Vehicle tow capacity estimator

Apparatus and methods are disclosed for a vehicle tow capacity estimator. An example disclosed vehicle includes memory and a processor. The example memory stores first and second acceleration profiles and a degradation factor table. The example processor, when a load is connected to the vehicle, determines a third acceleration profile and calculates a tow capacity ratio based on the first, second, and third acceleration profile, and a degradation factor. Additionally, the example processor, in response to the tow capacity ratio not satisfying a tow threshold, provides a warning.

TECHNICAL FIELD

The present disclosure generally relates to vehicle navigation and, more specifically, a vehicle tow capacity estimator.

BACKGROUND

Many vehicles have a hitch attached to the frame of the vehicle to allow customers to tow a range of loads, such as trailers, boats, and recreational vehicles, etc. Trucks often have hitches. Additionally, some cars and sports utility vehicles also have options for a towing package. The cars usually cannot tow as much as the trucks. Furthermore, the grade of the road may change over the route the car is towing the load. As a result, a customer may begin a trip by towing a load that is in excess of the vehicle's ability over the route on which the vehicle is traveling. This can result in undesirable scenarios such as overheating engine, transmission damage, interrupted vacation trip.

SUMMARY

Apparatus and methods are disclosed for a vehicle tow capacity estimator. An example disclosed vehicle includes memory and a processor. The example memory stores first and second acceleration profiles and a degradation factor table. The example processor, when a load is connected to the vehicle, determines a third acceleration profile and calculates a tow capacity ratio based on the first, second, and third acceleration profile, and a degradation factor. Additionally, the example processor, in response to the tow capacity ratio not satisfying a tow threshold, provides a warning.

An example method to protect a powertrain of a vehicle includes, when a load is connected to the vehicle, determining a first acceleration profile and calculating a tow capacity ratio based on the first acceleration profile, a second acceleration profile, a third acceleration profile, and a degradation factor. The second and third acceleration profiles are stored in memory. The example method also includes, in response to the tow capacity ratio not satisfying a tow threshold, providing a warning.

An example tangible computer readable medium comprising instructions that, when executed, cause a vehicle to, when a load is connected to the vehicle, determine a first acceleration profile and calculate a tow capacity ratio based on the first acceleration profile, a second acceleration profile, a third acceleration profile, and a degradation factor. The second and third acceleration profiles are stored in memory. Additionally, the instructions cause the vehicle to, in response to the tow capacity ratio not satisfying a tow threshold, provide a warning.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The tow capacity of a vehicle varies from powertrain to powertrain. Additionally, the tow capacity of the vehicle may change overtime. For example, a vehicle's towing capacity may degrade as various part of the vehicle age, such as the engine and/or the tires. As another example, some events, such as oil changes, engine tunings, installing new tires, etc., may improve the vehicle's towing capacity. Further, the vehicle's towing capacity changes based on a slope of the route on which the vehicle will be driven. As such, a driver can have problems determining the vehicle's tow capacity and estimate the weight of the load being towed.

As used herein, a slope of a road is measured in (a) an angle of inclination compared to the horizon or (b) a grade. The grade is a hundred times the tangent of the angle of inclination compared to the horizon. The slope may be upwards (the angle of inclination and the grade are positive), downwards (the angle of inclination and the grade are negative), or flat (e.g. the angle of inclination and the grade are zero). For example, the grade of Eisenhower Pass in Colorado, traveling west, is 6%. As the slope of a road increases, the tow capacity required to tow the load increases. Thus, a vehicle may be initially able to tow a load, but cannot once the slope of the road increases. As a result, the driver may begin to travel a route only to later discover that the degradation in the tow capacity over the route results in the vehicle not capable of towing the load in the middle of the route.

As disclosed below, a tow estimator estimates the two capacity of the vehicle over the route and provides a warning if the vehicle does not have enough tow capacity to complete the route. From time to time (e.g., after period of time, after a set number of miles, after a maintenance event, etc.), the tow estimator establishes a baseline tow capacity based on the average acceleration of the vehicle without the load while traversing a flat road. When the vehicle detects that the load is connected to the vehicle (e.g., via a hitch sensor, via a rear camera, etc.), the vehicle determines the weight of the load based on the average acceleration of the vehicle the load while traversing the flat road. The tow estimator analyzes road segments of a route to determine the maximum road grade on the route. As used herein, a road segment is a contiguous section of a road that has common characteristics (e.g., lane configurations, speed limit, elevation, slope, curvature, etc.). For example, a road segment may represent a portion of a highway with a substantially similar slope (e.g., ±0.5 percent grade, etc.). The tow estimator estimates the tow capacity of the vehicle with a degradation factor based on maximum road grade on the route. The degradation factor takes into account increased work to tow a load up roads with positive slopes. In some examples, a test vehicle may be driven on two inclines, such as one percent and six percent. The degradation factor is the difference in acceleration at the same throttle angle. In some such examples, a linear relationship is assumed to create a degradation factor table through interpolation.

To determine whether towing the load over the route is advisable, the tow estimator compares the degraded tow capacity to the estimated weight of the load. In some examples, the two estimator provides an alert if a ratio of the estimated weight of the load and the degraded tow capacity satisfies (e.g., is greater than or equal to) a towing threshold. In some such examples, the towing threshold is 80 percent. In some examples, the tow estimator determines whether another route to the destination exists on which the ratio of the estimated weight of the load and the degraded tow capacity satisfies the towing threshold. In such examples, the tow estimator recommends the alternate route. As a result, the tow estimator provides guidance of the actual tow capacity of the vehicle.

FIG. 1illustrated a vehicle100(e.g., a truck, a semi-trailer truck, a car, a van, a sport utility vehicle, etc.) towing a load102(e.g., a trailer, a board, a recreational vehicle, etc.) in accordance with the teachings of this disclosure. The vehicle100may be a standard gasoline powered vehicle, a hybrid vehicle, an electric vehicle, a fuel cell vehicle, and/or any other mobility implement type of vehicle. The vehicle100includes parts related to mobility, such as a powertrain with an engine, a transmission, a suspension, a driveshaft, and/or wheels, etc. The performance of the powertrain varies as parts of the powertrain wear over time, are replaced, and/or receive maintenance. The performance of the powertrain is a factor that determines a tow capacity of the vehicle100. The vehicle100may be non-autonomous, semi-autonomous (e.g., some routine motive functions controlled by the vehicle100), or autonomous (e.g., motive functions are controlled by the vehicle100without direct driver input). In the illustrated example the vehicle100includes an infotainment head unit104, sensors106and108, a hitch110, and a tow estimator112.

The infotainment head unit104provides an interface between the vehicle100and a user (e.g., the driver). The infotainment head unit104includes digital and/or analog interfaces (e.g., input devices and output devices) to receive input from the user(s) and display information. The input devices may include, for example, a control knob, an instrument panel, a digital camera for image capture and/or visual command recognition, a touch screen, an audio input device (e.g., cabin microphone), buttons, or a touchpad. The output devices may include instrument cluster outputs (e.g., dials, lighting devices), actuators, a heads-up display, a center console display (e.g., a liquid crystal display (“LCD”), an organic light emitting diode (“OLED”) display, a flat panel display, a solid state display, etc.), and/or speakers. The example infotainment head unit104includes hardware (e.g., a processor or controller, memory, storage, etc.) and software (e.g., an operating system, etc.) for an infotainment system (such as SYNC® and MyFord Touch® by Ford®, Entune® by Toyota®, IntelliLink® by GMC®, etc.). Additionally, the infotainment head unit104displays the infotainment system on, for example, the center console display. In some examples, the infotainment system includes a navigation application that provides road segment data (e.g., slopes of the road segments, curvature of the road, speed limits, etc.). Additionally or alternatively, the infotainment system may include an application that provides horizon data with topology information (such as, turn angles, road gradients, road features (e.g. tunnels, bridges, etc.), etc.), position information (e.g., coordinates from the GPS) and road information (such as speed limits, surface material, etc.) about the roads in the vicinity of the vehicle100.

The sensors106and108may be arranged in and around the vehicle100in any suitable fashion. In the illustrated example, the sensors include a yaw and pitch sensor106and a speed sensor108. The yaw and pitch sensor106measures the inclination of the vehicle100. For example, the tow estimator112, via the yaw and pitch sensor106determines when the vehicle100is on a flat road. The speed sensor108may be a wheel speed sensor or a driveshaft sensor. The speed sensor108provides the speed of the vehicle100.

The hitch110that allows the load102to be physically coupled to the vehicle100. The hitch110includes a hitch connector114that facilitates the detecting when the load102is physically coupled to the vehicle100. Additionally, in some examples, the hitch connector114facilitates the load102being communicatively coupled to a vehicle data bus (e.g., the vehicle data bus ofFIG. 3below) of the vehicle100. When the load102is connected to the vehicle data bus via the hitch connector114, the vehicle100can control the systems of the load102, such as lights, brakes, and stability control, etc. Alternatively or additionally, in some examples, the vehicle100includes a camera to detect the presence of the load102.

As disclosed in more detail inFIG. 2below, the tow estimator112determines whether the tow capacity of the vehicle100is sufficient to tow the load102via a particular route to a destination. To determine the sufficiency of the tow capacity, the tow estimator112determines a baseline acceleration profile (APBASE) of the vehicle100. The tow estimator112determines the baseline acceleration profile of the vehicle100from time-to-time. In some examples, the tow estimator112determines the baseline acceleration profile based on (i) mileage (e.g., every 10,000 miles, every 50,000 miles, etc.), (ii) timing (e.g., monthly, weekly, yearly. etc.), and/or (iii) in response to a maintenance event (e.g., an oil change, a engine tuning, a tire rotation, etc.) The baseline acceleration profile is based on the average acceleration of the vehicle100on a flat surface. In some examples, the tow estimator112determines the acceleration of the vehicle100, from a stop, over a period of time (e.g., a day, a week, etc.).

Additionally, the tow estimator112includes (a) an unloaded acceleration profile of the vehicle100when the vehicle100is manufactured (sometimes referred to herein as a “manufacture acceleration profile” (APMAN)) and (b) a manufacture maximum acceleration profile (APMMAX) of the vehicle100when the vehicle is manufactured. The manufacture maximum acceleration profile (APMMAX) measures the acceleration profile of the vehicle100when the vehicle is towing at its maximum tow capacity. In some examples, the manufacture acceleration profile (APMAN) and the manufacture maximum acceleration profile (APMMAX) are determined during a text process via, for example, a post-manufacture test on dynamometers. The tow estimator112detects when the load102is connected to the hitch110. When the load102is connected to the hitch110, the tow estimator112determines a loaded acceleration profile (APLOAD) for the vehicle100. In some examples, the tow estimator112determines the acceleration of the vehicle100, from a stop, when the load102is connected to the vehicle100. In some examples, the tow estimator112, via the infotainment head unit104, instructs the driver to accelerate from a stop on a flat surface with the load102connected.

When a destination is input into the navigation application (e.g., via the infotainment head unit104), the tow estimator112receives road segment information about the route selected by the navigation system. The tow estimator112determines the maximum grade of the road segments. The tow estimator112determines a degradation factor based on the maximum grade. Based on the manufacture acceleration profile (APMAN), the manufacture maximum acceleration profile (APMMAX), the baseline acceleration profile (APBASE) and/or the loaded acceleration profile (APLOAD), and the degradation factor, the tow estimator112determines an actual tow capacity ratio (RATC) for the vehicle100. If the actual tow capacity ratio (RATC) satisfies (e.g., is greater than or equal to) a tow threshold, the tow estimator112indicates via the infotainment head unit104(e.g., on the center console display and/or the dashboard display). If the actual tow capacity ratio (RATC) does not satisfy the tow threshold, the tow estimator112provides an audio and/or visual warning to the driver (e.g., via the infotainment head unit104). In some examples, the tow threshold is 0.2. In some examples, when the actual tow capacity ratio (RATC) does not satisfy the tow threshold, the tow estimator112calculates an alternative maximum grade for the vehicle100towing the load102and instructs the navigation application to calculate a route to the destination that has a maximum grade less than or equal to the alternative maximum grade.

FIG. 2is a block diagram of the tow estimator112ofFIG. 1. In the illustrated example, the tow estimator112receives input from the yaw and pitch sensor106, the speed sensor108, and a navigation application202executing on the infotainment system of the infotainment head unit104. The tow estimator112provides a tow assessment204that identifies whether the actual tow capacity ratio (RATC) satisfies the tow threshold. The example tow estimator112includes a tow parameters database206, an acceleration calculator208, and a tow assessor210.

The tow parameters database206stores the manufacture acceleration profile (APMAN), the manufacture maximum acceleration profile (APMMAX), and the manufacture maximum tow capacity (TMMAX) of the vehicle100when the vehicle is new. In some examples, the tow parameters database206stores the most recently calculated baseline acceleration profile (APBASE). Additionally, the tow parameters database206stores a table (e.g., Table 1 below) that associates road grade with degradation factors (DF).

TABLE 1Example Degradation Factors (DF) associatedwith Road GradesDegradationRoad GradeFactor (DF)1%0.92%0.83%0.74%0.65%0.56%0.4
For example, on Table 1 above, if the maximum grade of the road segments on the route is 3 percent, the degradation factor (DF) is 0.7.

The acceleration calculator208calculates the baseline acceleration profile (APBASE) and the loaded acceleration profile (APLOAD). The baseline acceleration profile (APBASE) is the average speed as measured by the speed sensor108over time a fixed time when (a) the load102is not connected to the hitch110and (b) the vehicle100is on a flat surface. The loaded acceleration profile (APLOAD) is the average speed as measured by the speed sensor108over time a fixed time when (a) the load102is connected to the hitch110and (b) the vehicle100is on a flat surface.

The tow assessor210calculates the actual tow capacity ratio (RATC). When the load102is not connected to the vehicle100, the tow assessor210calculates the actual tow capacity ratio (RATC) with the baseline acceleration profile (APBASE), as shown in Equation 1 below. When the load102is connected to the vehicle100, the tow assessor210calculates the actual tow capacity ratio (RATC) with the loaded acceleration profile (APLOAD), as shown in Equation 2 below.

When the load102is not connected, the tow assessor210provides the tow assessment204with the current maximum tow capacity (TMAX) over the route provided by the navigation application202, as shown in Equation 3 below.
TMAX=TMMAX*RATC_UEquation 3
For example, if the manufacture maximum tow capacity (TMMAX) is 8,500 pounds (lbs) and the actual tow capacity ratio (RATC) when the vehicle100is not connected to the load102is 0.55, the current maximum tow capacity (TMAX) is 4,675 lbs.

Additionally, when the load102is connected to the vehicle100, the tow assessor210compares the actual tow capacity ratio (RATC) to the towing threshold. In some examples, the tow threshold is 0.2. For example, if the tow threshold is 0.2 and the actual tow capacity ratio (RATC) when the vehicle100is connected to the load102is 0.15, the tow assessor210would determine that the actual tow capacity ratio (RATC) does not satisfy the threshold and that the vehicle100is not able to tow the load via the route provided by the navigation application202. When the load102is connected to the vehicle, the tow assessment204includes (a) instructions for the infotainment head unit104to provide an indication of whether the actual tow capacity ratio (RATC) satisfies the towing threshold, and/or (b) instructions for the navigation application202to calculate a new route with road segments that have a lower maximum grade.

In some examples, when the actual tow capacity ratio (RATC) does not satisfy the threshold, the tow assessor210calculates an alternative maximum road grade to provide to the navigation application202to use when recalculating the route. Initially, the tow assessor210calculates a maximum degradation factor (DFMAX) as shown in Equation 4 below.

DFMAX=Tow_Threshold(1-ABS⁡(APLOAD-APMAN)(APMAN-APMMAX))Equation⁢⁢4
In Equation 4 above, the tow_threshold is the tow threshold. For example, if the tow threshold is 0.2, the loaded acceleration profile (APLOAD) is 40, the manufacture acceleration profile (APMAN) is 100, and the manufacture maximum acceleration profile (APMMAX) is 20, the maximum degradation factor (DFMAX) is 0.8. The tow assessor210then determines the alternative maximum road grade by comparing the maximum degradation factor (DFMAX) to the value on Table 1 above and rounds the maximum degradation factor (DFMAX) up to the nearest road grade. For example, it the maximum degradation factor (DFMAX) is 0.75, the tow assessor rounds up to 0.8. For example if the maximum degradation factor (DFMAX) is 0.8, the alternative maximum road grade is 2 percent. In such an example, the tow assessment204would include instruction to the navigation application202to calculate a route with a maximum road grade of 2 percent.

FIG. 3is a block diagram of the electronic components300of the vehicle100ofFIG. 1. In the illustrated example, the electronic components300include the infotainment head unit104, an on-board computing platform302, sensors304, a global positioning system (GPS) receiver306, and a vehicle data bus308.

The on-board computing platform302includes a processor or controller310and memory312. In the illustrated example, the on-board computing platform302is structured to include tow estimator112. Alternatively, in some examples, the tow estimator112may be incorporated into another electronic control unit (ECU) (e.g., an advanced driving assistance system, etc.) with its own processor and memory. The processor or controller310may be any suitable processing device or set of processing devices such as, but not limited to: a microprocessor, a microcontroller-based platform, a suitable integrated circuit, one or more field programmable gate arrays (FPGAs), and/or one or more application-specific integrated circuits (ASICs). The memory312may be volatile memory (e.g., RAM, which can include non-volatile RAM, magnetic RAM, ferroelectric RAM, and any other suitable forms); non-volatile memory (e.g., disk memory, FLASH memory, EPROMs, EEPROMs, memristor-based non-volatile solid-state memory, etc.), unalterable memory (e.g., EPROMs), read-only memory, and/or high-capacity storage devices (e.g., hard drives, solid state drives, etc). In some examples, the memory312includes multiple kinds of memory, particularly volatile memory and non-volatile memory.

The memory312is computer readable media on which one or more sets of instructions, such as the software for operating the methods of the present disclosure can be embedded. The instructions may embody one or more of the methods or logic as described herein. In a particular embodiment, the instructions may reside completely, or at least partially, within any one or more of the memory312, the computer readable medium, and/or within the processor310during execution of the instructions.

The sensors304may be mounted to measure properties around the exterior of the vehicle100. Additionally, some sensors304may be mounted inside the cabin of the vehicle100or in the body of the vehicle100(such as, the engine compartment, the wheel wells, etc.) to measure properties in the interior of the vehicle100. Some of the sensors304may be mounted around the body of the vehicle100to monitor the external area around the vehicle100. For example, the sensors304may include accelerometers, odometers, cameras, range detection sensors (e.g., RADAR, LiDAR, ultrasonic, infrared, etc.), tachometers, roll sensors, microphones, tire pressure sensors, and biometric sensors, etc. In the illustrated example, the sensors304include the yaw and pitch sensor106, the speed sensor108, and the hitch connector114.

The GPS receiver306provides the current coordinates of the vehicle100. The navigation application202uses the coordinates to calculate a route from the current location of the vehicle100to the destination input into the navigation application202. While the term “GPS” is used, the GPS receiver306may be compatible with any global navigation satellite system, such as GLONASS, Galileo, and/or BeiDou.

The vehicle data bus308communicatively couples the infotainment head unit104, the on-board computing platform302, the sensors304, and the GPS receiver306. In some examples, the vehicle data bus308includes one or more data buses. The vehicle data bus308may be implemented in accordance with a controller area network (CAN) bus protocol as defined by International Standards Organization (ISO) 11898-1, a Media Oriented Systems Transport (MOST) bus protocol, a CAN flexible data (CAN-FD) bus protocol (ISO 11898-7) and/a K-line bus protocol (ISO 9141 and ISO 14230-1), and/or an Ethernet™ bus protocol IEEE 802.3 (2002 onwards), etc.

FIG. 4is a flowchart of a method to estimate the tow capacity of the vehicle100ofFIG. 1that may be implemented by the electronic components300ofFIG. 3. The method ofFIG. 4begins, for example, when an ignition switch of the vehicle100is set into an “ON” position. Initially, at block402, the tow estimator112determines whether the load102is attached. The tow estimator112determines whether the load102is attached via the hitch connector114and/or a rear-facing camera. If the load102is attached, the method continues to block410. Otherwise, if the load102is not attached, the method continues to block404.

At block404, the tow estimator112determines whether the vehicle100has experienced a recalibration event. In some examples, the recalibration events are based on (a) mileage (e.g., every 2,000 miles, every 5,000 miles, etc.), (b) a period of time (e.g., every six months, every year, etc.), or (c) a maintenance event (e.g., an oil change, a tire relation, engine maintenance, etc.). If a recalibration event has occurred, the method continues at block406. Otherwise, if a recalibration event has not occurred, the method ends. At block406, the tow estimator112determines the baseline acceleration profile (APBASE). In some examples, the tow estimator112(i) takes several (e.g., two, three, etc.) measurements of the acceleration of the vehicle100from a zero speed to 40 miles per hour on a flat surface during a driving session, and (ii) averages the measurements. At block408, the tow estimator112stores the baseline acceleration profile (APBASE) in the tow parameters database206.

At block410, the tow estimator112determines the loaded acceleration profile (APLOAD). In some examples, the tow estimator112(i) measures the acceleration of the vehicle100from a zero speed to a target speed on a flat surface. In some examples, the tow estimator112requests, via the infotainment head unit104, that the driver accelerate the vehicle100to the target speed on the flat surface. In some such examples, the tow estimator112may request that the vehicle100with the load102attached be accelerated several times so that the tow estimator112can average the acceleration measurements. At block412, the tow estimator112generates the tow assessment204based on the loaded acceleration profile (APLOAD) determines at block410and a route calculated by the navigation application202. In some examples, to generate the tow assessment204, the tow estimator (a) calculates the actual tow capacity ratio (RATC) in accordance with Equation 2 above, and (b) compares the actual tow capacity ratio (RATC) to the tow threshold.

At block414, the tow estimator112determines whether the actual tow capacity ratio (RATC) satisfies (e.g., is greater than or equal to) the tow threshold. If the actual tow capacity ratio (RATC) satisfies the tow threshold, the method continues at block416. Otherwise, if the actual tow capacity ratio (RATC) does not satisfy the tow threshold, the method continues at418. At block416, the tow estimator112provides, via the infotainment head unit104an audio and/or visual confirmation that the vehicle100can tow the load102via the route. At block418, the tow estimator112provides, via the infotainment head unit104an audio and/or visual confirmation that the vehicle100cannot tow the load102via the route. At block420, the tow estimator112instructs the navigation application to202to determine a new route to the destination. In some examples, the tow estimator112provides an alternate maximum grade to determine the maximum grade that the road segments of the new route may have. In some such examples, the alternate maximum grade is calculated in accordance with Equation 4 above.

The flowchart ofFIG. 4is representative of machine readable instructions stored in memory (such as the memory312ofFIG. 3) that comprise one or more programs that, when executed by a processor (such as the processor310ofFIG. 3), cause the vehicle100to implement the example tow estimator112ofFIGS. 1, 2, and 3. Further, although the example program(s) is/are described with reference to the flowchart illustrated inFIG. 4, many other methods of implementing the example tow estimator112may alternatively be used. For example, the order of execution of the blocks may be changed, and/or some of the blocks described may be changed, eliminated, or combined.