subroutine INTERP to linearly interpolate for values of ip and, w at any time t from time histories stored-at 20

Hz.

'f

--RETURN )

t:l UJ 0 ~ a:: l -... V') (l... en ... :L :::s:: a:: l -lD lD X > :.E :::s:: a: t-... V')

>

-V') ... t:l UJ 0 ₀ a 0 a :::s:: 0 a:: l -V') a:: a 0 I/) 7.5 15.0 7.5 TIME (5) TIME 0 In I/) . N ... 0

-V') ... V') ... :.E 0 0 a ... 0 0 :::s:: 0 a: t-Cl: (l... X Cl: 0 In I/) N ... . 1i'.0 _{7.5 15.0} IT. 0 7.5 TIME ( S) _TIME a I/) ar---~---~ l"-In a a a a a Ir. 0 V') ... V') ... :.E 0 0 :::s:: ₀ a: t-a:: (l... >-Cl: I/) I"-

.

7.5 15.0 1)'.0 7.5 TIME ( 5) _TIME

Figure 4.5 Truck, Double Lane Change Maneuver Vehicle Motion " 15.0 (5 ) 15.0 IS) 15.0 IS)

,(Hl t - I - - _ VEHICLE TRAJECTDRY ROAD ~ Ol---~---+3.66

I

SHOULDER

o

50 X (Hl 100

Figure 4.5 Continued. Truck, Double Lane Change Maneuver

(/') ... (/') ... ~ g

·

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_.

...

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....

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·

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·

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·

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....

l:) UJ Cl (;) (;) :s:: Cl U ::> a: l -a: (/') (;) U') 7.5 TIME (S) 7.5 TIME (S) 7.5 TIME (S)

Figure 4.5 Concluded. Truck, Double Lane Change Maneuver Driverls Motion Sensation

15.0

15.0

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.

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Figure 4.6 Simulator, Double Lane Change Maneuver Without Tilt-Coordination. Predicted Translational Motion

...

U> t.:) "'-UJ t.:) CJ W 0 0 0 a ~ a ei ... ei _~ en ... ... U> :c _U> 0... _0... a

:

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...

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Figure 4.6 Continued. Simulator, Double Lane Change Maneuver Without Tilt-Coordination. Predicted Rotational Motion.