Denial of Motor Vehicle Defect Petition |
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Topics: Tesla
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Jeffrey Mark Giuseppe
National Highway Traffic Safety Administration
13 January 2021
[Federal Register Volume 86, Number 8 (Wednesday, January 13, 2021)]
[Notices]
[Pages 2733-2739]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-00501]
[[Page 2733]]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
[Docket No. NHTSA-2019-0105]
Denial of Motor Vehicle Defect Petition
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation.
ACTION: Denial of petition for a defect investigation.
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SUMMARY: This notice sets forth the reasons for the denial of a
petition submitted on December 19, 2019, by Mr. Brian Sparks to NHTSA's
Office of Defects Investigation (ODI). The petition requests that the
Agency recall Tesla vehicles for an unidentified defect that allegedly
causes sudden unintended acceleration (SUA). NHTSA opened Defect
Petition DP20-001 to evaluate the petitioner's request. After reviewing
the information provided by the petitioner and Tesla regarding the
alleged defect and the subject complaints, NHTSA has concluded that
there is insufficient evidence to warrant further action at this time.
Accordingly, the Agency has denied the petition.
FOR FURTHER INFORMATION CONTACT: Mr. Ajit Alkondon, Vehicle Defects
Division--D, Office of Defects Investigation, NHTSA, 1200 New Jersey
Ave. SE, Washington, DC 20590 (telephone 202-366-3565).
SUPPLEMENTARY INFORMATION:
1.0 Introduction
Interested persons may petition NHTSA requesting that the Agency
initiate an investigation to determine whether a motor vehicle or item
of replacement equipment does not comply with an applicable motor
vehicle safety standard or contains a defect that relates to motor
vehicle safety. 49 U.S.C. 30162; 49 CFR part 552. Upon receipt of a
properly filed petition the Agency conducts a technical review of the
petition, material submitted with the petition, and any additional
information. 49 U.S.C. 30162(c); 49 CFR 552.6. After considering the
technical review and taking into account appropriate factors, which may
include, among others, allocation of Agency resources, Agency
priorities, and the likelihood of success in litigation that might
arise from a determination of a noncompliance or a defect related to
motor vehicle safety, the Agency will grant or deny the petition. 49
U.S.C. 30162(d); 49 CFR 552.8.
2.0 Petition
2.1 Petition Chronology
Mr. Brian Sparks (the petitioner) first submitted a valid petition
conforming to the requirements of 49 CFR 552.4 on December 19, 2019.\1\
On December 30, 2019, the petitioner submitted an addendum to his
petition. This addendum references NHTSA complaint 11291423, which
alleges unexpected movement of a vehicle that was parked and
unoccupied.
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\1\ The petitioner first raised concerns about SUA in Tesla
vehicles in September 2019 correspondence with the Agency. NHTSA did
not consider this earlier correspondence to be a validly submitted
petition because the petitioner did not provide his name and
address. See 49 CFR 552.4. The September 2019 letter cited 110
incidents of alleged SUA in complaints to NHTSA, including 102
reporting crashes. NHTSA has included the information in
petitioner's September 2019 correspondence in the Agency's analysis
of the petition.
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On January 13, 2020, the Office of Defects Investigation (ODI)
opened Defect Petition DP20-001 to evaluate the petitioner's request
for a recall of all Tesla Model S, Model X, and Model 3 vehicles
produced to date based on the information in his correspondence,
petition and various addendums. On February 21, 2020, the petitioner
submitted another addendum to his petition, identifying 70 new
incidents of alleged SUA in NHTSA complaints (also known as Vehicle
Owner Questionnaires, or VOQs) filed since DP20-001 was opened.
Additional addendums updating VOQ counts were submitted on April 10,
2020, June 22, 2020, September 10, 2020 and December 1, 2020. The June
22 submission included a request to update the petition ``to include a
recent analysis of Tesla's SUA defect from Dr. Ronald Belt.''
2.2 Petition Basis
Altogether, the petitioner identified a total of 232 VOQs involving
unique alleged SUA incidents in his submissions, including 203
reporting crashes.\2\ The petitioner also submitted a document
purporting to analyze Event Data Recorder (EDR) data from the incident
reported in NHTSA VOQ 11216155. The petitioner believes that ``Tesla
vehicles have a structural flaw which puts their drivers and the public
at risk'' and bases his request for a recall of the subject vehicles
on:
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\2\ The petitioner identified a total of 225 VOQ in the original
petition and five addendums. Six of the VOQs are duplicative of a
prior VOQ.
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1. His view that, ``The volume of complaints in the NHTSA database
indicates a severe and systemic malfunction within Tesla vehicles;''
2. A third-party analysis of data from the crash reported in VOQ
11206155, which theorizes a fault condition that allegedly ``caused the
brake pedal to behave like an accelerator pedal;'' and
3. A complaint (VOQ 11291423) alleging SUA while the driver was
outside the vehicle, which the petitioner describes as ``the first SUA
complaint involving a Tesla vehicle in which the driver cannot
reasonably be accused of pressing the accelerator.''
3.0 Analysis
ODI performed the following analyses in its evaluation of the
petition for a grant or deny decision:
1. Analyzed crashes identified by petitioner for connection to SUA;
2. Analyzed EDR or Tesla vehicle log data or both from 118 crash
incidents; \3\
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\3\ This information was not available or not obtained for the
remaining crash incidents, as detailed below.
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3. Reviewed the crash incident reported in VOQ 11206155;
4. Reviewed the crash incidents reported in VOQ 11291423;
5. Reviewed Tesla's system safeguards for the accelerator pedal
position sensor (APPS) assembly and motor control system;
6. Reviewed two defect theories referenced in the petition;
7. Reviewed the brake system designs for the subject vehicles; and
8. Reviewed service history information for the accelerator pedal
assemblies, motor control systems, and brake systems for 204 of the 232
vehicles identified in VOQs submitted by the petitioner.\4\
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\4\ ODI's information request letter for DP20-001 requested
crash data and service history information for all 124 VOQs cited in
the original petition and the first two addendums submitted by the
petitioner. On February 10, 2020 and October 20, 2020, ODI requested
certain supplemental information for a total of 83 additional VOQs
alleging crashes, including 80 that were cited in addendums
submitted by the petitioner.
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3.1 Crash Classification
ODI's crash analysis reviewed 217 incidents, including the 203
crashes identified by the petitioner and fourteen additional crashes
reported in VOQs that were either not selected by the petitioner
(eight) or were submitted after the petitioner's most recent submission
(six).
Table 1 provides a breakdown of the driving environments and crash
data review for the crashes analyzed by ODI. Crash data (EDR, Tesla log
data, and/or video data) were reviewed for 118 of the crash incidents.
Crash data were not obtained for most of the incidents received after
DP20-001 was opened.
[[Page 2734]]
Table 1--Summary of Crash Incidents Reviewed by ODL
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Crash data Crash data Crash data
Category reviewed not available not obtained Total
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Parking lot..................................... 61 44 9 114
Driveway........................................ 26 16 4 46
Traffic light................................... 11 7 2 20
Parking garage.................................. 7 5 1 12
City traffic.................................... 3 1 0 4
Stop-and-go traffic............................. 2 2 0 4
Highway traffic................................. 2 1 1 4
Stop sign....................................... 2 1 0 3
Charging station................................ 1 1 1 3
Street side parking............................. 1 1 0 2
Drive thru...................................... 1 0 1 2
School drop-off lane............................ 1 0 0 1
Car wash........................................ 0 1 0 1
Gated exit (China incident)..................... 0 1 0 1
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Total....................................... 118 80 19 217
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Six of the crashes reported by the petitioner were assessed by ODI
as unrelated to SUA. These include all four of the crashes occurring in
highway traffic, one crash at a traffic light and one of the driveway
crashes. The highway crashes include two involving loss of lateral
control due to apparent loss of rear tire grip while driving in the
rain (VOQs 11297507 and 11307255), one involving late braking for the
cut-in of a slower moving vehicle (VOQ 11278322), and one for which the
crash data do not support the allegation and show no evidence of speed
increase or failure to respond to driver inputs (VOQ 11174732). The
crash at a traffic light involved unexpected movement of a vehicle
operating with Traffic Aware Cruise Control enabled after the vehicle
had come to a stop behind another vehicle at a red light (VOQ
11307023). The driveway crash incident will be reviewed later in this
report (VOQ 11291423).
All of the remaining 211 crashes, assessed by ODI as related to
SUA, occurred in locations and driving circumstances where braking is
expected. Eighty-six (86) percent of these crashes occurred in parking
lots, driveways or other close-quarter ``not-in-traffic'' locations.
Almost all of these crashes were of short duration, with crashes
occurring within three seconds of the alleged SUA event.
3.2 SUA Crash Data Analysis
ODI's analysis of EDR data, log data or both from 118 crashes did
not identify any evidence of a vehicle-based cause of unintended
acceleration or ineffective brake system performance in the subject
vehicles. The data shows that vehicles responded as expected to driver
accelerator and brake pedal inputs, accelerating when the accelerator
pedal is applied, slowing when the accelerator pedal is released
(generally in regenerative braking mode) and slowing more rapidly when
the brake is applied. ODI did not observe any incidents with vehicle
accelerations or motor torques that were not associated with
accelerator pedal applications. In the few cases where the brake and
accelerator pedal were applied at the same time, the brake override
logic performed as designed and cut motor torque.
The data clearly point to pedal misapplication by the driver as the
cause of SUA in these incidents. Analysis of log data shows that the
accelerator pedal was applied to 85 percent or greater in 97 percent of
the SUA crashes reviewed by ODI. Peak accelerator pedal applications
were initiated within two seconds of the collisions in 97 percent of
the cases. Analysis of brake data showed no braking in 90 percent of
SUA crashes and late braking initiated less than one second before
impact in the remaining 10 percent. The pre-crash event data and driver
statements indicate that the SUA crashes have resulted from drivers
mistakenly applying the accelerator pedal when they intended to apply
the brake pedal. Approximately 51 percent of the crashes occurred in
the first six months of the driver's use of the incident vehicle.
3.3 VOQ 11206155
3.3.1 Consumer's Description of the Event
NHTSA complaint 11206155 alleges that a 2018 Tesla Model 3
experienced an SUA event resulting in a crash in the owner's driveway
on the evening of May 6, 2019. The complaint states that:
``[The driver] turned into [the driver's] driveway and was going to
pull into [her] garage to park the car, when the car accelerated
suddenly and violently and crashed into the front stone wall of [the]
house. The stone wall is damaged and the front right side of the Tesla
has significant damages.''
The petitioner referenced the incident reported in VOQ 11206155 in
the first addendum to the petition,\5\ which included a third-party
analysis of EDR data from the crash. ODI requested a copy of the EDR
data in the petition acknowledgement letter. In response, the
petitioner provided an incomplete copy of the EDR, a copy of a letter
Tesla sent to the consumer, and a document prepared by the driver that
provides additional details about the SUA allegation.\6\ The driver
alleges that the SUA event occurred after the vehicle was ``slowed to a
halt'' and while the driver was ``waiting for the garage door to fully
open.''
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\5\ Email from Brian Sparks to NHTSA Acting Administrator Owens,
``Motor Vehicle Defect Petition: Recall Tesla Vehicles Due to Sudden
Unintended Acceleration,'' December 19, 2019.
\6\ Email from Brian Sparks to ODI, ``Re_DP20-001
Acknowledgement Letter,'' February 21, 2020, attachment titled ``My
Experiences with Tesla Model 3.''
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3.3.2 Tesla Letter to the Consumer
In a July 11, 2019 letter, Tesla provided the consumer with the
following summary of its analysis of log data for the crash event
reported in VOQ 11206155: \7\
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\7\ Tesla service manager, letter to the consumer, July 11,
2019.
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``According to the vehicle's diagnostic log, immediately prior to
the incident, the accelerator pedal was released, regenerative braking
was engaged and slowing the vehicle, and the steering wheel was turned
to the right. Then, while the vehicle was traveling at approximately 5
miles per hour and the
[[Page 2735]]
steering wheel was turned sharply to the right, the accelerator pedal
was manually pressed and over about one second, increased from
approximately 0% to as high as 88%. During this time, the vehicle speed
appropriately increased in response to the driver's manual accelerator
pedal input. In the next two seconds, the accelerator pedal was
released, the brake pedal was manually pressed, which also engaged the
Anti-Lock Braking System, multiple crash-related alerts and signals
were triggered, and the vehicle came to a stop.''
3.3.3 ODI Analysis of the Event
ODI's analysis of the subject crash event included reviews of
vehicle log data, the EDR report furnished by the petitioner,
statements from the driver, and a video of the incident provided by
Tesla. This analysis confirmed the sequence of events described in
Tesla's letter to the consumer. Figure 1 shows pre-crash vehicle speed
and driver controls over the ten seconds prior to impact.
ODI's review of the vehicle log data shows that, approximately
seven seconds before the crash, the vehicle is completing a right turn
as the steering angle returns from a large positive value to neutral.
Over the next second, the driver releases the accelerator pedal and the
vehicle begins a moderate deceleration under regenerative braking. The
vehicle begins to turn right toward the owner's driveway approximately
five seconds before impact. Approximately two seconds before impact, as
the vehicle nears the apex of the turn into the driveway, the
accelerator pedal position begins to increase. The accelerator pedal
increases from 0% to 88% in about one second.
BILLING CODE 4910-59-P
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[GRAPHIC] [TIFF OMITTED] TN13JA21.007
BILLING CODE 4910-59-C
The accelerator pedal returns to 0% approximately 0.9 seconds before
impact and the brake pedal is applied approximately 0.5 seconds later.
The late brake application initiates ABS braking approximately 0.2
seconds before impact.
3.3.4 ODI Analysis of Event Video File
An event video file from the vehicle's front camera sensor shows
the vehicle moving slowly on a residential street before beginning the
right turn into a short driveway with a moderate positive grade leading
to twin garage doors separated by a center pillar covered by stonework.
The vehicle briefly surges forward as it nears the apex of the turn
into the driveway. The vehicle never stops moving and continues to turn
right until impacting the center pillar, consistent with the steering
angle data
[[Page 2737]]
from the log and EDR data. The garage doors remain closed throughout
the event.
3.3.5 ODI Analysis of EDR Data
The EDR vehicle speed, accelerator pedal position and steering
angle data mirror the log data, within the range of expected variation
due to differences in data resolution, sampling intervals and data
latencies in the two data recording systems. For example, the vehicle
speed data reported in the EDR report for the Model 3 has a resolution
of 1 mph, a sampling frequency of 5 Hz, and a maximum latency of
approximately 200 milliseconds, while the vehicle speed data recorded
in the log data has a resolution of 0.05 mph, a logging rate of 1 Hz,
and a maximum latency of approximately 10 milliseconds.
The EDR did not record the late brake application and subsequent
ABS activation. The data log shows that the Restraint Control Module
(RCM) echoed the brake application in the near deployment alert
triggered by the impact, indicating that the EDR would be expected to
show ``On'' for service brake status at impact. Tesla indicated it was
unable to investigate the apparent discrepancy further without an
original copy of the EDR report.\8\
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\8\ This is the only event reviewed by ODI in this petition
evaluation where the data log showed the brake was applied at T0 and
the EDR did not.
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ODI's reviews of EDR reports for this and several other Model 3
crash events noted that the polarity of the pre-crash longitudinal
acceleration data appeared to be reversed in relation to vehicle speed
data (i.e., negative acceleration displayed when the vehicle speed is
increasing and positive acceleration displayed when vehicle speed is
decreasing).\9\ Tesla confirmed that the longitudinal acceleration data
polarity was reversed in Model 3 EDR reports produced using EDR
reporting services of v20.2.1 or earlier. Tesla advised ODI that the
error has been corrected in EDR reporting service update v20.29.1.
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\9\ Acceleration (a) is the change in velocity (v) per unit time
(t), or a(T) = dv/dt. When vehicle speed is increasing over a given
time interval, the acceleration is positive in that interval.
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3.4 Analysis of Log Data for VOQ 11291423
VOQ 11291423 alleges multiple incidents of unexpected movement of a
2015 Model S after parking on an inclined driveway in Lancaster,
California on December 26, 2019. The complaint states that:
``[The] 2015 Model S 85D was reversed onto driveway then placed in
park and doors were closed and locked. A few moments later the vehicle
started accelerating forward towards the street and crashed into a
parked car. Front wheels were receiving power while rear wheels where
locked and dragging rather than wheels spinning. I reversed vehicle
back onto driveway and it happened another 2 times after first incident
within a 30 minute time span.''
As previously noted, the petitioner's addendum cited this VOQ as an
``SUA complaint involving a Tesla vehicle in which the driver cannot
reasonably be accused of pressing the accelerator.'' When interviewed
by ODI, the owner stated that the vehicle was backed up an inclined
driveway and parked. The driveway was covered with freshly fallen snow.
Shortly after he shifted to ``park'' and exited the vehicle, the owner
observed the vehicle move approximately two car lengths down the
driveway.
The movement stopped when the vehicle reached the level surface of
the street at the base of the driveway. The owner alleged the movement
occurred two more times after the vehicle was backed up the driveway
and parked in a similar position. The second incident involved a minor
impact with a vehicle parked within a couple of feet of the Tesla,
resulting in a crack in the front bumper of the second vehicle and no
damage to the Tesla. The third incident was like the first, with the
movement ending at the base of the inclined driveway.
ODI's review of log data from this vehicle found that the movement
occurred when the vehicle was shutoff with no torque applied to the
front or rear drive motors. Based on the log data and the physics of
the vehicle movement from the driveway to the street, it is ODI's
assessment that the unexpected movement of the parked vehicle was most
likely caused by insufficient traction of the rear tires on the low-
friction surface of the snow-covered driveway, which resulted in the
vehicle sliding down the driveway. ODI has excluded this incident from
its analysis of SUA crashes.
3.5 System Safeguards
The APPS system used in the subject Tesla vehicles has numerous
design features to detect, and respond to, single point electrical
faults, including: Redundant position sensors, contactless inductive
sensing technology, independent power and ground connections to the
sensors, and sensor voltage curves that differ by a fixed ratio.\10\
All subject vehicles are equipped with accelerator pedal assemblies
with two independent inductive sensors that convert the angular
position of the pedal to voltage signals. The pedal position can only
be changed in response to an external force being applied, such as the
driver's foot.
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\10\ Second channel output voltage curve is half the slope of
the first channel.
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The Drive Inverter main processor controls motor torque based on
accelerator pedal voltage. A separate processor (Pedal Monitor) acts as
a safety monitor, continually checking both APPS signals for faults and
independently calculating motor torque. Any malfunction or deviation in
the APPS system results in a fault mode, cutting torque to zero for
driver pedal applications or regenerative braking. In addition, the
Pedal Monitor can shut off the Drive Inverter if driver's commanded
motor torque and actual motor torque do not match.
The APPS voltage signals pass through A/D (Analog/Digital)
converters in the drive unit, which then reports the data to the
Controller Area Network (CAN) communication bus.\11\ The CAN data are
time stamped and stored at specified intervals by the data log. The RCM
receives the data from the drive unit via the CAN bus. The data is
buffered in the RCM random access memory (RAM) and then written to the
RCM Electrically Erasable Programmable Read-Only Memory (EEPROM) \12\
in the event of a non-deploy or deployment event.
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\11\ The APPS data refresh rate is 10 milliseconds.
\12\ The EEPROM is a non-volatile memory device that retains
stored data after cycling power.
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3.6 ODI Review of SUA Theories
As part of its evaluation of DP20-001, ODI reviewed two defect
theories alleging vehicle-based causes of SUA in the subject vehicles.
Both theories were developed by Dr. Ronald Belt, the first in 2018 and
the second in 2020. A paper describing the most recent theory was
submitted to NHTSA by the petitioner and is based upon Dr. Belt's
review of EDR data from the crash reported in VOQ 11206155. The other
theory was referenced by the consumer who submitted VOQ 11206155 and is
based upon Dr. Belt's third-hand reconstruction of log data from an
unknown SUA event. Both papers are based upon incorrect event data,
incorrect reconstructions of event dynamics, and false assumptions
regarding vehicle design factors.
3.6.1 2020 Theory (VOQ 11206155 SUA Event)
In an addendum to the petition submitted on June 22, 2020, the
petitioner requested that NHTSA include a recent paper by Dr. Ronald
[[Page 2738]]
Belt in his petition.\13\ The paper, dated June 1, 2020, claims to
explain how a ``faulty brake light switch [caused] the brake pedal to
behave like an accelerator pedal'' in the crash event reported in VOQ
11206155 that was reviewed earlier in this report (see section 3.3 VOQ
11206155). The same analysis alleges that the proposed theory ``is
believed to be the cause of sudden acceleration in over 70% of Tesla
vehicles.''
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\13\ Belt, Ronald. ``Tesla Regen, Brakes and Sudden
Acceleration.'' Center for Auto Safety, June 1, 2020. https://www.autosafety.org/wp-content/uploads/2015/03/Tesla-Regen-Brakes-and-Sudden-Acceleration.pdf.
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The SUA theory proposed by Dr. Belt in the June 2020 paper appears
to have originated from his reliance on the pre-crash longitudinal
acceleration data in the EDR report with the polarity issue recently
corrected by Tesla (see section 3.3.5 ODI Analysis of EDR Data). Rather
than recognizing the conflicts between the longitudinal acceleration
data and other pre-crash data in the EDR report (e.g., vehicle speed,
rear motor speed and accelerator pedal position all increasing over the
same time interval as the reported deceleration), Dr. Belt develops his
reconstruction of the crash event using the inverted longitudinal
acceleration data and posits a theory to explain how a faulty brake
light switch can cause the brake pedal to function like an accelerator
pedal. The theory relies upon numerous assumptions, including: A
defective brake switch, a large positive torque request from the
electronic stability control (ESC) system, an alternate explanation for
the large accelerator pedal position increase shown in the pre-crash
data, and an alleged veer to the left caused by the presumed ESC
activation.
ODI does not believe that Dr. Belt's June 2020 paper provides a
valid theory of an SUA defect in the subject incident or any other
crash. The theory is based upon inaccurate event data and several false
assumptions regarding component defects, vehicle dynamics, and motor
control system design and operation. For example, ODI notes the
following factual errors and mistaken assumptions contained the subject
paper:
The vehicle acceleration data used by Dr. Belt in his
analysis was reported with the polarity reversed. In other words, the
data shows the vehicle decelerating when it was accelerating and
accelerating when it was decelerating. As shown in Figure 1, the
vehicle first accelerates in response to a large accelerator pedal
application, then decelerates in response to the late brake application
that triggered ABS braking just prior to impact.\14\
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\14\ ODI estimates that the vehicle was within approximately
five feet of the stone wall when ABS braking began.
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The evidence shows that the brake light switch functioned
as designed in the event analyzed by Dr. Belt (see Figure 1).
The ESC and Traction Control systems cannot request
positive torque in the subject vehicles.
The APPS data recorded in the EDR report and data log show
the physical position of the accelerator pedal (see section 3.5 System
Safeguards). There is no other source for the accelerator pedal data.
The vehicle does not veer to the left at any point during
the crash event (see Figure 1 and section 3.3.4 ODI Analysis of Event
Video File).
3.6.2 2018 Theory (Unknown SUA Event)
ODI also reviewed an earlier paper by Dr. Belt suggesting a
different theory for a vehicle-based cause of SUA in Tesla
vehicles.\15\ This paper, dated May 1, 2018, was referenced in a
supplemental submission from the consumer who submitted VOQ
11206155.\16\ The SUA theory proposed by Dr. Belt in the May 2018 paper
originated from his reconstruction of accelerator position log data
from an unknown SUA incident that was described to him over the
phone.\17\ Based on this reconstruction, Dr. Belt concluded that the
APPS signal could not have been produced by the driver's application of
the accelerator pedal, as summarized below from the paper's abstract:
\18\
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\15\ Belt, Ronald. ``Tesla's Sudden Acceleration Log Data--What
It Shows.'' Center for Auto Safety, May 1, 2018. https://www.autosafety.org/wp-content/uploads/2015/03/Teslas-Sudden-Acceleration-Log-Data-What-It-Shows.pdf.
\16\ ``My Experiences with Tesla Model 3,'' p 10.
\17\ The paper provides the following explanation of how the
accelerator pedal position data was reconstructed: ``In this paper,
the author has obtained the complete accelerator pedal sensor log
data for a sudden acceleration incident from a driver who got the
log data from Tesla during a telephone conversation. The Tesla
engineer gave a detailed description of the log data to the driver,
who then provided it to the author. The author then plotted this
data to create the figure used in this study.''
\18\ Dr. Belt's reconstruction imagines the APPS log data as a
square wave, which he asserts could not have been produced by a
physical application of the accelerator pedal.
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``Examination of the data shows that the accelerator pedal sensor
output increased to cause the sudden acceleration. But the increase in
the accelerator pedal sensor output could not have been caused by the
driver. Instead, the increase in the accelerator pedal sensor output
appears to have been caused by a fault in the motor speed sensor, with
which it shares a common +5V power and ground.''
Like his June 2020 paper, the theory proposed by Dr. Belt in the
May 2018 paper is based upon inaccurate event data and false
assumptions about system design. The APPS data is not recorded in
Tesla's log data in the manner claimed in the paper (see section 3.3.5
ODI Analysis of EDR Data).\19\ In addition, circuit design information
provided to ODI by Tesla shows that Dr. Belt's assumption that ``[t]he
two accelerator pedal sensors and the motor speed sensor share the same
+5V regulator and ground,'' is incorrect. Tesla uses two distinct
regulators with different voltage outputs to supply power to the APPS
and motor speed sensors. Thus, the May 2018 paper does not provide a
valid explanation for a fault-based cause of SUA in the subject
vehicles. Based upon the reported increase in accelerator pedal
position to 97 percent shortly before collision, the most likely cause
of the incident described in the May 2018 Belt paper is pedal
misapplication by the driver.
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\19\ ODI does not believe that Dr. Belt's reconstruction of the
log data is accurate. The data log is not capable of recording a
square wave with 1 Hz sampling of the APPS data.
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3.7 Brake System
The subject vehicles are all equipped with pedal-actuated hydraulic
brake systems that are completely independent of the motor control
system. No common fault has been identified or postulated that would
cause simultaneous malfunctions of the brake and motor control systems
in the subject vehicles. Power assist is provided either electro-
mechanically or from a dedicated vacuum pump. In addition, all subject
vehicles have Tesla's brake override logic that will cut motor torque
if the brake and accelerator are applied at the same time. If the
accelerator pedal is pressed before the brake pedal (or within 100
milliseconds of brake pedal), motor torque is reduced to zero. If the
brake pedal is pressed and then the accelerator pedal, motor torque is
limited to 250 Nm and motor power is limited to 50 kW. In the latter
condition, the driver should be able to hold the vehicle stationary
regardless of accelerator pedal position with 85 to 170 N (19 to 38
lbf) of brake pedal force, depending on the platform.
Finally, the subject vehicles also contain Tesla's Pedal
Misapplication Mitigation (PMM) software which uses vehicle sensor data
to identify potential pedal misapplications and cut motor torque to
prevent or mitigate SUA
[[Page 2739]]
crashes. ODI's analysis found evidence of PMM activation in
approximately 13 percent of crashes where log data was reviewed for SUA
crashes. The effectiveness of the PMM activations have been limited by
the fact that the original PMM implementation is designed for
conditions where the vehicle is traveling straight forward or rearward
toward the collision obstacle. Most SUA crashes reviewed in this
petition evaluation involved dynamic steering inputs (i.e., vehicles
with steering angles of 180 degrees or greater when the SUA occurs)
which the original implementation of PPM was not designed to address.
3.8 Complaint Vehicle Service History Review
ODI requested service histories for the accelerator pedal
assemblies, motor control systems and brake systems for 204 of the
vehicles cited by the petitioner. Only two vehicles had faults
diagnosed in those components: One motor fault resulting in a vehicle
stall allegation and the other an APPS fault that appears to have
resulted from damage incurred by the force of the driver's foot on the
pedal during the crash event.
One of the VOQs identified by the petitioner reported feeling a
jerk forward when approaching a stop sign, then a complete loss of
power (VOQ 11164094). The data logs from the vehicle show no increase
in speed and the system cutting motor torque to zero in response to a
drive inverter fault. ODI does not consider this incident a valid
example of SUA.
Another vehicle had an accelerator pedal assembly replaced to
repair a crash induced fault in one of the pedal tracks (VOQ 11180431).
The data log shows increased drive motor torque in response to manual
application of the accelerator pedal to 88.4 percent. After the fault
in the pedal assembly was detected, motor torque was cut to zero within
0.04 seconds.
The service history analysis indicates that component faults are
not a factor in the SUA incidents reported to NHTSA. The data logs for
the two incidents that did involve component faults demonstrated that
system failsafe torque cut logic worked as designed.
5.0 Conclusion
After reviewing the available data, ODI has not identified evidence
that would support opening a defect investigation into SUA in the
subject vehicles. The evidence shows that SUA crashes in the complaints
cited by the petitioner have been caused by pedal misapplication. There
is no evidence of any fault in the accelerator pedal assemblies, motor
control systems, or brake systems that has contributed to any of the
cited incidents. There is also no evidence of a design factor
contributing to increased likelihood of pedal misapplication.
NHTSA is authorized to issue an order requiring notification and
remedy of a defect if the Agency's investigation shows a defect in
design, construction, or performance of a motor vehicle that presents
an unreasonable risk to safety. 49 U.S.C. 30102(a)(9), 30118. Given the
fact that the event data do not provide evidence that the subject SUA
was caused by a vehicle-based defect, it is unlikely that an order
concerning the notification and remedy of a safety-related defect would
be issued due to any investigation opened upon grant of this petition.
Therefore, and upon full consideration of the information presented in
the petition and the potential risks to safety, the petition is denied.
The denial of this petition does not foreclose the Agency from taking
further action if warranted or the potential for a future finding that
a safety-related defect exists based upon additional information the
Agency may receive.
Authority: 49 U.S.C. 30162(d); delegations of authority at CFR
1.95 and 501.8.
Jeffrey Mark Giuseppe,
Associate Administrator for Enforcement.
[FR Doc. 2021-00501 Filed 1-12-21; 8:45 am]
BILLING CODE 4910-59-P