Tesla Motors Club

Since I know we have a lot of discussions about the SAE levels, I thought I would write up a primer from the SAE document:

General

• The levels are not in order of quality, or merit or technology. L5 is not necessarily “better” than L4. L4 is not necessarily “better” than L3.
• A “high functioning” L3 does not become a “low functioning” or “partial” L4. It is still L3.
• SAE levels are never fractions. For example, if a system qualifies as L3 system, it is L3, not L3.5 or L3.7.
• The SAE levels are discrete and mutually exclusive. So a system or feature cannot be both L3 and L4. It is one or the other.
• It is possible for a car to have different features of different levels. For example, our Teslas have TACC which is L1 and AP which is L2. When AP is on, our cars operate at L2 and when TACC is on, they operate at L1.
• The SAE does not expect autonomous driving systems to do strategic tasks like trip planning or scheduling that are typically done before starting a trip. The SAE levels only expect the autonomous driving to perform dynamic driving tasks (DDT) which are the driving tasks performed during the actual driving part.
• The SAE levels are defined based on the role that the human and the automated driving system have during a trip.
• Active safety systems like automatic emergency braking or emergency lane departure avoidance can be included on cars of any levels.
• Individual features can have a level of autonomy. For example, auto park with no driver inside could be a L4 feature.

Monitoring human attention

• Only L2 and L3 need to monitor the human since L2 needs the human to be an attentive driver and L3 may need the human to intervene.
• L4 and L5 do not need to monitor human attention since the systems are capable of pulling over in case of a problem on their own.

Monitoring vehicle and system failure

• L3, L4 and L5 need to be able to self-monitor their systems for any problems.
• For L1 and L2, the human is expected to monitor the vehicle and system for any problems.

Object, Event, Detection, Response (OEDR)

• A sub task of DDT that involves detecting, recognizing, and classifying objects and events, preparing a response and executing a response. Example: seeing a stop sign and stopping in time.
• If the system can do entire OEDR in its ODD, then it is L3-L5 autonomous, If it cannot do entire OEDR, then it is a “driver assist” (L1-L2).

Operational Design Domain (ODD)

• The conditions that an automated driving system can operate in. Conditions include environmental, geographical, time of day restrictions, presence of absence of traffic or roadway characteristics.
• If the ODD has special restrictions due to technological limits, then it is L3/L4. For example, limited to low speeds or limited to only highways because the automated driving system cannot operate safely outside those limits.
• L5 ODD is defined as all driver-managebale road conditions within its region of the world. For example, L5 is not expected to operate in flooded roads, or white out snow storms.
• Non technological limits to the ODD don’t count. For example, an autonomous vehicle that could operate in Canada but is geofenced to the US due to legal reasons, would still be considered L5.
• Example of L5 ODD: a robotaxi that can operate on all driver manageable roads in the US, day or night, all weather that human can handle, all legal speeds.

Receptivity of human

• L0-L2, the human is expected to fully receptive to what is going on.
• L3, the human should be receptive to a vehicle failure or the system requesting intervention.

Supervision of driving automation system

• For L1 or L2, the human is expected to supervise the system.

Sustained operation

• The SAE levels require that the driving feature be sustainable, meaning that they must be able to continue functioning across external events. Example, adaptive cruise control counts because it can change the speed based on change in speed of the front car. But dumb cruise control does not count as sustained operation since it cannot reacting to change in front car’s speed.

Usage specification

• The SAE level for a particular ODD.
• Since L3 or L4 system can have different limited ODD, it is necessary to specify both the SAE level and the ODD in order to fully describe the capabilities of a L3 or L4 system or feature.
• Since L5 has all encompassing ODD, it is not necessary to specify ODD for L5.

Level 0: No automation

• Driving Automation System (if any): Does not perform any part of the DDT on a sustained basis (although other vehicle systems may provide warnings or support, such as momentary emergency intervention).
• Human (at all times): Performs the entire DDT
• For levels 1-2, the automated driving system performs only part of the DDT.

For level 1-2, the driver automated system only performs part of the DDT

Level 1: Driver Assist

• Driving Automation System (while engaged): Performs part of the DDT by executing either the longitudinal or the lateral vehicle motion control subtask. Disengages immediately upon driver request
• Human (at all times): Performs the remainder of the DDT not performed by the driving automation system. Supervises the driving automation system and intervenes as necessary to maintain safe operation of the vehicle. Determines whether/when engagement or disengagement of the driving automation system is appropriate. Immediately performs the entire DDT whenever required or desired.

Level 2: partial driving automation

• Driving Automation System (while engaged): Performs part of the DDT by executing both the lateral and the longitudinal vehicle motion control subtasks. Disengages immediately upon driver request.
• Human (at all times): Performs the remainder of the DDT not performed by the driving automation system. Supervises the driving automation system and intervenes as necessary to maintain safe operation of the vehicle. Determines whether/when engagement and disengagement of the driving automation system is appropriate. Immediately performs the entire DDT whenever required or desired.
• L2 can bring the car to a controlled stop in the middle of the lane if the driver fails to supervise the feature. For example, AP does this now when it comes to a controlled stop if we ignore the nags long enough.

For levels 3-5, the automated driving system performs the entire DDT.

Level 3: conditional driving automation

• ADS (while not engaged): Permits engagement only within its ODD
• ADS (while engaged): Performs the entire DDT. Determines whether ODD limits are about to be exceeded and, if so, issues a timely request to the human to intervene. Determines whether there is a DDT performance-relevant system failure of the ADS and, if so, issues a timely request to the human to intervene. Disengages an appropriate time after issuing a request to intervene. Disengages immediately upon driver request
• Human (while the ADS is not engaged): Verifies operational readiness of the ADS-equipped vehicle. Determines when engagement of ADS is appropriate. Becomes the DDT fallback-ready user when the ADS is engaged
• Human (while the ADS is engaged): Is receptive to a request to intervene and responds by performing DDT fallback in a timely manner. Is receptive to DDT performance-relevant system failures in vehicle systems and, upon occurrence, performs DDT fallback in a timely manner. Determines whether and how to achieve a minimal risk condition. Becomes the driver upon requesting disengagement of the ADS
• L3 can bring the car to a controlled stop in the middle of the lane if the driver fails to take over when prompted.

Examples of L3 fallback:

• L3 system is engaged and experiences a vehicle failure (ie flat tire). The human recognizes failure and takes over and pulls the car over to the side of the road.
• L3 system is engaged and experiences a system failure (ie sensors are obstructed). The L3 system notifies the human who takes over and resumes manual driving.
• L3 system is engaged but is about to leave the conditions that it can operate in (for ex: leaving the highway). It notifies the human who takes over and resumes manual driving.

Level 4: High driving automation

• ADS (while not engaged): Permits engagement only within its ODD
• ADS (while engaged): Performs the entire DDT. May issue a timely request to intervene. Performs DDT fallback and transitions automatically to a minimal risk condition when: A DDT performance-relevant system failure occurs or a user does not respond to a request to intervene or a user requests that it achieve a minimal risk condition. Disengages, if appropriate, only after: it achieves a minimal risk condition or a driver is performing the DDT. May delay user-requested disengagement.
• Driver/dispatcher (while the ADS is not engaged): Verifies operational readiness of the ADS-equipped vehicle. Determines whether to engage the ADS. Becomes a passenger when the ADS is engaged only if physically present in the vehicle.
• Passenger/dispatcher (while the ADS is engaged): Need not perform the DDT or DDT fallback. Need not determine whether and how to achieve a minimal risk condition. May perform the DDT fallback following a request to intervene. May request that the ADS disengage and may achieve a minimal risk condition after it is disengaged. May become the driver after a requested disengagement.
• In a emergency like a total loss of power that would not give the car enough time to pull over, L4 can bring the car to a controlled stop in the lane.

Level 5: Full driving automation

• ADS (while not engaged): Permits engagement of the ADS under all driver-manageable on-road conditions
• ADS (while engaged): Performs the entire DDT. Performs DDT fallback and transitions automatically to a minimal risk condition when: a DDT performance-relevant system failure occurs or a user does not respond to a request to intervene or a user requests that it achieve a minimal risk condition. Disengages, if appropriate, only after: It achieves a minimal risk condition or a driver is performing the DDT. May delay a user-requested disengagement
• Driver/dispatcher (while the ADS is not engaged): Verifies operational readiness of the ADS-equipped vehicle. Determines whether to engage the ADS. Becomes a passenger when the ADS is engaged only if physically present in the vehicle
• Passenger/dispatcher (while the ADS is engaged): Need not perform the DDT or DDT fallback. Need not determine whether and how to achieve a minimal risk condition. May perform the DDT fallback following a request to intervene. May request that the ADS disengage and may achieve a minimal risk condition after it is disengaged. May become the driver after a requested disengagement.
• In an emergency like a total loss of power that would not give the car enough time to pull over, L5 can bring the car to a controlled stop in the lane.

Hope this helps.