# US 11,999,348 B2 · Adaptive brake mode selection

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- Number: US 11,999,348 B2
- Document ID: US11999348B2
- Status: Granted
- Kind: B2
- Application number: 16/773,541
- Filed: 2020-01-27
- Published: 2021-07-29
- Granted: 2024-06-04
- Earliest claimed: 2020-01-27
- Assignees: Tusimple, Inc.
- Applicants: Tusimple, Inc.
- Inventors: Junbo Jing; Arda Kurt; Chasen Sherman; Tianqu Shao; Haoming Sun
- Web page: https://patentgrep.com/patent/US11999348B2

## CPC

- B60W 30/18136: {Engine braking}
- B60T 7/12: for automatic initiation; for initiation not subject to will of driver or passenger {(limiting speed of vehicles other than rail vehicles B60K31/00)}
- B60T 13/662: {characterised by specified functions of the control system components}
- B60W 10/06: including control of combustion engines
- B60W 10/18: including control of braking systems
- B60W 10/184: with wheel brakes
- B60W 30/18109: {Braking}
- B60W 30/188: Controlling power parameters of the driveline, e.g. determining the required power
- B60W 30/1882: {characterised by the working point of the engine, e.g. by using engine output chart}
- B60W 60/0025: {specially adapted for specific operations}
- F02D 9/06: Exhaust brakes
- F02D 13/04: using engine as brake
- B60W 2050/0031: {Mathematical model of the vehicle}
- B60W 2050/0039: {of the propulsion unit}
- B60W 2050/0088: {Adaptive recalibration}
- B60W 2300/12: Trucks; Load vehicles
- B60W 2510/0657: Engine torque
- B60W 2510/10: Change speed gearings
- B60W 2520/10: Longitudinal speed
- B60W 2520/28: Wheel speed
- B60W 2530/10: Weight
- B60W 2530/16: Driving resistance
- B60W 2552/15: Road slope, i.e. the inclination of a road segment in the longitudinal direction
- B60W 2710/06: Combustion engines, Gas turbines
- B60W 2710/18: Braking system
- F02D 41/2451: {characterised by what is learned or calibrated}
- F02D 2200/1004: Estimation of the output torque
- F02D 2200/1006: Engine torque losses, e.g. friction or pumping losses or losses caused by external loads of accessories
- Y02T 10/40: Engine management systems
- Y02T 10/84: Data processing systems or methods, management, administration
- B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60T: VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL (electrodynamic brake systems for vehicle, in general B60L; brakes per se, i.e. devices where braking effect occurs, including ultimate brake actuators, F16D); ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Methods, systems, and devices related to a method of controlling an autonomous vehicle, in particular, an autonomous diesel-engine truck are disclosed. In one example aspect, the method includes determining an available engine brake torque generation mechanism for reducing a current speed of the autonomous vehicle to a lower speed and selecting a brake mode corresponding to the engine brake torque availability. In case a rate of speed reduction is equal to or smaller than a threshold, the brake mode includes only an engine brake in which engine exhaust valve opening is adjusted for reducing the current speed. The threshold determined in part based on the available engine brake torque, gear position of the transmission, and the online estimated vehicle longitudinal dynamic model. In case the rate of speed reduction is greater than the threshold, the brake mode incudes a combination of the engine brake and the foundation brake.

## Claims

### Claim 1

A method of controlling a diesel-engine autonomous vehicle, comprising:
determining, using an adaptive model of the autonomous vehicle that adaptively adjusts model parameters while the autonomous vehicle is in operation:
(i) longitudinal dynamic response properties of the autonomous vehicle that indicate a dynamic response of the autonomous vehicle to longitudinal forces, and
(ii) an available engine brake torque for reducing a current speed of the autonomous vehicle to a lower speed,
wherein the adaptive model adaptively adjusts the model parameters for the determining the longitudinal dynamic response properties and the available engine brake torque by an online linear regression method that approximates a time-variant or high-order system by a time-invariant or a low-order model; and
selecting a brake mode corresponding to the available engine brake torque and a rate of speed reduction,
wherein, in case that the rate of speed reduction is equal to or smaller than a threshold, the brake mode is an engine brake in which engine exhaust valve opening is adjusted to generate a brake torque for reducing the current speed, the threshold determined in part based on the available engine brake torque and the longitudinal dynamic response properties of the autonomous vehicle, and
wherein the brake mode is a combination of the engine brake and a foundation brake in case the rate of speed reduction is greater than the threshold.

### Claim 2 (depends on 1)

The method of claim 1, comprising:
receiving a deceleration request for reducing the current speed of the autonomous vehicle to the lower speed; and
converting, based on measurements of the autonomous vehicle, the deceleration request to a request with respect to an engine brake torque.

### Claim 3 (depends on 2)

The method of claim 2, wherein converting the deceleration request comprises:
determining the engine brake torque by generating an engine brake torque capacity model.

### Claim 4 (depends on 3)

The method of claim 3, wherein the engine brake torque capacity model is generated based on data collected when an adjustment of the engine exhaust valve opening is electronically requested.

### Claim 5 (depends on 2)

The method of claim 2, wherein converting the deceleration request comprises:
generating an exhaust valve opening model to approximate the available engine brake torque.

### Claim 6 (depends on 2)

The method of claim 2, wherein the deceleration request is converted based on a longitudinal dynamic model of the autonomous vehicle that is generated based on at least an engine torque or a vehicle wheel speed.

### Claim 7 (depends on 1)

The method of claim 1, wherein the adaptive model uses model parameters that are modified based on a cost function during operation of the autonomous vehicle.

### Claim 8

An autonomous vehicle, comprising:
a monitor system configured to measure vehicle states of the autonomous vehicle,
a transmission system, and
a control system in communication with the transmission system and in communication with the monitor system to receive the measured vehicle states, the control system including a processor that is configured to:
determine, using an adaptive model of the autonomous vehicle that adaptively adjusts model parameters while the autonomous vehicle is in operation, an available engine brake torque for reducing a current speed of the autonomous vehicle to a lower speed,
wherein the adaptive model adaptively adjusts the model parameters for the determining the available engine brake torque by an online linear regression method that approximates a time-variant or high-order system by a time-invariant or a low-order model, and
wherein the model parameters of the adaptive model are modified during operation of the autonomous vehicle based on a cost function, the cost function comprising a factor indicating a length of time in which parameters of the autonomous vehicle stay invariant; and
select a brake mode corresponding to the available engine brake torque and a rate of speed reduction,
wherein, in case that the rate of speed reduction is equal to or smaller than a threshold, the brake mode is an engine brake in which engine exhaust valve opening is adjusted to generate a brake torque for reducing the current speed, the threshold determined in part based on the available engine brake torque, and
wherein the brake mode includes a combination of the engine brake and a foundation brake in case the rate of speed reduction is greater than the threshold; and
generate the brake torque when the transmission system is not engaged in a gear shift, wherein the rate of speed reduction is converted to the generated brake torque based on the parameters of the autonomous vehicle that stay invariant over the length of time.

### Claim 9 (depends on 8)

The vehicle of claim 8, wherein the processor is further configured to:
approximate the available engine brake torque based on an exhaust valve opening model.

### Claim 10 (depends on 9)

The vehicle of claim 9, wherein the exhaust valve opening model is generated based on empirical fitting of data from one or more exhaust valves.

### Claim 11

A non-transitory computer readable storage medium, storing computer readable instructions configured to perform a method that comprises:
determining, using an adaptive model of an autonomous vehicle that adaptively adjusts model parameters while the autonomous vehicle is in operation:
(i) longitudinal dynamic response properties of the autonomous vehicle that indicate a dynamic response of the autonomous vehicle to longitudinal forces, and
(ii) an available engine brake torque for reducing a current speed of the autonomous vehicle to a lower speed,
wherein the adaptive model adaptively adjusts the model parameters for the determining the longitudinal dynamic response properties and the available engine brake torque by an online linear regression method that approximates a time-variant or high-order system by a time-invariant or a low-order model; and
selecting a brake mode corresponding to the available engine brake torque and a rate of speed reduction,
wherein, in case that the rate of speed reduction is equal to or smaller than a threshold, the brake mode is an engine brake in which engine exhaust valve opening is adjusted to generate a brake torque for reducing the current speed, the threshold determined in part based on the available engine brake torque and the longitudinal dynamic response properties of the autonomous vehicle, and
wherein the brake mode is a combination of the engine brake and a foundation brake in case the rate of speed reduction is greater than the threshold.

### Claim 12 (depends on 11)

The non-transitory computer readable storage medium of claim 11, wherein the method comprises:
converting, based on measurements of the autonomous vehicle, a deceleration request for reducing the current speed of the autonomous vehicle to the lower speed to a request with respect to an engine brake torque.

### Claim 13 (depends on 12)

The non-transitory computer readable storage medium of claim 12, wherein the engine brake torque is associated with at least a driving speed or a powertrain state.

### Claim 14 (depends on 12)

The non-transitory computer readable storage medium of claim 12, wherein the deceleration request is converted based on a longitudinal dynamic model of the autonomous vehicle.

### Claim 15 (depends on 14)

The non-transitory computer readable storage medium of claim 14, wherein the longitudinal dynamic model is implemented using online adaptive parameters of the autonomous vehicle.

### Claim 16 (depends on 11)

The non-transitory computer readable storage medium of claim 11, wherein the adaptive model uses model parameters that are modified during operation of the autonomous vehicle based on a Recursive Least Square method.

### Claim 17 (depends on 16)

The non-transitory computer readable storage medium of claim 16, wherein an Exponential Weighted Moving Average (EWMA) filter is applied to an error of the Recursive Least Square method for adaptation reset triggering.