Cueing Deceleration Forces for Auto Simulators

A System for Cueing Deceleration in Fixed Platform Automotive
Simulators Using Seat Belt Tension
Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the
Graduate School of The Ohio State University
By
Seth Shill
Graduate Program in Electrical and Computer Engineering
The Ohio State University
2019
Masters Committee
Irem Eryilmaz, Ph.d., Advisor
Lisa Fiorentini, Ph.d.

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Abstract
Cueing systems in the context of automotive simulators are used to mimic real world events such as road
noise and motion. A system for cueing decelerations in car simulators is demonstrated and discussed in
this report. The final outcome was a system for tensioning the seat belt on a driver with force proportional
to the deceleration forces in the simulation. Since lap and shoulder portions of the belt are controlled
separately, future work may be done to account for specific acceleration forces felt by the driver such as
gravity while driving over a hill.
1. Introduction
Simulators and particularly driver-in-the-loop (DiL) simulators eliminate the cost, risk, and inconvenience
of automotive testing by replicating real world scenarios indoors. Two types of simulators are referred to
in this report: motion platform simulators which imitate deceleration by tilting and/or translating the
driver, and fixed platform simulators which rely on cueing mechanisms such as road noise sound and
feedback through brakes and steering. Research shows without proper cueing, drivers tend to have higher
onset jerk during braking, higher maximum deceleration during breaking, higher corner acceleration,
worse lateral vehicle control, less precise position of the vehicle relative to a stopping marker, and brake
harder [1] [2] [3] [4] [5] [7]. This puts fixed-platform simulators at a significant disadvantage despite their
lower cost. To close this gap in performance, a solution is needed for fixed frame platforms that does not
require the use of expensive parts such as the heavy-duty hydraulic systems used in motion platforms.
This project focuses on one mechanism in particular to improve the driver’s perception of longitudinal
(lateral) deceleration: applying tension to the driver’s seat belt to simulate deceleration forces. In
particular, a system is developed to apply tension to the driver proportional to the longitudinal
deceleration force experienced by a driver in an equivalent real-world scenario. This system was
calibrated for the simulator at the Driving Dynamics Lab at the Center for Automotive Research (CAR) at
the Ohio State University.
The belt tensioning system consists of two servo motors that apply tension separately to the lap and
shoulder portions of the seat belt to imitate the forces felt during deceleration. Currently only longitudinal
deceleration is simulated but more forces (e.g. the effect of gravity when going down a hill) can be
incorporated by applying different tension forces to the lap and shoulder belt portions respectively. The
final system built into the simulator at Driving Dynamics Lab has 4 unique tension forces corresponding
to four different longitudinal deceleration ranges. Each range represents different driving situations that
can be experienced by the driver in a real-world scenario.

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It is worth noting that this project does not focus on providing precise feedback in force; that is, forces felt
by the driver due to seat belt tensioning do not necessarily need to be equivalent to the actual deceleration
forces felt while driving. Instead, the system focused on improving perceptual feedback (the accuracy to
which a driver perceives deceleration) which can be measured in braking performance and stopping
distance among other measurement techniques.
2. Simulator Overview
To understand the project’s objectives, it is beneficial to understand the overall simulator and how
acceleration cueing fits into the bigger picture. The simulator’s intended use is for educational purposes
and to assess and develop the requirements and technologies for DiL facilities. This includes vehicle
dynamics, cueing, and scenario generation. Multiple components are already in place to implement these
features including a visual system which provides path control and a sense of path error, torque feedback
through the steering wheel, the motion platform (with three degrees of freedom), and human-machine
interface such as the heads-up display and steering wheel buttons. Other cueing systems exist (e.g. tire-
screeching sounds), with the seat belt tension system as the latest addition to cueing systems. All systems
are highly tuned to industry standards to provide an accurate simulation of driving distinctly different
from that of entertainment simulators. The physical system is shown in Figure 1.
Figure 1. Car simulator at the Driving Dynamics Lab.

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3. Design Overview
The project’s objective to apply different amounts of seat belt tension proportional to the lateral
deceleration computed in Simulink was completed in three parts: successful design and construction of a
mechanical system to deliver tension to the driver’s seat belt, communication network between the
Simulink model on a PC and belt tension actuators, and accurate control of seat belt tension based on
model data (i.e. driver feedback and model terrain).
3.1. Mechanical Design
At its most basic level, this project consists of a three-point seat belt where the buckle (colored red in
Figure 2) decouples the seat belt such that the lap and shoulder portions of the belt can be tightened
independently using servo motors. This two-part design allows for a more accurate representation of
forces a driver may experience. For example, tension felt in the shoulders might simulate the effect of
braking in the real world by moving the torso moving forward; on the other hand, tension in the lap would
simulate the sensation of a body lifting out of the seat when going down a hill.
Figure 2. Seat belt and servo configuration showing which end of the belt is associated with each.
Delivering tension to the seat belt required multiple steps starting from seat belt construction to the force
transfer between the servo motors and seat belt. Effectively transferring force required trading off
between supplying sufficient torque gain to the seat belt without sacrificing precision loss due to higher
gear ratios having less precision. This was achieved as described in Sections 3.1.1 and 3.1.2 describe the
calculations to meet those requirements.

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3.1.1. Mechanical System Requirements
Based on research done by S. de Groot et al., it was found that 150 N was the highest seat belt tension
force still considered comfortable by the drivers in the study and that increments of 50 N were clearly
observed by these same participants [7]. These parameters were used to set the range and resolution
respectively of the tensioning system. The free body diagram in Figure 3 depicts these forces.
Note that the study did not mention frictional losses due to seat belt design / setup (such as belt clips that
allow the seat belt to be re-routed, which increase friction to the seat belt). Therefore, the values
mentioned were used solely as guidelines.
Figure 3. Free body diagram of seat belt tension forces applied to the driver.
Relating this maximum seat belt tension to the system, which dispenses the seat belt using a spool of belt
with a given radius, the maximum force can be related to a maximum torque required T max at the seat
belt dispenser as
Tmax = Ftension,max ⋅ rdispensor = 150 𝑁 ⋅ 0.03 m = 4.5 N ⋅ m (1)
where the radius was assumed to be the radius of the dispenser and varies with time based on how tightly
the seat belt is applied (i.e. since radius increases slightly as the seat belt ravels up into the dispenser to
tighten the belt), and also dependent on how large the driver is (larger drivers use more of the belt). These
differences in radius were considered minor and ignored in this study.
This calculation shows that torque requirements are significant and therefore a system to reduce these
requirements was necessary. This was done using a set of gears, utilizing the fact that gear ratios can
multiply torque at the compromise of speed. Since speed was considered less essential for a small set of
gears, this compromise seemed reasonable. Therefore, a greater torque could be achieved using a source
of lesser torque generation.

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3.1.2. Calculating Gear Ratios
As can be seen in Figure 4, the tensional force acting as 𝐹3 is generated from much a smaller force at the
servo (green) using a ratio of gears. Rather than dispensing the seat belt from the servo directly, the servo
output shaft is attached to a larger gear (blue) via a belt. This larger gear is fixed to the seat belt dispenser
(red) such that both shafts spin in union. This lessens the torque required by the servo motor.
Figure 4. Free body diagram showing the forces acting on gear-and-pulley system attached to seat belt.
Based on the assumptions mentioned earlier, the tension force in the seat belt (𝐹3) is derived by starting
from the torque at the servo shaft as follows:
𝑇1 = 𝐹1 𝑟1 (2)
where 𝑇1 stands for the torque at Gear 1. Assuming that 𝑇1 𝑟1 = 𝑇2 𝑟2, it can also be said
𝑇2 =
𝑟2
𝑟1
𝑇1 (3)
Since Gear 2 and Gear 3 are fixed, we can say that
𝑇2 = 𝑇3 (4)
Since 𝑇3 = 𝐹3 ⋅ 𝑟3(𝑡) where the radius of the Gear 3 (seat belt spool) is a function of time as the spool is
wound up and unraveled. Therefore, we can say that
𝐹3 =
𝑇3
𝑟3(𝑡)
=
𝑟2
𝑟1
𝑇1
𝑟3(𝑡)
(5)
Given the maximum seat belt tension required (𝐹3 = 150 𝑁) and a rated servo torque of 𝑇𝑟𝑎𝑡𝑒𝑑 =
11.24 𝑖𝑛 ⋅ 𝑙𝑏 ≈ 1.27 𝑁𝑚, the gear ratio necessary to achieve this condition is calculated as:
𝑟2
𝑟1
=
𝐹3 𝑟3(𝑡)
𝑇1
=
150 𝑁 ⋅ 0.025 𝑚
1.27 𝑁 ⋅ 𝑚
≈ 2.95

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where we assume the seat belt dispenser spool radius is fixed at 𝑟3 ≈ 2.5 𝑐𝑚. It should be noted that while
there is no upper limit on how large Gear 2 can be, choosing a larger Gear 2 will reduce precision in seat
belt tension force since an equivalent change in torque will result in a proportionally larger change in
force at the seat belt. Also, note the torque chosen was the rated torque and not the peak torque value from
the specifications because peak torque cannot be reliably achieved at stall speeds.
Lastly, there are some important assumptions worth mentioning in this derivation. First, it was assumed
the belt does not slip as the shaft rotates. This allows us to treat the system as equivalent to spur gears.
Additionally, it was assumed that tension forces on the belt were the same on the top-side and bottom-
side of the belt, whereas typically there is a difference depending on the direction of rotation (clockwise
or counter-clockwise). Both these forces were assumed much larger than the centrifugal force acting on
the larger gear (inertial force of the gear).
The final implementation used XL-Series timing belt and two pulleys as gears custom-bored using
resources at CAR to fit the servo shaft and seat belt dispenser, respectively. Each gear was secured by a
lock nut provided by the manufacturer. More details on the construction of the gear train system is
described in 3.1.3.
3.1.3. Servo Housing, Belt Assembly, and Installation
Metal housing was fabricated for each servo to house the gear train assembly. Sliding bolt mounts
allowed for adjustment in the belt slack to ensuring proper tensioning (e.g. minimal slip, no
overtightening). This assembly included a retractor used to dispense slack in the seat belt. The retractor
was reconfigured to remove locking mechanisms and hold the belt in place using a modified spooling
cylinder. The belt itself was sewn together out of two real seat belts. These parts (except for the belt) are
shown in Figure 5, Figure 6, and Figure 7.
Figure 5. Housing exploded
view.
Figure 6. Dissembled retractor
housing.
Figure 7. Spooling cylinder

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Housing assemblies for both lap and shoulder belt portions control were located behind the driver’s seat.
These assemblies were each mounted on a single bolt allowing for rotation in the horizontal plane, and the
belt originating from each the assembly was threaded through clips to the driver’s seat at near identical
angles to the configuration in the 2018 Ford Mustang (the model car the simulator is based on). The B-
pillar of the car additionally had an adjustable belt clip for the shoulder belt to adjust height according to
regulations in the FMVSS 210. These configurations are shown in Figure 8 and Figure 9.
Figure 8. Shoulder & Lap Tensioning
Assemblies.
Figure 9. Anchorage Reference Angles - FMVSS
210.
3.1.4. Servo & Related Equipment Selection
As mentioned in the previous section, servos were chosen based on their ability to provide enough torque
at a reasonable cost. The Applied Motion Servo J0400-305-4-000 provides 1.27 𝑁𝑚 of torque which is
enough to supply the force needed in the system using gears to increase torque output (see Section 3.1.2).
Servo control including acceleration, torque, and direction, was conducted for each servo motor
separately via Applied Motion Servo Drive SV2D10-P-NE, which is Applied Motion’s low-cost option
for compatible controllers to the servo motors mentioned. These supplied enough torque control via I/O
ports as long as 0-10 V range could be achieved to reach the full operation range.
Two Mean Well model SE-600-48 were chosen as the power supply for each servo and controller pair. It
can provide 60 VDC input as specified by the Applied Motion servo. Note that while only 60 VDC is
required for each servo, each needs its own power supply to meet the demands of the system at maximum
power output (400 W per motor whereas the supply is 600 W). Typically, the power supply should be
well over the power requirements of the system.
Each servo drive itself is configured using free software (SVX Servo Suite) provided by Applied Motion
Products, Inc. A detailed guide on how this software is configured for this project is described in

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Appendix B: Torque Mode Configuration. Section 0 describes the servo input generation and software
control aspects of the belt tensioning system.
3.2. Communication & Signal Generation
Vehicle dynamics are generated through CarSim in Simulink. This software computes vehicle dynamics
from the simulation model’s terrain and driver input (such as braking, steering, etc). Once the deceleration
forces are computed, the computer sends two data signals (one for each the lap belt and shoulder belt) to
Arduinos over serial. Each Arduino then generates a pulse-width modulated (PWM) signal based on this
data, which then gets converted to an analog voltage suitable as input to the servo drive corresponding to
the lap or shoulder belt. Finally, this input voltage gets translated into a torque value by the servo drive
and sent to the servo to apply tension at each unique belt section. This process tension is outlined in the
flowchart in Figure 10. More details are described the following subsections.
Figure 10. Flow diagram highlighting signal transformation from start to end. The large boxed item is
repeated for the total number of nodes on the network (here 2; one node for each lap and shoulder servos
separately.
3.2.1. Software
Software control including the calculation of how much tension force was applied and what time is done
entirely based on vehicle dynamics generated in Simulink by CarSim software. The deceleration force in
the horizontal direction is calculated first in CarSim; that value then propagates to a lookup table (a block
type in Simulink) which maps the deceleration force to a PWM value depending on the servo drive. Each
servo has its own value mapping of the PWM values to lateral decelerations based on the circuit hardware
and the physical setup (e.g. whether it is lap or shoulder belt tension control). However, before PWM
values are sent to each Arduino through the serial interface, they are first converted to an unsigned 8-bit
integer and passed through a zero-order hold filter. This process ensures the right data type is passed to
Arduino and converts the signal value from a discrete sampled time signal to continuous time signal. The
Simulink model for this is shown in Figure 11.

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Figure 11. Simulink model showing how known horizontal deceleration forces are translated to PWM
values read by Arduino over serial ports.
As mentioned before, mappings between deceleration forces and output tension force are different for lap
and shoulder tension portions of the belt. Figure 13 summarizes how these tension forces are determined
once the deceleration force has been computed by CarSim. Four unique deceleration force ranges are
correlated to four different percentage values of total torque capacity. These percentage values were
chosen based on the student driver’s perception of force. These values are subject to change based on the
braking performance of trained drivers using the same simulator and same mechanism of applying tension
force.
3.2.2. Hardware Design
As mentioned earlier, servo motors are used to control torque on set of gears that ultimately adjust seat
belt tension. Control of AC synchronous servos is highly complex. Therefore, it is common to use
prebuilt controllers that implement torque control based on desired current, and program the servo
controllers according to the application. For this project, Applied Motion Servo Drives were purchased
due to their compatibility with the chosen servos and ease of use. Configuration for these drives is
programmed using SVX Servo Suite (provided for free by Applied Motion Products, Inc.) and input is

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through I/O ports. The exact setup used for this project is shown visually in the schematic in Figure 12
and described in Appendix B: Torque Mode Configuration.
Figure 12. Schematic for entire communication chain from PC to servo used in either the lap or seat belt
portion. Part of schematic taken from Applied Motion Servo Drive SV210 Manual cited in references.
To facilitate communication between the computer and these servo drives, it is necessary to create an
interface to translate the signal from digital to analog. The analog range for the servo drive input is 0-10
V. Thus, for this task, Arduinos were chosen to interpret the signal and a custom circuit built by Knacro
with digital-to-analog output and a built-in amplifier with gain 2 was used to translate the signal from the
Arduino’s PWM output (0-5 V) to the servo drive input. Choosing a custom prebuilt circuit shortened
development time with relatively little overhead cost.
3.2.3. Calculating Input Voltage to the Servo Drive
The PWM value (ranging 0-255) were determined from tension force in the seat belt involves multiple
steps. First, torque at the servo shaft needed to generate the force is calculated according to equation (5)
from 3.1.2. Then, the output current at the servo is determined based on the relationship between this
torque and current, that is
𝑇𝑠ℎ𝑎𝑓𝑡 = 𝑘 𝑡 𝐼 𝑜𝑢𝑡 (6)
or
𝐼 𝑜𝑢𝑡 =
𝑘 𝑡
𝑇𝑠ℎ𝑎𝑓𝑡
(7)

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where 𝑘 𝑡 is the torque constant provided by the servo manufacturer as 𝑘 𝑡 = 1.69 𝑙𝑏 ⋅ 𝑖𝑛/𝐴. Next, the
input voltage required to generate this current is calculated based on an input scale of 0-10 V:
𝐼 𝑜𝑢𝑡 =
𝑉𝑖𝑛𝑝𝑢𝑡
10 𝑉
𝐼 𝑚𝑎𝑥 (8)
and therefore
𝑉𝑖𝑛𝑝𝑢𝑡 =
𝐼 𝑜𝑢𝑡
𝐼 𝑚𝑎𝑥
⋅ 10 𝑉 (9)
where 𝐼 𝑚𝑎𝑥 = 7.5 𝐴 was chosen. This value allows the current setup to achieve the servo’s rated current
of 6.7 A (where the rated current is maximum sustainable current) since the gain of the circuit tested fell
slightly below the gain necessary to generate a 10 V signal input. Therefore 6.7 A could be achieved for
𝑉𝑖𝑛𝑝𝑢𝑡 =
6.7
7.5
≈ 9 𝑉. Finally, the PWM output voltage at the pin is determined by calibrating this voltage
signal with the programmed value. These calibrated values can be found in the results section. For more
information on how the servo drives are configured and operate as well as how to adjust the maximum
current parameter, please refer to Appendix B: Torque Mode Configuration.
4. Final Implementation Performance & Results
This section discusses the final system implementation and its performance. Additionally, servo torque
range and accuracy are measured and discussed in terms of their effect on system performance.
4.1. Final Implementation Performance
The final system implementation consists of four unique modes associated with four different
accelerations. These values are chosen based on student drivers’ (e.g. student researchers’) perceptions of
the smallest tension forces noticed, forces for which notable differences in tension was observed, and
maximum applied forces tolerable. Additional ranges could be added however participants in the study
(student drivers) felt this already provided a wide enough range of deceleration cues considering the
system previously had none.
Tension forces for each the lap and shoulder belt portions are adjusted according to each acceleration. For
the lowest acceleration mode at 𝑎 𝑥 = 0.5 𝑔, these values are set to 12% and 8% of total available torque
for the shoulder and lap belt portions, respectively. In contrast, when 𝑎 𝑥 = 1.1 𝑔 (the highest
acceleration) these values are set to 48% and 32%. The two other modes are for 𝑎 𝑥 = 0.75 𝑔 and 𝑎 𝑥 =
1.0 𝑔, in which case the lap and shoulder belt tensions are set to 24% and 16%, and 36% and 24%
respectively. This is shown visually in Figure 13.

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Figure 13. Threshold-based model implemented in Simulink. The different horizontal (x-hat)
accelerations correspond to relative tension force as a percentage of servo torque capacity. Note that
Chest Belt refers to shoulder belt (photo courtesy of Jaxon Wilkerson).
It should be noted that force values are measured relative to percentage of torque capacity only because a
system for accurately measuring forces felt by the driver was not necessary. Measurements could be made
later and compared to the actual deceleration forces experienced by the driver, however a comparison of
braking performance (not yet done) would be the most accurate means to demonstrate improvement in
drivers’ perception of deceleration. Also, the shoulder belt tension was always assumed to be higher than
the lap belt tension due to the fact that the shoulder belt acts more directly in the direction of acceleration
(𝑥̂-direction) simulated. Future improvements accounting more specifically for vertical acceleration (in
the case of going over a hill, for example), would require additional modes to account for the unique
tension forces in the lap and shoulder belt portions felt in that scenario.
4.2. Results: Measured Torque Range & Accuracy
Observed servo torque output was recorded by measuring the force output at the gear on the shaft of the
servo. The test setup consists of a heavy-duty vice grip (top in picture) to hold the servo in place, a wedge
(top left) to prevent lateral movement in the vice grip (which is held down by only 1 bolt), a 1.375-inch
diameter gear attached to the servo’s shaft, a luggage scale (below) held down by its handle using a
washer and bolt, and 50-lb fishing wire (difficult to see) tied at one end to the luggage scale’s hook and to
the gear on the servo at the other end. Fishing wire was chosen to have the least impact on measurements
due to being lightweight and small in diameter. This setup is shown in Figure 14.

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Figure 14. Test setup used to measure force and thereby torque exerted by the servo.
Table 1 shows both the observed and predicted (or calculated) force values in 1 V increments in input (or
0.75 A). It assumes a gear shaft diameter of 1.375 in, torque constant 𝑘 𝑡= 1.69 in-lb / A, and maximum
output current 𝐼 𝑚𝑎𝑥 = 7.5 A at 10 V input. The column labels are as follows: “Current” is the output
current calculated as 𝐼 =
𝑇1
𝑘 𝑡
, where 𝑘 𝑡 is the torque constant provided by the servo. “Voltage” is the
analog input voltage expressed as 𝑉 =
𝐼
𝐼 𝑚𝑎𝑥
⋅ 10 𝑉 where the denominator term is set to 7.5 A. “Digital”
refers to the integer PWM value (range 0-255) used to program Arduino’s output. “Torque” is the torque
at the shaft calculated based on equation 5, converted to units of lb-in assuming 8.85 lb-in / Nm. “Calc.
Force” is the force calculated at the output gear, while “Measured Force” is the observed force at the
same gear. Figure 15 shows a comparison plot between the predicted force at the gear output and
observed force.
Table 1. Measured and predicted force generated at output gear shaft of the servo drive.
Current (A)
(+/- 0.05 A)
Voltage (V)
(+/-0.05 V)
Digital Pin (0-
255)
Torque (lb-in)
(+/-0.05 lb-in)
Calc. Force (lb)
(+/- 0.5 lb)
Measured Force
(+/- 0.5 lbs)
0.75 1 19 1.3 2 1
1.50 2 42 2.5 4 3
2.25 3 66 3.8 6 4
3.00 4 91 5.1 7 7

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3.75 5 119 6.3 9 9
4.50 6 147 7.6 11 12
5.25 7 176 8.9 13 14
6.00 8 208 10.1 15 16
6.75 9 243 11.4 17 19
Figure 15. Plot of input voltage versus output force at servo drive shaft.
Results verified tension force precision and range could be achieved according to those results found by
S. de Groot et. al. [6]. In particular, the maximum force at Gear 1 was found to be 19 lb as shown in Table
1.This corresponds to a tension force of
𝐹𝑡𝑒𝑛𝑠𝑖𝑜𝑛,𝑚𝑎𝑥 = 𝐹3,𝑚𝑎𝑥 =
𝑟2 𝐹1,𝑚𝑎𝑥
𝑟3
=
3.036 𝑖𝑛
1 𝑖𝑛
(19 𝑙𝑏) ≈ 57 𝑙𝑏 ≈ 253 𝑁)
based on equation (5). Of course this maximum value depends highly on 𝑟3, but as long as 𝑟3 < 1.7 𝑖𝑛 the
tension force still achieves the maximum desired force of 150 N.
The required precision was also verified by the maximum observed error between predicted (calculated)
values and observed values. In the worst case it was observed that a 2-pound difference would result in a
force error of
ℰtension = ℰGear 2
𝑟2
𝑟3
= 2 𝑙𝑏 (
4.12 𝑖𝑛
1 𝑖𝑛
) ≈ 8.25 𝑙𝑏 ≈ 36 𝑁.
This error may have arisen due inaccuracy in the measurement scale (which did not provide ratings for
accuracy) and/or setup (e.g. suboptimal angles requiring the scale to flex at slight angles). However, it still
Red – Observed Value
Blue – Predicted Value

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falls below the minimum required precision of 50 N as observed by [6], the change in force which is
clearly recognized by all participants in the study mentioned earlier.
Lastly, Figure 15 demonstrates from the data in Table 1 that input voltage is linearly related to output
force as predicted and as desired. It is also noted that digital values for the PWM input to the Arduino
were calibrated for the required input voltage to the servo drive, 𝑉𝑖𝑛𝑝𝑢𝑡, and these calibration values are
found in Appendix C: Knacro® Circuit Calibration. These results show slight variations in performance
between each digital to analog converter circuit however this did not affect system performance because
values were simply calibrated to meet requirements as shown in that section.
5. Conclusions & Future Work
In this project, the system provides the needed perception of deceleration for the driver at different
deceleration values and can be tuned more accurately to provide accurate feedback to trained drivers.
Results proved the capability to create a seat belt tensioning system with a range of forces calibrated
based on four different deceleration ranges. While this is sufficient for initial testing with student drivers
it will need to be calibrated more accurately to accommodate the system’s intended user (trained drivers).
Accuracy in the delivery of force could be improved by removing sources of frictional loss, particularly
from the belt rerouter located on the B-pillar. Additionally, a greater variation in ranges can be added as
the system as it is tested by trained drivers and additional measurements are made to determine the actual
tension force in the lap and shoulder portions of the belt. Lastly, improvements from tuning lap and
shoulder portions of the belt separately can be used to account for unique scenarios such as hills. These
tests could be verified by measuring stopping performance (e.g. stopping distance, deceleration, etc.) and
comparing to real world results.
6. References
[1] Brunger-Koch, M., Briest, S., & Vollrath, M. (2006). Virtual driving with different motion
characteristics: Braking maneuver analysis and validation. In Proceedings of the Driving
Simulation Conference, 69–78.
[2] Colombet, F., Dagdelen, M., Reymond, G., Pere, C., Merienne, F., & Kemeny, A. (2008). Motion
cueing: What is the impact on the driver’s behavior? In Proceedings of the Driving Simulation
Conference, 171–181

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[3] Greenberg, J., Artz, B., & Cathey, L. (2003). The effect of lateral motion cues during simulated
driving. Paper presented at the driving simulation conference North America, Dearborn,
Michigan. Retrieved from
http://www.nadssc.Uiowa.edu/dscna07/dscna_cd2003/papers/Greenberg_The%20effect%20of%
Lateral%20Motion%20Cues….pdf
[4] Pinto, M., Cavallo, V., Ohlmann, T., Espie´, S.,&Roge´, J. (2004). The perception of longitudinal
accelerations: What factors influence braking manoeuvres in driving simulators? In Proceedings
of the Driving Simulation Conference, 139–151.
[5] Reymond, F., Kemeny, A., Droulez, J., & Berthoz, A. (2001). Role of lateral acceleration in
curve driving: Driver model and experiments on a real vehicle and a driving simulator. Human
Factors, 43, 483–495.
[6] S. de Groot, J. C. F. de Winter, M. Mulder, P. A. Wieringa. (2011) Nonvestibular Motion Cueing
in a Fixed-Based Driving Simulator: Effects on Driver Braking and Cornering Performance. In
Presence, 20 (2), pp. 117-142.
[7] Siegler, I., Reymond, G., Kemeny, A., & Berthoz, A. (2001). Sensoriservo integration in a
driving simulator: Contributions of motion cueing in elementary driving tasks. In Proceedings of
the Driving Simulation Conference, 21–32.
[8] "SV200 Series Servo Drive". Applied-Motion.Com, 2019, https://www.applied-
motion.com/sites/default/files/hardware-manuals/SV200%20DC%20Hardware%20Manual_920-
0126B.pdf. Accessed 25 Apr 2019.

18
Appendix A: Materials Used
Table 2. List of Materials Used
Applied Motion Servo Drive (Model: SV2D10-P-NE)
Applied Motion J0400-305-4-000
XL-Timing Belt Pulley, 1.375’’ OD
XL-Timing Belt Pulley, 3.036’’ OD
XL-Series Timing Belt
Knacro PWM-to-Voltage Module
Breadboards & wires
Arduino Uno
12V Power Supply
Appendix B: Torque Mode Configuration
For the most part, the 4-step process outlined on page 106 of the servo drive manual (see references) was
followed with certain caveats; first, a custom motor configuration was used was used based on the servo
specifications. This was adjusted as shown in the image below (8 poles, 6.90 A Continuous Current, 20.7
A Peak Current, 1000 counts/rev, CW option, 15-pin wiring as shown in image below). Additionally, in
the GUI under “Step 4. Input & Output”, variable X3 was set to “Not used (Servo Off when power-up)”.
Figure 16. Servo Motor configuration in SVX Servo Suite.

19
As discussed in the report, torque mode configuration was desirable for the servo drive in order to have
precise control of the tension applied to the seat belt. This mode was configured in software as shown
below. Torque is controlled via current through the input pin 17 of port CN2 (see Figure 12). This input
took analog voltage in the range of -10 to 10 V. For our case where torque is only applied in 1 direction, a
range of 0-10 V is used.
Figure 17. Torque mode configuration in SVX Servo Suite software.
Additional adjustments were made to condition the output torque more precisely. A speed limit of 25 rps
(rotations per second) was chosen to avoid tightening the seat belt too quickly on the driver. This can be
adjusted manually up to values of 100 rps by entering the following SCL commands in SVX Servo Suite
as shown in Figure 18:
VM X
SA
where VM stands for velocity maximum, X should be replaced by the maximum desired velocity, and SA
stands for save.

20
Figure 18. SCL command entry box in SVX Servo Suite software.
A maximum current of 7.5 A was chosen since this would provide
9 𝑉
10 𝑉
× 7.5 𝐴 = 6.75 𝐴 ≈ 6.7 𝐴; that is,
the maximum continuous current is reached at the maximum input voltage achievable by the PWM to
Analog signal amplifier circuit, equivalent to ~9.13 V. These settings are in the SVX Servo Suite GUI, “4.
Input & Output” under the tab “Analog Input” as pictured in Figure 19.
Figure 19. Analog input tab under “Input & Output” in SVX Servo Suite software.
Figure 20 shows the tuning configuration used, which should be that of the default settings.
Figure 20. Gain settings (also adjusted in SVX Servo Suite).

21
Appendix C: Knacro® Circuit Calibration
Table 3. Voltage input to servo drive and its corresponding PWM value in Simulink for boards #1 and #2.
Input Voltage
(V)
Board #1
Digital (0-255)
Board #2
Digital (0-
255)
1 19 19
2 42 41
3 66 63
4 91 86
5 119 111
6 147 136
7 176 163
8 208 193
9 243 219
Figure 21. Calibration curve of voltage versus byte value.
0
50
100
150
200
250
300
0 2 4 6 8 10
ByteValue(0-255)
Voltage (V)
PWM Voltage vs. Byte Representation

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