BACKGROUND

Driving on worn, low-tread, and low-pressure tires can create a safety hazard for the driver and passengers of a vehicle, as well as others who may encounter a vehicle traveling on worn, low-tread tires. For example, a vehicle traveling on worn, low-tread, and/or low-pressure tires may be unable to stop suddenly and efficiently while traveling on roads during inclement weather, such as rain, snow, ice, or mud. This can result in a collision involving the vehicle that could have been otherwise avoided, and such collisions can cause property damage and/or personal injury.

Tire treads are designed to maintain solid contact and grip on the road even during inclement weather. Driving on tires with insufficient treads (i.e., balding or low-tread tires) can provide an increased risk of hydroplaning and/or can result in decreased handling of the vehicle. Moreover, driving can create friction between tires and the road, and tire treads can function to help cool the tires, reducing the effects of the heat caused by driving. Low-tread tires can reduce the ability of the tire to cool, resulting in the heat experienced by the tires to reach unsafe levels. This can ultimately result in a blowout, which could cause a driver to lose control of a vehicle, especially while traveling at high speeds.

In addition, low-tread tires generally retain air less efficiently than tires with sufficient tread depth. Thus, low-tread tires can be more susceptible to becoming low-pressure tires. Improperly inflated tires are typically unable to properly grip the road, regardless of road conditions, making it more difficult for a driver to steer the vehicle. Improperly inflated tires can also cause a vehicle to skid during sudden stops, can reduce gas mileage of a vehicle, and/or can cause the tire tread to wear more quickly. As another example, low-tread tires can be more susceptible blowouts after suffering a puncture as the tire no longer have sufficient material to resist a blowout (e.g., resist shearing of the tire caused by the internal pressure of the tire) when the tire experiences a puncture.

Existing tires and related systems can include pressure sensors that can provide information regarding the pressure of the tire, but there is a need to track the tread depth of a tire, as well as other information that can be pertinent to the health of a tire.

SUMMARY

These and other problems can be addressed by the technology disclosed herein, which includes a system configured to monitor the health of a tire. The system can include an inertial measurement unit (IMU). The IMU can be adhered or attached within a tire and/or to a wheel (e.g., a hub) and can measure linear accelerations and angular velocities associated with the wheel. The system can analyze the data measured by the IMU to determine various measures of tire health. For example, the system can determine an estimated tread depth of the tire, as well as qualities associated with the contact patch, toe, and/or camber of the tire and/or corresponding wheel. The system can provide alerts to a computing device (e.g., a user's mobile device) indicating various qualities associated with the tire and/or vehicle, such as a measured use of the tire (e.g., service time, distance traveled), a determined health of the tire, and/or various measurements, metrics, or calculations associated with the tire.

The disclosed technology includes a tire monitoring system that can comprise a tire sensor mounted within a tire and a computing device in communication with the tire sensor. The computing device can be configured to receive kinematic sensor data from the tire sensor and determine a contact patch angle based at least in part on the kinematic sensor data. The kinematic sensor data can be indicative of motion of the tire, and the contact patch angle being an angle that represents a contact patch associated with the tire. The computing device can be configured to determine an estimated tread depth of the tire based at least in part on the contact patch angle and, responsive to determining that the estimated tread depth of the tire is a below a tread depth threshold, output instructions to a user device associated with the tire monitoring system. The instructions can instruct the user device to provide an indication for one or more suggested actions.

The tire sensor can be attached to an inner liner of the tire.

The tire sensor can be attached to a wheel hub associated with the tire.

The tire monitoring system can be configured such that determining the contact patch angle can include determining when the tire sensor enters the contact patch and when the tire sensor exits the contact patch.

The tire monitoring system can be configured such that (i) determining when the tire sensor enters the contact patch includes determining a first time or an entry angle associated with the tire sensor transitioning from an arc-like path to a cord-like path and (ii) determining when the tire sensor exits the contact patch comprises determining a second time or an exit angle associated with the tire sensor transitioning from the cord-like path to the arc-like path.

The tire monitoring system can be configured such that (i) determining when the tire sensor enters the contact patch comprises determining a first time or an entry angle associated with the kinematic sensor data passing a first kinematic data threshold and (ii) determining when the tire sensor exits the contact patch comprises determining a second time or an exit angle associated with the kinematic sensor data passing a second kinematic data threshold.

The computing device can be configured to receive tire data indicative of a model of the tire.

The one or more suggested actions can include instructions to rotate the tire with other tires of a vehicle associated with the tire, instructions to align the tire and the other tires, instructions to inflate the tire, and/or instructions to replace the tire.

The monitoring system of claim1, wherein the computing device is configured to determine the estimated tread depth only during periods in which the contact patch angle remains approximately constant during successive rotations of the tire.

The tire monitoring system can include a pressure sensor mounted inside the tire, and the pressure sensor can be configured to measure a pressure of the tire. The pressure sensor can be in communication with the computing device, and the computing device can be configured to receive, from the pressure sensor, pressure data that is indicative of the pressure of the tire and determine the estimated tread depth of the tire based at least in part on the contact patch angle and the pressure data.

The disclosed technology includes a method that can include receiving kinematic sensor data from a tire sensor, and the kinematic sensor data can be indicative of motion of a tire associated with the tire sensor. The method can include determining, based on the kinematic sensor data, a contact patch size associated with a contact patch of the tire and/or determining, based on the kinematic sensor data, a rotation rate of the tire. The method can include determining an estimated tread depth of the tire based at least in part on the contact patch size and/or the rotation rate and, responsive to determining that the estimated tread depth of the tire is a below a tread depth threshold, outputting instructions to a user device associated with the tire. The instructions can instruct the user device to provide an indication for one or more suggested actions.

Determining the contact patch size can include determining a contact patch angle that is indicative of an angular distance between entry of the tire sensor into the contact patch and exit of the tire sensor out of the contact patch. The angular distance can be calculated with respect to a center of the tire.

The method can include determining the estimated tread depth only during periods in which the contact patch angle remains approximately constant during successive rotations of the tire.

Determining the rotation rate of the tire can include calculating, based on the kinematic sensor data, a peak angular velocity and a mean angular velocity and calculating a peak tire rotation rate ratio by dividing the peak angular velocity by the mean angular velocity.

Calculating the peak angular velocity can include extracting a plurality of peak angular velocities for each of a plurality rotations of the tire and averaging the plurality of peak angular velocities, and calculating the mean angular velocity can include extracting a plurality of mean angular velocities for each of the plurality rotations of the tire and averaging the plurality of mean angular velocities.

The method can include receiving pressure data from pressure sensor and determining the estimated tread depth of the tire based at least in part on the contact patch size and the pressure data. The pressure data can be indicative of a pressure of the tire.

The disclosed technology includes a non-transitory, computer-readable medium storing instructions that, when executed by one or more processors, can cause a system to receive kinematic sensor data from a tire sensor. The kinematic sensor data can be indicative of motion of a tire associated with the tire sensor. The instructions, when executed by one or more processors, can cause the system to determine a rotation rate of the tire based on the kinematic sensor data, determine an estimated tread depth of the tire based at least in part on the rotation rate, and, responsive to determining that the estimated tread depth of the tire is a below a tread depth threshold, output instructions to a user device associated with the tire. The instructions can instruct the user device to provide an indication for one or more suggested actions.

Determining the rotation rate of the tire can include (i) calculating, based on the kinematic sensor data, a peak angular velocity and a mean angular velocity associated with the motion of the tire and (ii) calculate a peak tire rotation rate ratio by dividing the peak angular velocity by the mean angular velocity.

Calculating the peak angular velocity can include extracting a plurality of peak angular velocities for each of a plurality rotations of the tire and averaging the plurality of peak angular velocities, and calculating the mean angular velocity can include extracting a plurality of mean angular velocities for each of the plurality rotations of the tire and averaging the plurality of mean angular velocities.

Determining the contact patch size can include determining a contact patch angle based at least in part on when the tire sensor enters the contact patch and when the tire sensor exits the contact patch.

