CN113049846A

CN113049846A - System and method for measuring trailer wheel speed

Info

Publication number: CN113049846A
Application number: CN202011577602.5A
Authority: CN
Inventors: B.皮策
Original assignee: Waymo LLC
Current assignee: Waymo LLC
Priority date: 2019-12-27
Filing date: 2020-12-28
Publication date: 2021-06-29
Anticipated expiration: 2040-12-28
Also published as: CN113049846B

Abstract

Example embodiments relate to measuring the rotational speed of trailer wheels using radar. The computing device may cause the vehicle radar unit to transmit radar signals toward wheels of a trailer being pulled by the vehicle. The computing device may receive radar reflections corresponding to radar signals reflected from the wheel and determine a rotational speed of the wheel based on the radar reflections. For example, the computing device may identify the highest or lowest frequency in the spectrum of radar reflections and use that frequency and the radius of the wheel to calculate the rotational speed of the wheel. The computing device may use the rotational speed measurements of the trailer wheels to monitor the performance of the trailer and adjust the vehicle navigation accordingly. In some cases, the computing device may determine that one of the trailer wheels requires maintenance based on monitoring the rotational speed of the trailer wheels.

Description

System and method for measuring trailer wheel speed

Cross Reference to Related Applications

The present disclosure claims priority from U.S. provisional application No.62/954,080 filed on 27.12.2019, the entire contents of which are incorporated herein by reference.

Background

Radio detection and ranging systems ("radar systems") are used to estimate the distance to environmental features by transmitting radio signals and detecting the returned reflected signals. The distance to radio reflection features in the environment can then be determined from the time delay between transmission and reception. The radar system may transmit a time-varying frequency signal, such as a signal having a time-varying frequency ramp, and then correlate the frequency difference between the transmitted signal and the reflected signal with a range estimate. Some radar systems may also estimate the relative motion of reflective objects based on doppler frequency shifts in the received reflected signals.

Directional antennas may be used for transmission and/or reception of signals to associate each range estimate with a bearing (bearing). More generally, directional antennas may also be used to focus radiated energy on a given field of view of interest. Combining the measured distance and orientation information may allow mapping of ambient features.

Disclosure of Invention

Example embodiments relate to techniques for measuring rotational speed of trailer wheels using a radar or another type of sensor coupled to a vehicle towing the trailer. By determining the rotational speed of the trailer wheels, the system can monitor the health and operation of the trailer wheels, which can be used to increase safety during navigation.

Thus, the first example embodiment describes a system. The system includes a radar unit coupled to the vehicle. The vehicle is towing a trailer and the radar unit has a field of view that includes the wheels of the trailer. The system also includes a computing device. The computing device is configured to cause the radar unit to transmit a radar signal toward the wheel and receive a radar reflection corresponding to the radar signal reflected from the wheel. The computing device is further configured to determine a rotational speed of the wheel based on the radar reflection.

Another example embodiment describes a method. The method involves causing, by a computing device coupled to the vehicle, a radar unit to transmit a radar signal toward wheels of the trailer. The trailer is coupled to the vehicle, and the radar unit has a field of view that includes wheels. The method also involves receiving radar reflections corresponding to the radar signals reflected from the wheel and determining a rotational speed of the wheel based on the radar reflections.

Additional example embodiments describe a non-transitory computer-readable medium configured to store instructions that, when executed by a computing system, cause the computing system to perform the operations of the above-described method.

The fourth embodiment may be directed to a system including various means for performing each of the operations of the first, second, and third embodiments.

These and other embodiments, aspects, advantages, and alternatives will become apparent to one of ordinary skill in the art by reading the following detailed description, where appropriate, with reference to the accompanying drawings. In addition, it is to be understood that the summary of the invention provided herein, as well as other descriptions and drawings, are intended to illustrate embodiments by way of example only and that numerous variations are possible. For example, structural elements and process steps may be rearranged, combined, distributed, eliminated, or otherwise altered while remaining within the scope of the embodiments.

Drawings

FIG. 1 is a functional block diagram illustrating a vehicle in accordance with one or more example embodiments.

FIG. 2A illustrates a front view of a vehicle in accordance with one or more example embodiments.

FIG. 2B illustrates a side view of a vehicle in accordance with one or more example embodiments.

FIG. 2C illustrates a perspective view of a vehicle in accordance with one or more example embodiments.

Fig. 2D illustrates a top view of a vehicle in accordance with one or more example embodiments.

FIG. 3 illustrates fields of view of various sensors in accordance with one or more example embodiments.

Fig. 4 illustrates beam steering for a sensor in accordance with one or more example embodiments.

FIG. 5 illustrates a sensor measuring wheel speed in accordance with one or more example embodiments.

FIG. 6 is a flow diagram of a method for measuring wheel speed according to one or more examples.

FIG. 7 is another flow diagram of a method for measuring rotational speed of trailer wheels using radar, according to one or more example embodiments.

Fig. 8 illustrates a schematic diagram of a computer program according to an example embodiment.

Detailed Description

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, like numerals generally identify like components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

Radar systems use radar units to capture measurements of the surrounding environment. In particular, the radar unit may transmit (i.e., transmit) radar signals in a predetermined direction using the transmit antenna to measure aspects of that direction of the environment. Upon contact with a surface in the environment, the transmitted radar signals are scattered in multiple directions, with some of the radar signals penetrating the surface and another portion of the radar signals being reflected from the surface towards a receiving antenna on the radar unit (or another radar unit) where the reflections may be captured. The received reflected signals are then processed by a radar processing system to determine two-dimensional (2D) or three-dimensional (3D) measurements of the environment, including the position, orientation, and movement of various nearby surfaces. The radar system may include one or more radar processing systems configured to process incoming radar reflections received at the respective radar units.

Radar systems are increasingly used in vehicle navigation and safety systems because they can measure the distance and movement of objects and other surfaces in an environment. For example, vehicle radar systems may capture measurements of the surroundings of a vehicle, which may be used to detect and help identify nearby vehicles, road boundaries, weather conditions (e.g., wet or snowy roads), traffic signs and signals, and pedestrians, as well as other features in the surrounding environment. Thus, vehicle navigation systems often use radar measurements when formulating control strategies for autonomous or semi-autonomous navigation.

In practice, vehicle radar systems for automobiles or similar types of vehicles often have radar units coupled at various external locations, such as on side mirrors, bumpers, roofs, front grilles, doors, or side panels of the vehicle. These locations are often selected for mounting radar units such that a collection of radar units can capture measurements of the surrounding environment and mounting radar units on these exterior portions does not require redesign and special manufacturing of the vehicle. Furthermore, the radar unit coupled at an external location can be easily adjusted for calibration purposes.

While vehicle radars are commonly used to measure various aspects of the vehicle surroundings, vehicle radars may also be used to otherwise enhance the operation of the vehicle. Example embodiments presented herein relate to using a vehicle radar to determine the rotational speed of trailer wheels. A semi-truck or another type of vehicle towing a trailer may use radar or other sensors to determine the rotational speed of the trailer wheels during navigation. By monitoring the rotational speed of the trailer wheels, the vehicle system can quickly identify when the trailer wheels cease normal operation and enable the vehicle to respond accordingly. For example, the vehicle may gradually come to a stop in a safe area in response to detecting that one or more trailer wheels are not rotating at a given rotational speed that matches other trailer wheels. In some cases, monitoring the rotational speed of the trailer wheels may help enhance safety during navigation. For example, the vehicle may adjust the turning radius or speed based on the rotational speed of the trailer wheels. As such, the rotational speed may be indicative of the current health and operation of the tires and help ensure that the trailer is functioning properly during towing.

Various types of vehicles may use the sensor arrangements and sensor data processing techniques described herein. Example vehicles include, but are not limited to, semi-trucks, tractors, Sport Utility Vehicles (SUVs), and vans, among others. Example trailers may include, but are not limited to, flatbeds, enclosed trailers, refrigerated trailers, multi-car trailers, and special trailers. Furthermore, the trailer may also correspond to another type of structure, such as a mobile house or another vehicle being towed.

For the purpose of illustrating an example, a semi-truck is a vehicle designed to tow a trailer. To enhance the operation of the semi-truck, one or more sensor systems may be strategically placed on the tractor unit to enable the tractor unit to use the sensor data regardless of which trailer (if any) is connected. As such, a computing device on the semi-truck may cause the radar unit to transmit radar signals toward the trailer wheels and receive radar reflections corresponding to the radar signals reflected from the wheels. The computing device may use the frequency of the radar reflection and the radius (or diameter) of the trailer wheel to calculate the current rotational speed of the trailer wheel. The computing device may monitor trailer wheel speeds to increase safety during navigation and identify potential problems that may arise when one or more trailer wheels cease normal operation. The rotational speed of the trailer wheels may be determined as Revolutions Per Minute (RPM) or otherwise quantified within examples. In some cases, the tire may be embedded with a steel band that may enhance sensor measurements (e.g., radar reflection).

As indicated above, radar may be used to measure the speed of objects traveling towards and/or away from the sensor. As such, a radar unit coupled to a vehicle towing a trailer may be directed directly at a tire rotating on the trailer to observe an upper portion of the tire moving in one direction (e.g., moving toward the sensor) and a lower portion of the tire moving in another direction (e.g., moving away from the sensor) at the same speed. The observed velocity decreases as the measurement is captured closer to the center of the tire. Thus, a radar unit having a sufficiently large field of view to observe a sufficiently large portion of the tire (e.g., the entire tire) may capture a measurement of the maximum observed speed (positive or negative), enabling the processing unit to assume that this portion of the tire may correspond to an outer portion of the wheel (e.g., adjacent the circumference) to calculate the rotational speed ω using the wheel radius r, as follows:

in some embodiments, the system may measure rotational speed using one or more sensors by comparing the frequency spectrum returned in the measurement of the trailer wheels. For example, short radar pulses (e.g., 500MHz) may be reflected and slightly distorted by the tire. The portion of the tire that rotates toward the sensor may cause a doppler shift to a higher frequency and the backward portion may cause a corresponding doppler shift to a lower frequency. The result of these doppler shifts can produce the spectral response of the radar pulse. As such, the processing unit may select and use the highest or lowest frequency of the trailer wheels and the radius to calculate the current rotational speed of the trailer wheels using the above equation.

By measuring the rotational speed of multiple wheels, the system can detect and predict potential performance problems. For example, the system may compare the speed of the trailer and/or the wheels of the vehicle to identify a difference, which may indicate that the vehicle or trailer is experiencing a potential problem. In some cases, the variance in wheel speed between multiple wheels that exceed a threshold difference may indicate a problem, such as tire deflation, tire spoke damage, or some other complication.

In some embodiments, the vehicle system may also compare the current rotational speed of the trailer wheels to one or more reference wheel speeds. The reference rotational speed of the trailer wheels, also referred to herein as the expected wheel speed, may represent the desired rotational speed of the wheels to be rotated based on the current operation of the vehicle (e.g., speed, heading, and grade traveled) and possibly other factors (e.g., weight of cargo carried by the trailer).

As discussed above, the reference wheel speed may be based on sensor measurements of one or more other wheels associated with the vehicle and/or trailer. For example, a reference wheel speed used to analyze the wheel speed of the trailer may be based on wheel speed measurements obtained from wheels of the trailer (e.g., wheels on a tractor unit). In some cases, the reference wheel speed may be based on one or more recorded wheel speeds. For example, the system may use periodic measurements of wheel speed to ensure that the wheels are operating as desired.

To further illustrate, the system may compare a current wheel speed measurement determined using a sensor measurement (e.g., radar) to a past measurement when the vehicle is navigating under similar conditions. A similar situation may be where the vehicle is traveling at a similar speed (e.g., 60 miles per hour) on a similar path (e.g., the same grade and heading). The system may take into account additional parameters when analyzing the wheel speeds of the vehicle and trailer. For example, the system may obtain measurements (e.g., angles from steering sensors) from an Inertial Measurement Unit (IMU) and/or other sensors of the vehicle to determine the current speed and heading at which the vehicle is traveling.

In some embodiments, the system may take into account navigation parameters as the navigation of the vehicle may affect the desire for wheel speed. For example, when the vehicle is navigating a straight path, it may be desirable for the speed of the wheels of the cab portion to be equal to the speed of the wheels of the trailer portion. Thus, if the system detects a large discrepancy between the vehicle wheel speed and the trailer wheel speed, the system may determine that there is some problem (e.g., a flat or blown tire, a damaged tire spoke or axle, a sensor error) and perform a corrective action (e.g., perform an emergency stop procedure).

During navigation, the system may monitor wheel speeds of one or more wheels during various types of vehicle movement, including during cornering or brake application. By monitoring the measured wheel speeds, the system may be able to determine whether the brakes are functioning properly, e.g., the brakes are locked or not engaged properly. If the brakes do not function properly, the control system may be able to modulate the application of the brakes to prevent deadlock. In other examples, if the brakes are not properly engaged, the vehicle may activate a backup braking system or implement another strategy (e.g., an emergency stop procedure).

In another example, the system may be capable of monitoring a controlled reduction of the trailer, such as slip, based on the measured wheel speeds. The control system may be capable of adjusting a control scheme or maneuver of the vehicle in response to a loss of control. The system may also monitor the speed of the trailer wheels during turns or other challenging navigational movements. In some examples, the system may continuously monitor the wheel speed of the trailer. In other examples, the system may use map data and/or other sensor information to determine when to check the wheel speed of one or more wheels of the trailer.

Some trailers may have the ability to adjust the position of the wheels on the trailer based on the total load weight and/or weight distribution on the trailer. As such, the wheel speeds measured for the trailer wheels may be used to adjust the position of the wheels on the trailer to a position that may increase navigation capacity and efficiency.

In some embodiments, the radar system may be capable of determining radar reflections associated with one or more wheels of the trailer. The radar system may use range, angle, and doppler measurements to identify radar reflections associated with different wheels. The radar system may then be able to filter wheel reflections from the radar reflection signals to reduce noise in the received radar signals.

Some example radar systems may be configured to operate at electromagnetic wave frequencies in the W-band, which may be, for example, between 75 and 82 gigahertz (GHz), which corresponds to electromagnetic waves on the order of millimeters (e.g., 1mm, 4 mm). Radar systems may use antennas that can focus radiated energy into a beam (light beam) in order to measure the environment with high accuracy. Such antennas may be compact (typically having a rectangular form factor), efficient (i.e., heat lost in the antenna or reflected back to less 77GHz of energy in the transmitter electronics), low cost, and easy to manufacture (i.e., radar systems with these antennas may be produced in large quantities).

Referring now to the drawings, FIG. 1 is a functional block diagram illustrating an example vehicle 100, which example vehicle 100 may be configured to operate in an autonomous mode, in whole or in part. More specifically, by receiving control instructions from a computing system (e.g., a vehicle control system), the vehicle 100 may operate in an autonomous mode without human interaction (or reduced human interaction). As part of operating in the autonomous mode, the vehicle 100 may use sensors to detect and possibly identify objects of the surrounding environment in order to enable safe navigation. In some embodiments, the vehicle 100 may also include subsystems that enable a driver (or remote operator) to control the operation of the vehicle 100.

As shown in fig. 1, the vehicle 100 includes various subsystems, such as a propulsion system 102, a sensor system 104, a control system 106, one or more peripherals 108, a power source 110, a computer system 112, a data storage device 114, and a user interface 116. In other examples, vehicle 100 may include more or fewer subsystems. The subsystems and components of the vehicle 100 may be interconnected in various ways (e.g., wired or wireless connections). Further, the functionality of the vehicle 100 described herein may be divided among additional functional or physical components, or combined into fewer functional or physical components in an embodiment.

The propulsion system 102 may include one or more components operable to provide powered motion to the vehicle 100, and may include an engine/motor 118, an energy source 119, a transmission 120, and wheels/tires 121, among other possible components. For example, the engine/motor 118 may be configured to convert the energy source 119 into mechanical energy, and may correspond to one or a combination of an internal combustion engine, an electric motor, a steam engine, or a Sterling engine, among other possible options. For example, in some embodiments, the propulsion system 102 may include multiple types of engines and/or motors, such as gasoline engines and electric motors.

Energy source 119 represents a source of energy that may wholly or partially power one or more systems of vehicle 100 (e.g., engine/motor 118). For example, the energy source 119 may correspond to gasoline, diesel, other petroleum-based fuels, propane, other compressed gas-based fuels, ethanol, solar panels, batteries, and/or other sources of electrical power. In some embodiments, the energy source 119 may include a combination of a fuel tank, a battery, a capacitor, and/or a flywheel.

The transmission 120 may transmit mechanical power from the engine/motor 118 to the wheels/tires 121 and/or other possible systems of the vehicle 100. As such, the transmission 120 may include, among other possible components, a gearbox, clutches, a differential, and a driveshaft. The drive shaft may comprise a shaft connected to one or more wheels/tires 121.

The wheels/tires 121 of the vehicle 100 may have various configurations in example embodiments. For example, the vehicle 100 may exist in the form of a unicycle, bicycle/motorcycle, tricycle, or car/truck four-wheel, among other possible configurations. As such, the wheel/tire 121 may be connected to the vehicle 100 in various ways and may exist in different materials (such as metal and rubber).

The sensor system 104 may include various types of sensors, such as a Global Positioning System (GPS)122, an Inertial Measurement Unit (IMU)124, a radar unit 126, a laser range finder/LIDAR unit 128, a camera 130, a steering sensor 123, and a throttle/brake sensor 125, among other possible sensors. In some embodiments, the sensor system 104 may also include sensors (e.g., O) configured to monitor internal systems of the vehicle 100₂Monitor, fuel gauge, engine oil temperature, brake condition).

The GPS 122 may include a transceiver operable to provide information regarding the position of the vehicle 100 relative to the earth. The IMU 124 may have a configuration that uses one or more accelerometers and/or gyroscopes, and may sense position and orientation changes of the vehicle 100 based on inertial acceleration. For example, the IMU 124 may detect pitch and yaw of the vehicle 100 while the vehicle 100 is stationary or in motion.

Radar unit 126 may represent one or more systems configured to use radio signals to sense objects within the local environment of vehicle 100, including the speed and heading of the objects. As such, radar unit 126 may include an antenna configured to transmit and receive radar signals as discussed above. In some embodiments, radar unit 126 may correspond to an installable radar system configured to obtain measurements of the surroundings of vehicle 100. For example, radar unit 126 may include one or more radar units configured to be coupled to an underbody of a vehicle.

The laser rangefinder/LIDAR 128 may include one or more laser sources, a laser scanner, and one or more detectors, among other system components, and may operate in a coherent mode (e.g., using heterodyne detection) or in a non-coherent detection mode. The camera 130 may include one or more devices (e.g., still or video cameras) configured to capture images of the environment of the vehicle 100.

The steering sensor 123 may sense a steering angle of the vehicle 100, which may involve measuring an angle of a steering wheel or measuring an electrical signal representative of the angle of the steering wheel. In some embodiments, the steering sensor 123 may measure an angle of a wheel of the vehicle 100, such as detecting an angle of the wheel relative to a front axle of the vehicle 100. The steering sensor 123 may also be configured to measure a combination (or subset) of the angle of the steering wheel, an electrical signal representative of the angle of the steering wheel, and the angle of the wheels of the vehicle 100.

The throttle/brake sensor 125 may detect the position of either the throttle position or the brake position of the vehicle 100. For example, the throttle/brake sensor 125 may measure an angle of both an accelerator pedal (throttle) and a brake pedal, or may measure an electrical signal that may represent, for example, an angle of the accelerator pedal (throttle) and/or an angle of the brake pedal. The throttle/brake sensor 125 may also measure an angle of a throttle body of the vehicle 100, which may include a portion of a physical mechanism (e.g., a butterfly valve or a carburetor) that provides modulation of the energy source 119 to the engine/motor 118. Further, the throttle/brake sensor 125 may measure the pressure of one or more brake pads on the rotor of the vehicle 100 or a combination (or subset) of the accelerator pedal (throttle) and brake pedal angle, an electrical signal representing the accelerator pedal (throttle) and brake pedal angle, the angle of the throttle body, and the pressure applied by at least one brake pad to the rotor of the vehicle 100. In other embodiments, the throttle/brake sensor 125 may be configured to measure pressure applied to a pedal of the vehicle (such as a throttle or brake pedal).

The control system 106 may include components configured to assist in navigating the vehicle 100, such as a steering unit 132, a throttle 134, a brake unit 136, a sensor fusion algorithm 138, a computer vision system 140, a navigation/routing system 142, and an obstacle avoidance system 144. More specifically, the steering unit 132 may be operable to adjust the heading of the vehicle 100, and the throttle 134 may control the operating speed of the engine/motor 118 to control the acceleration of the vehicle 100. The brake unit 136 may decelerate the vehicle 100, which may involve using friction to decelerate the wheels/tires 121. In some embodiments, the brake unit 136 may convert the kinetic energy of the wheels/tires 121 into electrical current for subsequent use by one or more systems of the vehicle 100.

The sensor fusion algorithm 138 may include a Kalman filter, a Bayesian network, or other algorithm that may process data from the sensor system 104. In some implementations, the sensor fusion algorithm 138 can provide an assessment based on incoming sensor data, such as an assessment of various objects and/or features, an assessment of a particular situation, and/or an assessment of potential impact within a given situation.

The computer vision system 140 may include hardware and software operable to process and analyze images in an effort to determine objects, environmental objects (e.g., stop lights, road boundaries, etc.), and obstacles. As such, the computer vision system 140 may identify objects, map environments, track objects, estimate the speed of objects, and so forth using, for example, object recognition, Motion recovery Structure (SFM), video tracking, and other algorithms used in computer vision.

The navigation/path system 142 may determine a driving path of the vehicle 100, which may involve dynamically adjusting navigation during operation. As such, the navigation/routing system 142 may use data from the sensor fusion algorithm 138, the GPS 122, and maps, among other sources, to navigate the vehicle 100. The obstacle avoidance system 144 may evaluate potential obstacles based on the sensor data and cause systems of the vehicle 100 to avoid or otherwise handle the potential obstacles.

As shown in fig. 1, the vehicle 100 may also include peripherals 108, such as a wireless communication system 146, a touch screen 148, a microphone 150, and/or a speaker 152. Peripheral device 108 may provide controls or other elements for a user to interact with user interface 116. For example, the touch screen 148 may provide information to a user of the vehicle 100. The user interface 116 may also accept input from a user via the touch screen 148. The peripheral devices 108 may also enable the vehicle 100 to communicate with devices such as other vehicle devices.

The wireless communication system 146 may communicate wirelessly with one or more devices directly or via a communication network. For example, the wireless communication system 146 may use 3G cellular communication (such as CDMA, EVDO, GSM/GPRS), or 4G cellular communication (such as WiMAX or LTE). Alternatively, the wireless communication system 146 may communicate with a Wireless Local Area Network (WLAN) using WiFi or other possible connections. The wireless communication system 146 may also communicate directly with the devices, for example using an infrared link, bluetooth, or ZigBee. Other wireless protocols, such as various vehicle communication systems, are also possible within the context of this disclosure. For example, the wireless communication system 146 may include one or more dedicated short-range communication (DSRC) devices, which may include public and/or private data communications between vehicles and/or roadside stations.

The vehicle 100 may include a power supply 110 for powering the components. In some embodiments, the power source 110 may include a rechargeable lithium ion or lead acid battery. For example, the power source 110 may include one or more batteries configured to provide power. Other types of power sources may also be used with the vehicle 100. In an example embodiment, the power source 110 and the energy source 119 may be integrated into a single energy source.

The vehicle 100 may also include a computer system 112 to perform operations such as those described herein. As such, the computer system 112 may include at least one processor 113 (which may include at least one microprocessor), the processor 113 being operable to execute instructions 115 stored in a non-transitory computer-readable medium, such as the data storage device 114. In some embodiments, the computer system 112 may represent multiple computing devices that may be used to control various components or subsystems of the vehicle 100 in a distributed manner.

In some embodiments, the data storage device 114 may contain instructions 115 (e.g., program logic) that are executable by the processor 113 to perform various functions of the vehicle 100, including those described above in connection with fig. 1. The data storage 114 may also contain additional instructions, including instructions to transmit data to, receive data from, interact with, and/or control one or more of the propulsion system 102, the sensor system 104, the control system 106, and the peripheral devices 108.

In addition to instructions 115, data storage 114 may also store data such as road maps, route information, and other information. Such information may be used by the vehicle 100 and the computer system 112 during operation of the vehicle 100 in autonomous, semi-autonomous, and/or manual modes.

The vehicle 100 may include a user interface 116 for providing information to a user of the vehicle 100 or receiving input from a user of the vehicle 100. The user interface 116 may control or enable control of the content and/or layout of interactive images that may be displayed on the touch screen 148. Additionally, the user interface 116 may include one or more input/output devices within the set of peripherals 108, such as a wireless communication system 146, a touch screen 148, a microphone 150, and a speaker 152.

The computer system 112 may control the functions of the vehicle 100 based on inputs received from various subsystems (e.g., the propulsion system 102, the sensor system 104, and the control system 106) and from the user interface 116. For example, the computer system 112 may utilize inputs from the sensor system 104 in order to estimate outputs generated by the propulsion system 102 and the control system 106. Depending on the embodiment, the computer system 112 may be operable to monitor many aspects of the vehicle 100 and its subsystems. In some embodiments, the computer system 112 may disable some or all of the functionality of the vehicle 100 based on signals received from the sensor system 104.

The components of the vehicle 100 may be configured to work in an interconnected fashion with other components within or outside of their respective systems. For example, in an example embodiment, the camera 130 may capture a plurality of images that may represent information about the state of the environment of the vehicle 100 operating in the autonomous mode. The state of the environment may include parameters of a road on which the vehicle is operating. For example, the computer vision system 140 may be capable of identifying a grade (gradient) or other feature based on multiple images of the road. Additionally, a combination of GPS 122 and features identified by computer vision system 140 may be used with map data stored in data storage device 114 to determine specific road parameters. In addition, radar unit 126 may also provide information about the surroundings of the vehicle.

In other words, a combination of various sensors (which may be referred to as input indicating sensors and output indicating sensors) and the computer system 112 may interact to provide an indication of the inputs provided to control the vehicle or an indication of the surroundings of the vehicle.

In some embodiments, the computer system 112 may make determinations about various objects based on data provided by systems other than a radio system. For example, the vehicle 100 may have a laser or other optical sensor configured to sense objects in the field of view of the vehicle. The computer system 112 may use the outputs from the various sensors to determine information about objects in the field of view of the vehicle, and may determine distance and direction information to the various objects. The computer system 112 may also determine whether the object is desired or undesired based on the output from the various sensors.

Although fig. 1 illustrates various components of the vehicle 100, i.e., the wireless communication system 146, the computer system 112, the data storage device 114, and the user interface 116, as being integrated into the vehicle 100, one or more of the components may be mounted or associated separately from the vehicle 100. For example, the data storage device 114 may exist partially or completely separate from the vehicle 100. Thus, the vehicle 100 may be provided in the form of apparatus elements that may be placed separately or together. The device elements making up the vehicle 100 may be communicatively coupled together in a wired and/or wireless manner.

According to example embodiments, fig. 2A illustrates a front view of the vehicle 200, fig. 2B illustrates a side view of the vehicle 200, fig. 2C illustrates a perspective view of the vehicle 200, and fig. 2D illustrates a top view of the physical configuration of the vehicle. As such, fig. 2A-2D together illustrate an example physical configuration of a vehicle 200, which may represent one possible physical configuration of the vehicle 100 described with reference to fig. 1. Depending on the embodiment, the vehicle 200 may include a sensor unit 202, a wireless communication system 204, a radar unit 206, a LIDAR unit 208, and a camera 210, among other possible components. For example, the vehicle 200 may include some or all of the elements of the components described in fig. 1. Although the vehicle 200 is depicted in fig. 2 as a semi-truck, the vehicle 200 may have other configurations in examples, such as an automobile, a van, a motorcycle, a bus, a shuttle, a golf cart, an off-road vehicle, a robotic device, an agricultural vehicle, or other trailer-towing vehicle, among other possible examples.

The sensor unit 202 may include one or more sensors configured to capture information of the surroundings of the vehicle 200. For example, sensor unit 202 may include any combination of cameras, radars, LIDAR, range finders, radio (e.g., bluetooth and/or 802.11) and acoustic sensors, among other possible types of sensors. In some embodiments, sensor unit 202 may include one or more movable mounts operable to adjust the orientation of the sensors in sensor unit 202. For example, the moveable mount may include a rotating platform that can scan sensors to obtain information from each direction around the vehicle 200. The movable mount of the sensor unit 202 may also be movable in a scanning manner within a particular angular and/or azimuthal range.

In some embodiments, the sensor unit 202 may include mechanical structures that enable the sensor unit 202 to be mounted on the roof of a truck. Further, in examples, other mounting locations are possible.

The wireless communication system 204 may have a location relative to the vehicle 200 as depicted in fig. 2D, but may also have a different location. The wireless communication system 204 may include one or more wireless transmitters and one or more receivers that may communicate with other external or internal devices. For example, the wireless communication system 204 may include one or more transceivers for communicating with the user's equipment, other vehicles and road elements (e.g., signs, traffic lights), and possibly other entities. As such, the vehicle 200 may include one or more vehicle communication systems for facilitating communications, such as Dedicated Short Range Communications (DSRC), Radio Frequency Identification (RFID), and other proposed communication standards for intelligent transportation systems. The communication system 204 may include a cellular or wireless data connection. The communication system 204 may be configured to communicate with remote computing systems. The remote computing system may be configured to provide instructions and/or data to the vehicle 200 to assist its autonomous operation.

Vehicle 200 may include several radar units 206 at various locations. In one example, vehicle 200 may include a radar unit located on each of the front and rear bumpers of the cab portion. Further, the vehicle 200 may include two radar units located on each side of the vehicle 200, near the side view mirrors. Two radar units on the sides of the vehicle may be positioned so that one images the front right, one images the front left, one images the rear right, and one images the rear left. Each radar unit may be configured to transmit and receive radar signals over an angular region defined by a beamwidth of the radar unit. In some examples, each radar unit may be capable of performing beam steering on either transmit or receive beams. By using beam steering, the radar unit may be able to interrogate predefined angular directions.

The vehicle 200 may also include LIDAR units 208 mounted at various locations. For example, the LIDAR unit 208 may also be mounted on the side of the vehicle 200 near the rear view mirror. The LIDAR unit 208 may be configured to transmit the incoming and received light signals from an area surrounding the vehicle. The LIDAR unit 208 may be capable of imaging an area around the vehicle 200 from which light reflections are received.

The camera 210 may have various positions relative to the vehicle 200, such as a position above a front windshield of the vehicle 200. As such, the camera 210 may capture an image of the environment. For example, the camera 210 may capture images from a forward looking view relative to the vehicle 200, although other mounting locations (including movable mounts) and perspectives of the camera 210 are possible in embodiments. In some examples, the camera 210 may correspond to one or more visible light cameras, but may also be other types of cameras (e.g., infrared sensors). The camera 210 may also include optics that may provide an adjustable field of view.

FIG. 3 illustrates an example autonomous vehicle 300 with various sensor fields of view. As previously discussed with respect to fig. 2A-2D, the vehicle 300 may include a plurality of sensors. The positions of the various sensors may correspond to the positions of the sensors disclosed in fig. 2A-2D. However, in some cases, the sensor may have other locations. To simplify the drawing, the sensor positions are omitted from fig. 3. Fig. 3 shows a representative field of view for each sensor unit of the vehicle 300. The field of view of the sensor may include an angular region over which the sensor may detect an object.

In some embodiments, vehicle 300 may include five radar units. The first radar unit may be positioned to have a field of view to the left front of the vehicle and have an angular field of view corresponding to an angular portion of field of view 352A. The second radar unit may be positioned to have a field of view at the front right of the vehicle and have an angular field of view corresponding to an angular portion of field of view 352B. The third radar unit may be positioned to have a field of view to the left rear of the vehicle and have an angular field of view corresponding to an angular portion of field of view 352C. The fourth radar unit may be positioned to have a field of view at the right rear of the vehicle and have an angular field of view corresponding to an angular portion of field of view 352D. The fifth radar unit may be positioned at the front of the vehicle and have an angular field of view corresponding to an angular portion of the field of view 352E. Each of the five radar units may be configured with a scannable beamwidth of 90 degrees. The radar beam width may be less than 90 degrees, but each radar unit may be capable of steering a radar beam across a 90 degree field of view.

The first LIDAR unit of the vehicle 300 may be configured to scan the entire 360 degree area around the vehicle, as shown by the angular field of view corresponding to the angular portion of the field of view 356. The second LIDAR unit of the vehicle 300 may be configured to scan an area that is less than a 360 degree area around the vehicle. In one example, the second LIDAR unit may have a field of view in the horizontal plane of less than 10 degrees, as shown by the angular field of view corresponding to the angular portion of the field of view 354. The vehicle 300 may also include two side view LIDAR's with respective fields of

view

358A and 358B. Although side view LIDAR is shown with a 90 degree field of view, in some examples, each side view LIDAR may have a 180 degree field of view.

Further, the vehicle may also include at least one camera. The camera may be an optical camera and/or an infrared camera. The field of view of the camera is omitted from fig. 3.

FIG. 4 illustrates beam steering of a sensor for a vehicle 402 according to an example embodiment. In some examples, the sensor of the vehicle 402 may be a radar sensor. In some other examples, the sensor may be a LIDAR sensor. In some examples, during operation of the sensor, the sensor may be scanned within a field of view of the sensor. The various scan angles for the example sensor are shown as regions 404, each of which indicates an angular region over which the sensor operates. The sensor may periodically or iteratively change the region in which it is operating. In some embodiments, the vehicle 402 may use multiple sensors to measure the area 404. Further, other regions may be included in other examples. For example, one or more sensors may measure aspects of the trailer of the vehicle 402 and/or the area directly in front of the vehicle 402.

At some angles, the operational area 405 of the sensor may include the

rear wheels

406A, 406B of the trailer 403. Thus, the sensors may measure the rear wheels 406A and/or 406B during operation. For example, the

rear wheels

406A, 406B may reflect LIDAR or radar signals transmitted by the sensors. The sensors may receive reflected signals from the

rear wheels

406A, 406B. Thus, the data collected by the sensor may include data from reflections off the wheel.

In some cases, such as when the sensor is a radar sensor, reflections from the

rear wheels

406A, 406B may appear as noise in the received radar signal. Thus, in the event that the rear wheels 406 reflect radar signals back to the sensor, the radar system may operate with a reduced signal-to-noise ratio.

Fig. 5 illustrates sensors measuring wheel speed. In the exemplary embodiment, system 500 shows sensor 502 capturing measurements of a wheel 504 traveling on a road 506. This embodiment is included for illustrative purposes and does not show other potential elements of the system 500 (such as other portions of the vehicle pulling the trailer or portions of the trailer other than the wheels 504). As such, in other embodiments, system 500 may include more or fewer components.

Sensor 502 represents any type of sensor that may be positioned on a vehicle and have a field of view that includes a wheel 504. For example, the sensor 502 may be a camera, radar unit, LIDAR, or other type of sensor. For purposes of illustration, in the embodiment shown in fig. 5, sensor 502 is depicted as a radar unit that can transmit a signal 516 that bounces off wheel 504 and reflects toward and is received by sensor 502.

The wheels 504 may represent trailer wheels located on a front or rear axle of a trailer coupled to the vehicle including the sensor 502. For example, the wheels 504 may be the rear wheels of a trailer pulled by a semi-truck, similar to the example embodiment shown in fig. 4. As such, the sensor 502 may capture a measurement using the radar signal reflected from the wheel 504 and use the measurement to estimate the current rotational speed of the wheel 504. The diameter 520 of the wheel 504 may be provided to the processing unit for use in estimating the wheel speed. For example, the diameter 520 of the wheel 504 may be obtained from user input or via communication with a database indicating wheel diameters for various types of wheels. In some embodiments, the sensor 502 or another vehicle sensor may be used to estimate the diameter 520 of the wheel 504.

As wheel 504 rotates toward sensor 502, sensor 502 may transmit signal 516 toward a different portion of wheel 504. The signal 516 may bounce off different portions of the wheel 504 rotating at different speeds. In particular, some signals may reflect from an outer portion 508 of the wheel 504, while other signals may reflect from an inner portion 510 of the wheel 504. As the measurement point extends away from the center of the wheel 504, the rotational speed of the wheel 504 increases. At the center, the rotation is close to zero, and the rotation gradually increases as one moves away from the center to capture measurements. The increased size of the arrows within the

speed measurements

512, 514 are used to represent the increased wheel speed detected by the sensor 502.

As further shown in fig. 5, the sensor 502 may capture a speed measurement 512 of an upper region of the wheel 504, the speed measurement 512 being directed toward the sensor 502 as the wheel 504 rotates in that direction during forward travel of the vehicle. As such, the speed measurement 512 shows that a greater speed is measured from the outer portion 508 of the wheel 504 relative to the speed captured from the inner portion 510 of the wheel 504. Speed measurement 514 is similarly captured by sensor 502 measuring the lower region of wheel 504. A speed measurement 514 is shown extending away from the sensor 502 due to forward rotation of the wheel 504 caused by forward travel of the vehicle. The system 500 may perform similar techniques when the vehicle is in reverse. In such an example, the

speed measurements

512, 514 would have a direction opposite to that shown in FIG. 5.

The system 500 may use the

speed measurements

512, 514 to determine the rotational speed of the wheels 504. In particular, using the different returns measured from the wheel 504, the computing device may determine the rotational speed of the wheel 504 based on the diameter 520 of the wheel 504 using the following equation:

in particular, the system 500 may use the maximum observed speeds (positive or negative) from the

speed measurements

512, 514. In some cases, the maximum observed speed corresponds to a measurement captured from the exterior 508, which may be used to estimate the current rotational speed ω of the wheels 504.

In some embodiments, the system 500 may measure the rotational speed ω of the wheel 504 using one or more sensors by comparing the frequency spectra returned in the

speed measurements

512, 514. For example, a short radar pulse (e.g., 500MHz) may be reflected and slightly distorted by the wheel 504. The portion of the wheel 504 that rotates toward the sensor 502 may cause a doppler shift to a higher frequency and the backward portion may cause a corresponding doppler shift to a lower frequency. The result of these doppler shifts may produce a spectral response of the radar pulses transmitted and received by sensor 502. As such, the system 500 may use the highest or lowest frequency to determine the rotational speed ω of the wheels 504.

The system 500 may also involve using the rotational speed ω of the wheels 504 to perform various inspections of the trailer. For example, the system 500 may monitor the rotational speed ω of the wheels 504 during navigation (e.g., during a turn), compare the rotational speed ω of the wheels 504 to the rotational speeds of other wheels on the trailer, to monitor the health of the wheels 504 and corresponding components (e.g., axles), and/or to perform other operations.

Fig. 6 is a flow diagram of an example method 600, which may include one or more operations, functions, or actions, as depicted by one or more of

blocks

602, 604, 606, 608, and 610, each of which may be performed by any of the systems shown in the other figures, as well as possibly other systems.

Those skilled in the art will appreciate that the flow charts described herein illustrate the function and operation of certain embodiments of the present disclosure. In this regard, each block of the flowchart illustrations may represent a module, segment, or portion of program code, which comprises one or more instructions executable by one or more processors for implementing the specified logical function or step in the process. The program code may be stored on any type of computer readable medium, such as a storage device including a disk or hard drive, for example.

Further, each block may represent circuitry that is wired to perform a particular logical function in the process. As one of ordinary skill in the art will appreciate, alternative implementations are included within the scope of the example implementations of the present application, in which functions may be performed out of the order shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved. Further, in some examples, one or more blocks may be performed multiple times simultaneously. For example, block 602 may be performed multiple times simultaneously for each radar unit (or subset thereof) on the vehicle. In an example, the computing system may cause the vehicle and the radar system to perform one or more blocks of the method 600.

Additionally, method 600 is described with respect to a vehicle radar system. However, in other examples, different types of sensors may be used. For example, method 600 may be performed using a camera, a wheel speed sensor, and/or a LIDAR.

Block 602 relates to receiving radar reflections at the radar unit. In particular, the radar unit may be coupled to a vehicle (e.g. a tractor unit of a semi-truck) such that the radar unit has a field of view comprising at least one wheel coupled to a trailer of the vehicle. The vehicle may include a plurality of radar units coupled in a similar manner to measure operation of a plurality of wheels of the vehicle. In some arrangements, multiple sensors may obtain measurements from the same trailer wheel. The multiple sensors may include the same type of sensor (e.g., one or more radar units) or different types of sensors (e.g., a camera and a radar unit). In some examples, multiple radar units may simultaneously obtain and provide radar reflections corresponding to one or more wheels.

The radar unit may be configured to transmit radar into the surroundings of the vehicle. For example, the radar unit may be used to obtain measurements of one or more wheels of the trailer and measurements of the nearby environment. In some cases, the received radar signal may have a doppler shift based on the rotational speed of the wheel.

Block 604 relates to processing the received radar reflection signal by the radar processing system to determine a speed of at least one wheel of a trailer coupled to the vehicle. The radar processing system may be capable of using range and doppler information in the received radar reflections to determine which measurements correspond to the wheels of the trailer. Additionally or alternatively, the radar system may also use the angle information to determine which reflections are caused by the wheels of the trailer. In some cases, radar reflections caused by trailer wheels may appear as noise within the received radar signal before the processing system associates the radar measurements with the wheels.

In some examples, the radar processing system may receive radar reflections from the radar unit and remove noise within the radar reflections prior to determining the speed of one or more wheels of the trailer. As such, the radar processing system may then determine a speed of at least one wheel of the trailer in response to removing noise within the radar reflection.

Block 606 relates to receiving the expected wheel speed. The expected wheel speed measurement may be received by a control system of the vehicle or another computing system. Further, the expected wheel speed may be based on a wheel speed of a wheel of a cab portion of the vehicle.

In some examples, receiving the expected wheel speed measurement includes receiving actual wheel speeds of wheels of a cab portion of the vehicle and determining an expected wheel speed of wheels of a trailer portion of the vehicle. In some examples, the expected wheel speed of the wheels of the trailer portion may be equal to the wheel speed of the cab portion. In some examples, the expected wheel speed of the wheels of the trailer portion may be different from the wheel speed of the cab portion, such as when the vehicle is turning. As such, the computing system may train the neural network to learn the difference in expected wheel speeds based on various parameters of the vehicle (such as the weight of the trailer, the grade of travel, and/or the speed and heading of the vehicle, etc.).

In an embodiment, the vehicle may include one or more wheel speed sensors. For example, the wheel speed sensor may be connected to a cab of the vehicle. As such, the wheel speed sensor may be designed to obtain wheel speed data from one or more wheels of the vehicle. As such, the computing system may use the wheel speed data to determine an expected speed of the trailer.

In some examples, wheel speed measurements may be received from sensors (such as sensors configured to measure the speed of one or more wheels of a vehicle). The sensor may be configured to measure a rotational speed of the wheel (or axle) and determine a speed of the vehicle (e.g., a wheel speed) based on the rotational speed. In other examples, the wheel speed measurement may be calculated based on a known speed of the cab portion (such as by GPS) and determining the wheel speed based on the known speed.

Block 608 relates to determining, by the processor, a difference between the determined speed for the at least one wheel of the trailer and the expected wheel speed. The difference may be determined based on subtracting the tire speed from the expected wheel speed or subtracting the expected wheel speed from the tire speed. Thus, the processor may determine the difference between the measured tire speed and the expected value of the tire speed. In some examples, the difference may be compared to one or more tolerances (e.g., thresholds) during the comparison.

Block 610 relates to causing the vehicle to perform a corrective action in response to the difference exceeding the threshold. Causing the vehicle to perform the corrective action may involve causing the vehicle to perform an emergency braking action or procedure. For example, an emergency braking procedure includes safely navigating the vehicle to one side of the travel path and slowly decelerating the speed of the vehicle until safely stopped. In this manner, the vehicle may minimize potential problems, such as tire leakage or misalignment, that may occur when one or more trailer wheels are not operating in conjunction with the vehicle wheels due to various potential problems. The emergency braking procedure may involve using a set of brakes (e.g., cab brakes) of the vehicle with or without brakes associated with the trailer.

In other cases, the processor may cause the vehicle to perform a stability control action. The stability control action may involve slowing down and gradually straightening (straightening out) the path of the vehicle based on the detection of a difference exceeding a threshold. The stability control action may involve monitoring the road and surrounding environment using one or more sensors to ensure a safe and stable correction for the vehicle.

In some examples, the threshold may be a static threshold. The static threshold may be a single value (such as 5 miles per hour), or a percentage (such as 97% similarity). Thus, if the difference sum exceeds a single value, corrective action may be taken. Similarly, if the difference, expressed as a percentage of the speed, is below that percentage, the threshold may be exceeded. In other examples, the threshold may be changed dynamically. For example, the threshold may be dynamically changed based on movement of the vehicle (such as turning, etc.). In another example, the threshold may be changed based on the speed of the vehicle. In yet another example, the threshold may vary based on a security criteria. Safety standards may be based on operating conditions (such as traffic or weather), the payload of the truck (what the truck carries in a trailer), road dynamics (such as highway driving or construction), or other criteria.

In another embodiment, the processor may determine that the vehicle is performing a turning movement and adjust the threshold based on the degree of turning movement (i.e., the degree of turning). In particular, the wheel speeds of the trailer and vehicle may vary during the execution of a turn, relative to differences during straight-ahead navigation.

Exceeding the threshold may indicate some type of error in the system(s) of the vehicle. For example, if the vehicle is traveling in a straight line, the speed of the wheels of the cab portion and the trailer portion should be equal. If not, the system may determine that an error exists. The error may be determined as a measurement error of the speed of the cab wheels or a rotation error of the wheels of the trailer, such as a stuck axle or a flat tire. In response to determining the error, the vehicle may perform a corrective action. Corrective action may include ignoring incorrect speed measurements of the cab wheels, determining that trailer operation is unsafe and stopping driving, or other possible actions.

In another example, the system may be capable of monitoring wheel speeds during vehicle movement such as turning or braking. The system may be able to determine whether the brake is functioning properly, e.g., the brake is locked or not engaged properly. If the brakes do not function properly, the control system may be able to modulate the application of the brakes to prevent deadlock. In other examples, the vehicle may activate a backup braking system or method if the brakes are not properly engaged.

In yet another example, the system may be capable of monitoring a controlled reduction of the trailer, such as slip, based on the measured wheel speeds. The control system may be capable of adjusting a control scheme or maneuver of the vehicle in response to a loss of control.

Additionally, the radar system may be capable of determining radar reflections associated with the tire(s) of the trailer. The radar system may use range, angle, and doppler measurements to determine which radar reflections are from the tire(s). The radar system may then be able to filter tire reflections from the radar reflection signal to reduce noise in the received radar signal.

In some examples, method 600 may also involve determining a wheel speed of a wheel coupled to the vehicle using a sensor coupled to the vehicle. As such, the processor may then determine an expected wheel speed of the wheel coupled to the trailer based on the wheel speed of the wheel coupled to the vehicle.

In an additional example, method 600 may involve receiving a second radar reflection at a second radar unit. In particular, the second radar unit may be coupled to the vehicle such that the second radar unit has a field of view that includes a second wheel coupled to a trailer of the vehicle. The second wheel of the trailer may be different from the at least one wheel of the trailer measured by the further radar unit. Thus, the vehicle may have a rig with redundant radar units coupled to measure a plurality of wheels of the trailer. As such, method 600 may also involve processing, by the radar processing system, the second radar reflection to determine a speed of the second wheel of the trailer, and performing a comparison between the speed determined for the at least one wheel of the trailer and the speed determined for the second wheel of the trailer. Based on the comparison, the processor may control the vehicle.

In another embodiment, the method 600 may involve determining that a difference between the speed determined for at least one wheel of the trailer and the speed determined for a second wheel of the trailer exceeds a threshold difference. Based on the determination, the processor may cause the vehicle to execute an emergency braking procedure. As indicated above, the emergency braking procedure may involve safely navigating the vehicle to one side of the travel path and slowly decelerating the speed of the vehicle. In some cases, the processor may also provide an external signal that communicates the execution of the emergency braking procedure to an external source (e.g., another vehicle or a central computing network that monitors multiple vehicles). The process may also determine that a difference between the speed determined for at least one wheel of the trailer and the speed determined for a second wheel of the trailer is below a threshold difference. In such a determination, the processor may control the vehicle according to the current navigation strategy.

In some examples, the computing system may determine a system of an anti-lock braking system. In response, the computing system may perform a corrective braking action.

FIG. 7 is a method for determining the rotational speed of the trailer wheels. The method 700 may include one or more operations, functions, or actions, as depicted by one or more of the

blocks

702, 704, and 706, each of which may be performed by any of the systems shown in the other figures, as well as possibly other systems.

At block 702, the method 700 involves transmitting, by a computing device coupled to a vehicle, a radar signal by a radar unit toward wheels of a trailer. The trailer is coupled to the vehicle and the radar unit has a field of view that includes wheels.

In some examples, the vehicle is a semi-truck pulling a trailer. As such, the semi-truck may include one or more radar units positioned such that the radar units may transmit signals in the direction of one or more trailer wheels. The computing device may cause the radar unit to transmit the radar signal as a pulse toward the vehicle.

At block 704, the method 700 involves receiving radar reflections corresponding to radar signals reflected from the wheel. The computing device may receive radar reflections corresponding to pulses reflected from the wheel and determine a frequency spectrum based on the radar reflections. The computing device may identify particular frequencies based on the frequency spectrum. For example, the computing device may use the frequency spectrum to identify the highest frequencies or the lowest frequencies.

In block 706, method 700 involves determining a rotational speed of the wheel based on the radar reflection. In some examples, the computing device may determine the rotational speed of the wheel based on a particular frequency (e.g., the highest or lowest frequency) and the radius of the wheel.

In some examples, method 700 may involve determining an observed maximum frequency based on radar reflections and determining a rotational speed of the wheel based on the observed maximum frequency and a radius of the wheel.

Method 700 may also involve controlling the vehicle based on the rotational speed of the wheels. For example, the computing device may determine that the rotational speed indicates that the trailer may require maintenance (e.g., tire deflation).

In some examples, the computing device may direct the radar unit or a second radar unit toward a second wheel of the trailer. For example, the computing device may cause a pair of radar units to transmit radar signals toward different trailer wheels simultaneously. The computing device may receive radar reflections bouncing off the second trailer wheel and use the radar reflections to determine a rotational speed of the second wheel. The computing device may compare the rotational speeds of the different tires and perform an operation based on the comparison. For example, the computing device may use the comparison to identify when the trailer wheels are not operating properly. The computing device may control the vehicle based on the comparison. In some cases, the computing device may provide instructions to the control system based on the comparison.

In some cases, the computing device may determine that a difference between the rotational speed of the wheel and the rotational speed of the second wheel exceeds a threshold (e.g., a threshold rotational speed difference). The computing device may provide instructions to a control system of the vehicle to gradually slow down and stop the vehicle. The speed at which the gradual deceleration process occurs (pace) may depend on the current speed and heading of the vehicle, among other factors. For example, when the vehicle is navigating at a high speed (e.g., on a highway), the duration of deceleration may be longer, while when the vehicle is traveling at a lower speed (e.g., not on a highway), the duration of deceleration may be shorter.

Fig. 8 is a schematic diagram illustrating a conceptual partial view of an example computer program product including a computer program for executing a computer process on a computing device, arranged in accordance with at least some embodiments presented herein. In some embodiments, the disclosed methods may be implemented as computer program instructions encoded in a machine-readable format on a non-transitory computer-readable storage medium or on other non-transitory media or articles of manufacture.

The example computer program product 800 may be provided using a signal bearing medium 802 and may include one or more programming instructions 804, which when executed by one or more processors may provide the functions or portions of the functions described above with respect to fig. 1-7. In some examples, the signal bearing medium 802 may encompass a non-transitory computer readable medium 806, such as, but not limited to, a hard disk drive, a Compact Disc (CD), a Digital Video Disc (DVD), a digital tape, a memory, and the like. In some implementations, the signal bearing medium 802 may encompass a computer recordable medium 808 such as, but not limited to, a memory, a read/write (R/W) CD, a R/W DVD, and the like. In some implementations, the signal bearing medium 802 may encompass a communication medium 810 such as, but not limited to, a digital and/or analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link, etc.). Thus, for example, the signal bearing medium 802 may be communicated over a wireless form of the communication medium 810.

The one or more programming instructions 804 may be, for example, computer-executable and/or logic-implemented instructions. In some examples, a computing device, such as computer system 112 of fig. 1, may be configured to provide various operations, functions, or actions in response to programming instructions 804 conveyed to computer system 112 by one or more of computer-readable media 806, computer-recordable media 808, and/or communication media 810.

The non-transitory computer readable medium may also be distributed among multiple data storage elements, which may be remotely located from each other. The computing device executing some or all of the stored instructions may be a vehicle, such as vehicle 200 shown in fig. 2A-2D, among other possibilities. Alternatively, the computing device executing some or all of the stored instructions may be another computing device, such as a server.

The above detailed description describes various features and functions of the disclosed systems, devices, and methods with reference to the accompanying drawings. While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope being indicated by the following claims.

It should be understood that the arrangements described herein are for example purposes only. As such, those skilled in the art will recognize that other arrangements and other elements (e.g., machines, devices, interfaces, functions, orders, groupings of functions, etc.) may be used instead, and some elements may be omitted altogether, depending upon the desired results. In addition, many of the elements described are functional entities that may be implemented as discrete or distributed components or in conjunction with other components, in any suitable combination and location.

Claims

1. A system, comprising:

a radar unit coupled to the vehicle, wherein the vehicle is towing a trailer, and wherein the radar unit has a field of view that includes wheels of the trailer; and

a computing device configured to:

causing a radar unit to transmit a radar signal towards the wheel;

receiving radar reflections corresponding to radar signals reflected from the wheel; and is

Determining a rotational speed of the wheel based on the radar reflection.

2. The system of claim 1, wherein the computing device is further configured to:

causing a radar unit to transmit a radar signal as a pulse towards the wheel;

identifying a particular frequency from a spectrum corresponding to the radar reflection; and is

Determining a rotational speed of the wheel based on the particular frequency and the radius of the wheel.

3. The system of claim 2, wherein the particular frequency corresponds to a highest frequency in a frequency spectrum.

4. The system of claim 2, wherein the particular frequency corresponds to a lowest frequency in a frequency spectrum.

5. The system of claim 1, wherein the computing device is further configured to:

identifying an observed maximum frequency in the radar reflection; and is

Determining a rotational speed of the wheel based on the observed maximum frequency and the radius of the wheel.

6. The system of claim 1, wherein the computing device is further configured to:

the vehicle is brought to a gradual stop based on the rotational speed of the wheels of the trailer.

7. The system of claim 1, wherein the computing device is further configured to:

causing a second radar unit to transmit a radar signal toward a second wheel of the trailer;

receiving a radar reflection corresponding to a radar signal reflected from the second wheel; and is

Determining a rotational speed of the second wheel based on a radar reflection corresponding to a radar signal reflected from the second wheel.

8. The system of claim 7, wherein the computing device is further configured to:

performing a comparison between the rotational speed of the wheel and the rotational speed of the second wheel; and is

Based on the comparison, an instruction is provided to a control system of the vehicle.

9. The system of claim 8, wherein the computing device is further configured to:

determining that a difference between the rotational speed of the wheel and the rotational speed of the second wheel exceeds a threshold; and is

Instructions are provided to a control system of the vehicle to gradually decelerate and stop the vehicle.

10. The system of claim 9, wherein the threshold value is dependent on a steering angle and a speed of the vehicle.

11. The system of claim 1, wherein the computing device is further configured to:

the vehicle is controlled based on the rotational speed of the wheels.

12. A method, comprising:

causing, by a computing device coupled to a vehicle, a radar unit to transmit a radar signal toward a wheel of a trailer, wherein the trailer is coupled to the vehicle, and wherein the radar unit has a field of view that includes the wheel;

Determining a rotational speed of the wheel based on the radar reflection.

13. The method of claim 12, wherein causing a radar unit to transmit a radar signal toward the wheels of a trailer comprises:

causing the radar unit to transmit a pulse towards the wheel.

14. The method of claim 13, further comprising:

receiving radar reflections corresponding to pulses reflected from the wheel;

determining a frequency spectrum based on the radar reflection;

identifying a particular frequency based on the frequency spectrum; and is

Wherein determining the rotational speed of the wheel comprises:

determining a rotational speed of the wheel based on the specific frequency and the radius of the wheel.

15. The method of claim 14, wherein identifying particular frequencies based on a frequency spectrum comprises:

the highest frequency in the spectrum is identified.

16. The method of claim 14, wherein identifying particular frequencies based on a frequency spectrum comprises:

the lowest frequency in the spectrum is identified.

17. The method of claim 12, further comprising:

determining an observed maximum frequency based on the radar reflection; and is

Wherein determining the rotational speed of the wheel comprises:

18. The method of claim 12, further comprising:

controlling the vehicle based on the rotational speed of the wheel.

19. A non-transitory computer-readable medium configured to store instructions that, when executed by a computing system, cause the computing system to perform operations comprising:

causing a radar unit to transmit radar signals towards wheels of a trailer, wherein the trailer is coupled to a vehicle, and wherein the radar unit has a field of view that includes the wheels;

Determining a rotational speed of the wheel based on the radar reflection.

20. The non-transitory computer readable medium of claim 19, further comprising:

determining an observed maximum frequency based on the radar reflection; and is

Wherein determining the rotational speed of the wheel comprises: