Vehicle occupant detection

Abstract

Computer programmed to do the following: Receiving a notification that a vehicle door is half open; Receiving sensor data from a rotation rate sensor in a vehicle; Based on the indication that the vehicle door is half-open, determining a time window of interest with respect to the sensor data, wherein the time window of interest is defined by a time interval that is related to when the vehicle door is half-open; and determining a traversal process based on rotation rate sensor data received within the time window of interest, wherein the traversal process includes an entry process of an occupant or an exit process of an occupant.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This patent application claims priority to and all the benefits of U.S. Provisional Patent Application No. 62 / 482,147, filed April 5, 2017, which is incorporated herein by reference. GENERAL STATE OF THE ART

[0002] Vehicle occupancy sensors include seat sensors, seatbelt sensors, and cameras. For example, seat sensors can be embedded in or integral with a seat bottom or seatback and detect weight, pressure, proximity, etc. Seatbelt sensors can detect a locked condition based on the position of a seatbelt clip relative to a seatbelt buckle. A camera and image processing software can be used to map a vehicle's interior and determine whether an occupant is present. BRIEF DESCRIPTION OF THE DRAWINGS Fig.1 is a schematic diagram of a vehicle having an occupant detection system that includes a computer and one or more sensors. Fig. 2 is a perspective view of the vehicle illustrating a vehicle coordinate system. Fig. 3 is a flowchart illustrating a process for determining a traversing action of an occupant. Fig. 4-18 are graphical illustrations of sensor data received by the computer from the one or more sensors. Fig. 19 is a model that can be used by the computer to determine a traversing action of an occupant. Fig. 20-25 illustrate outputs from the computer when executing instructions related to the Fig. 19 model shown. DETAILED DESCRIPTION

[0003] An occupant detection system is described that includes a vehicle computer and one or more vehicle sensors. According to an illustrative example, the computer may be programmed to: receive an indication that a vehicle door is partially open; receive sensor data from a rotation rate sensor in a vehicle; and determine a traversal action based on the indication and the sensor data.

[0004] According to the at least one example set forth above, the indication includes sensor data received via another sensor located on the door.

[0005] According to the at least one example set forth above, the indication is received from a body control module coupled to a plurality of half-open door sensors, each half-open door sensor associated with one of a plurality of vehicle doors.

[0006] According to the at least one example set forth above, the data is received by the computer in response to the indication.

[0007] According to the at least one example set forth above, the computer is further programmed to determine a time window of interest with respect to the sensor data, wherein the time window of interest is defined by a time interval associated with when the vehicle door is half-open.

[0008] According to the at least one example set forth above, the computer is further programmed to determine a rotation indicator from the data, the rotation indicator indicative of the traversal operation.

[0009] According to the at least one example set forth above, the computer is further programmed to determine the traversal operation based on the rotation indicator being greater than a first threshold or less than a second threshold.

[0010] According to the at least one example set forth above, the computer is further programmed to ignore a rotation indicator from the data indicative of the traversal operation if the rotation indicator coincides with an endpoint of the time window of interest or if the rotation indicator is within a threshold time interval of the endpoint.

[0011] According to the at least one example set forth above, the rotation rate sensor is positioned and oriented in the vehicle to measure a roll rate of the vehicle with respect to a longitudinal axis thereof.

[0012] According to the at least one example set forth above, the computer is further programmed to: receive sensor data from a second rotation rate sensor and an accelerometer; and execute dynamic vehicle model instructions using sensor data from the first rotation rate sensor, the second rotation data sensor, and the accelerometer.

[0013] According to the at least one example set forth above, the computer is further programmed to: determine a weight indicator using the model instructions; determine whether the weight indicator is greater than a threshold; and determine the traversal operation if the weight indicator is greater than the threshold.

[0014] According to the at least one example set forth above, the first rotation rate sensor is positioned and oriented in the vehicle to measure the roll rate of the vehicle with respect to a longitudinal axis thereof, the second rotation rate sensor is positioned and oriented in the vehicle to measure the pitch rate of the vehicle with respect to a transverse axis thereof, and the accelerometer is positioned and oriented in the vehicle to measure movement along a vertical axis of the vehicle.

[0015] According to the at least one example set forth above, the traversing operation comprises one of an occupant entry operation or an occupant exit operation.

[0016] According to the at least one example set forth above, the computer is further programmed to increment or decrement a counter based on determining the traversal event, wherein when the computer determines an occupant entry event, the computer is programmed to increment the counter, and wherein when the computer determines an occupant exit event, the computer is programmed to decrement the counter.

[0017] According to the at least one example set forth above, wherein the sensor is part of a roll stability control system in the vehicle.

[0018] According to another illustrative example, a system comprises: a first rotation rate sensor, wherein the first rotation rate sensor is a motion sensing system in a vehicle; and a computer programmed to: receive an indication that a vehicle door is half-open; receive sensor data from the sensor; and determine a traversal action based on the indication and the sensor data.

[0019] According to the at least one example set forth above, the system further includes a half-open door sensor associated with one of a plurality of vehicle doors, wherein the indication is received by the computer via the half-open door sensor.

[0020] According to the at least one example set forth above, the computer is further programmed to determine a time window of interest with respect to the sensor data, the time window of interest being defined by a time interval associated with when the vehicle door is half-open, the computer being further programmed to determine a rotation indicator from the data, the rotation indicator indicative of the traversal event.

[0021] According to the at least one example set forth above, the first rotation rate sensor is positioned and oriented in the vehicle to measure the roll rate of the vehicle with respect to a longitudinal axis thereof, the motion sensing system further comprising a second rotation rate sensor and an accelerometer, the second rotation rate sensor being positioned and oriented in the vehicle to measure the pitch rate of the vehicle with respect to a transverse axis thereof, the accelerometer being positioned and oriented in the vehicle to measure movement along a vertical axis of the vehicle.

[0022] According to the at least one example set forth above, the computer is further programmed to: receive sensor data from the second rotation rate sensor and the accelerometer; and execute dynamic vehicle model instructions using sensor data from the first rotation rate sensor, the second rotation data sensor, and the accelerometer, the computer being further programmed to: determine a weight indicator using the model instructions; determine whether the weight indicator is greater than a threshold; and determine the traversal operation if the weight indicator is greater than the threshold.

[0023] According to the at least one example, a computer programmed to perform any combination of the examples set forth above is disclosed.

[0024] According to the at least one example, a computer program product is disclosed that includes a computer-readable medium storing instructions executable by a computer processor, the instructions including any combination of the instruction examples set forth above.

[0025] Referring now to the figures, wherein like reference numerals indicate like parts throughout the several views, an occupant detection system 10 for a vehicle 12 is shown including a computer 14 that receives sensor data from a plurality of sensors—at least one of the sensors being a rotation rate sensor—and determines, based on this sensor data, whether a user is entering or exiting a cabin 16 of the vehicle 12. The computer 14 may further determine a number of occupants within the cabin 16 using these signals. In at least one example, the sensors are part of an existing on-board motion sensing system 18; accordingly, the computer 14 may determine entry and exit actions (as well as the number of occupants in the vehicle 12) without requiring significant modifications or additional vehicle hardware.For example, the proposed occupant detection system 10 may utilize a set of instructions implemented in software, firmware, or the like to determine vehicle entry and exit operations, thereby minimizing costs.

[0026] According to at least one example, vehicle 12 may be a fully autonomous taxi that charges passengers a taxi fee. The fee may be based at least in part on the number of passengers transported thereby and / or the distance traveled from point to point to transport the passengers. For example, in fully autonomous implementations, vehicle 12 may have neither a human driver nor an attendant traveling with vehicle 12 (e.g., if the driver or attendant is present, the driver or attendant may determine the number of passengers, determine an accurate total fee for the taxi service, etc.). In fully autonomous implementations, computer 14 may be configured to perform such tasks. And, as described below, computer 14 may be programmed to perform other suitable taxi functions.

[0027] In the Fig.1-2, the vehicle 12 is shown as a passenger car; however, the vehicle 12 could also be a truck, a sports utility vehicle (SUV), a motor home, other personal transportation device, or the like, incorporating the occupant sensing system 10. Further, the vehicle 12 may operate in any suitable number of autonomous modes. For example, the vehicle 12 may be operable in a fully autonomous mode (e.g., with Level 5 autonomy) as defined by the Society of Automotive Engineers (SAE) (which has defined Levels 0-5 operation). For example, at Levels 0-2, a human driver monitors or controls much of the driving, often without assistance from the vehicle 12. At Level 0 (“no automation”), for example, a human driver is responsible for all operation of the vehicle.At Level 1 ("Driver Assistance"), the vehicle 12 sometimes assists with steering, acceleration, or braking, but the driver is still responsible for the vast majority of vehicle control. At Level 2 ("Partial Automation"), the vehicle 12 can control steering, acceleration, and braking under certain circumstances without human interaction. At Levels 3-5, the vehicle 12 performs more driving-related tasks. At Level 3 ("Conditional Automation"), the vehicle 12 can handle steering, acceleration, and braking under certain circumstances, as well as monitor the driving environment. However, at Level 3, the driver may occasionally be required to intervene. At Level 4 ("High Automation"), the vehicle 12 can perform the same tasks as at Level 3, but does not rely on driver intervention in certain driving modes.At level 5 (“full automation”), the vehicle 12 can perform all tasks without driver intervention.

[0028] Computer 14 may be a single computer (or multiple computing devices—e.g., shared with other vehicle systems and / or subsystems). Computer 14 may include a processor or processing circuit 22 coupled to memory 24. For example, processor 22 may be any type of device capable of processing electronic instructions, with non-limiting examples including a microprocessor, a microcontroller or controller, an application-specific integrated circuit (ASIC), etc.—to name a few.In general, the computer 14 may be programmed to execute digitally stored instructions that may be stored in the memory 24 and that enable the computer 14 to, among other things, receive sensor data from one or more vehicle sensors; receive an indication that a vehicle door is half-open; determine that a user is entering or exiting the vehicle 12 using at least some of the sensor data; update a counter that tracks the number of occupants in the vehicle cabin 16; and the like.

[0029] The memory 24 may include any non-transitory computer-usable or -readable medium, which may include one or more storage devices or articles. Example non-transitory computer-usable storage devices include RAM (Random Access Memory), ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM) of conventional computer systems, as well as any other volatile or non-volatile media. Non-volatile media include, for example, image and magnetic disks and other permanent storage. Volatile media includes dynamic random access memory (DRAM), which is typically main memory. As discussed above, the memory 24 may store one or more computer program products embodied as software, firmware, or the like (e.g.,software applications).

[0030] According to one example, the sensor data is received from the motion sensing system 18. The system 18 may be configured to receive sensor data from one or more vehicle systems, including, but not limited to, a roll stability control system, an electronic stability control system, an advanced stability control system, an inertial navigation system (e.g., for a fully autonomous vehicle), an anti-lock brake system, the like, or a combination thereof. For example, the system 18 may detect a loss of vehicle roll stability (e.g., due to abrupt steering changes at high speed) and, in response to such detection, automatically apply the vehicle brakes to counteract the roll of the vehicle. The system 18 may include a first accelerometer 26, a second accelerometer 28, a third accelerometer 30, a first rotation rate sensor 32 (e.g.,a roll rate sensor), a second rotation rate sensor 34 (e.g., a yaw rate sensor), a third rotation rate sensor 36 (e.g., a pitch rate sensor), and the motion sensing computer mentioned above. In some examples, all or some of the sensors 26-36 may be grouped into a common cluster (e.g., including a so-called inertial measurement unit (IMU)). The positions of the sensors 26-36 may be distributed or in a central location of the vehicle 12. Whether or not the sensors 26-36 are implemented in a single device, these sensors may each be associated with a first vehicle axis (e.g., the axis labeled "x") extending along a length of the vehicle 12 (e.g., a longitudinal axis along a vehicle centerline), a second vehicle axis (e.g.,the axis labeled "y," which is perpendicular to the x-axis and extends laterally or transversely across the vehicle 12 (e.g., a transverse axis)); and a third vehicle axis (e.g., the axis labeled "z," which is perpendicular to the x- and y-axes (e.g., a vertical axis)). According to one example, an origin of the longitudinal, transverse, and vertical axes coincides with a vehicle center of gravity (CG); however, this is not required (e.g., other origin locations are also possible).

[0031] A rotation rate sensor may be a sensor that provides an electrical, magnetic, optical, or other suitable output based on a change in rotational position (about an axis) per unit time. The rotation rate sensors 32-36 may be gyroscopic sensors, piezoelectric sensors, the like, or any combination thereof. According to at least one example, the rotation rate sensor 32 is positioned and oriented to provide an output regarding rotation about or with respect to the x-axis—e.g., roll about the x-axis. And according to at least one example, the rotation rate sensor 34 is positioned and oriented to provide an output regarding rotation about or with respect to the z-axis—e.g., yaw about the z-axis. And according to at least one example, the rotation rate sensor 36 is positioned and oriented to provide an output regarding rotation about or with respect to the y-axis—e.g.,Pitch about the y-axis. System 18 may also include other sensors and devices not listed here—e.g., including, but not limited to, wheel speed sensors, steering angle sensors, and the like, as are known in the art.

[0032] As in Fig.1—and for illustrative purposes only—a vehicle forward direction (e.g., along the x-axis) may be considered a positive direction, a vehicle starboard side direction (e.g., along the y-axis) may be considered a negative direction, and a vehicle downward direction (e.g., along the z-axis) may be considered a negative direction. For illustrative purposes only, rotation or roll with respect to the x-axis may also be considered a roll in a positive direction if a vehicle port side 42 rolls upward while a vehicle starboard side 44 rolls downward. Similarly, for illustrative purposes only, rotation or pitch along the y-axis may be considered movement in a positive direction if a vehicle front side 46 tilts downward while a vehicle rear side 48 tilts upward.

[0033] As also in Fig.1, the occupant detection system 10 may include other components (besides the computer 14 and the sensors 26-36), including, among others, a vehicle network connection 100 and an electronic control module 110 (shown here, for example, as a body control module (BCM)). The vehicle network connection 100 may include any suitable wired or wireless in-vehicle communications network that enables communication between electronic devices, such as the computer 14, the system 18, the body control module 110, and the like. In at least one example, the connection 100 includes one or more of a controller area network (CAN) bus, Ethernet, a local interconnect network (LIN), a fiber optic connection, or the like. Other examples also exist. For example, the network connection 100 could alternatively or in combination with, for example,a CAN bus may include one or more individual wired or wireless connections.

[0034] The body control module 110 may include a computing device with a processor and memory (not shown). The processor and memory of the BCM 110 may be similar to the processor 22 and memory 24 described above, except that the memory of the BCM 110 may store instructions specific to the BCM 110 that, when executed by the processor of the BCM 110, cause the BCM 110 to perform at least some functions specific to the BCM 110. Non-limiting examples of BCM functions include monitoring and / or controlling electronic accessories in the vehicle 12, such as power windows, power mirrors, a climate control system, a vehicle immobilizer system, vehicle door locks, and the like.In at least one example, the BCM 110 receives sensor data from one or more sensors 121, 122, 123, 124 located on each of the vehicle doors, and this sensor data indicates whether a respective door is at least partially half-open. As explained in more detail below, the computer 14 may determine whether occupants are entering or exiting the vehicle 12 (using at least one of the sensors 26-36) when it is determined that one of the vehicle doors D1, D2, D3, D4 is half-open. Doors D1-D4 are exemplary; in other examples, more or fewer doors may be used.The sensors 121-124 may be proximity sensors, contact sensors, imaging devices, or any other suitable sensors that may be used by the BCM 110, the computer 14, and / or another computing device to determine that a vehicle door is half-open and / or sufficiently open to permit a traversal operation (e.g., an operation in which a user traverses into or out of the vehicle 12). As used herein, a traversal operation includes at least one of an occupant entry operation or an occupant exit operation. As used herein, an occupant entry operation is an event that a vehicle user (e.g., a human) enters or boards a vehicle 12 (e.g., entering the cab 16). Also as used herein, an occupant exit operation is an event that a vehicle user (e.g.,the same or another person) leaves or gets out of the vehicle 12 (e.g. leaving the cabin 16).

[0035] Furthermore, in the description set forth above, computer 14, BCM 110, and system 18 have been described as separate computing devices or systems, each coupled to one another via network connection 100; however, other examples exist. For example, in at least one example, computer 14 and BCM 110 are integral with one another—e.g., are the same device. In other examples, computer 14 could include the hardware and / or functionality of BCM 110, system 18, or any combination thereof.

[0036] Fig.3 illustrates a process 300 for using the occupant detection system 10 to determine whether a user is currently entering or exiting the vehicle 12. The process begins with block 310, where the computer 14 receives digital and / or analog sensor data from one or more of the vehicle sensors 26-36, 121-124. In at least one example, the computer 14 may monitor sensor data from at least the sensors 121-124 for a half-open door, and when the computer 14 receives an indication that at least one of the doors D1-D4 is half-open, the computer may be triggered to monitor sensor data from one or more of the sensors 26-36 to determine whether an occupant entry operation and / or an occupant exit operation has occurred or is currently occurring.

[0037] Thus, according to one example of block 310, computer 14 may receive sensor data from each of sensors 121-124. And, in one example, a digital one ('1') or the like may indicate a state in which the respective door is half-open, whereas a digital zero ('0') or the like may indicate a state in which the respective door is closed. (Of course, the reverse implementation is also possible.) To illustrate block 310, consider the example of sensor 121 (associated with vehicle door D1) sending a digital '1' to computer 14 indicating that door D1 is half-open. Alternatively, or in combination, sensor 121 could send the same signal to BCM 110, which in turn communicates this state to computer 14 via network connection 100.(Note: Hereinafter, sensors 26-36, 121-124 may be described as communicating directly with computer 14, it being understood that the sensor data may pass through other modules and systems before reaching computer 14 - e.g., including, but not limited to, passing through BCM 110 and / or system 18).

[0038] At block 320, the computer 14 may determine whether the state of any of the vehicle doors is half-open. Continuing with the example set forth above, at block 320, the computer 14 determines that the state of door D1 is half-open based on the sensor data from sensor 121 (e.g., a digital '1'). Thus, according to one example, the process 300 proceeds to block 330. Alternatively, if the computer 14 determines at block 320 that the state of all doors D1-D4 is closed, then the process 300 may return and repeat block 310—e.g., continue receiving sensor data as described above.

[0039] In block 330, computer 14 may monitor and / or receive sensor data from at least one of sensors 26-36—e.g., based on the half-open state of the door determined in block 320. Sensor data may be passed through any suitable filter—e.g., a low-pass filter (e.g., this may be performed via a filter circuit (not shown) in computer 14 or via software). Alternatively, or in combination with low-pass filtering in block 330, such filtering could be performed in block 350, as described below.

[0040] Continuing the above example, in block 330, the computer 14 may monitor the sensor data from the roll rate sensor 32 while the half-open door signal (or indication thereof) is high (e.g., a digital '1'). This sensor data may indicate angular velocity relative to a time quantity. Further, this sensor data may be monitored as it is received (e.g., so-called real-time monitoring), stored in the memory 24 for later computer processing, or the like. As described further below, the computer 14 may evaluate sensor data from the sensor 32 to determine if any rotation indicators (RI) are present. Rotation indicators (RI) may be electrical signal spikes (e.g., current or voltage spikes) indicative of a rotation input to the vehicle 12 (e.g.,based on a rotation input to a gyroscopic sensor (such as sensor 32 or the like), as also discussed below. Thus, the rotation indicators (RI) may include a measurable desired signal within an overall electrical signal (e.g., received from sensor 32), wherein the overall electrical signal—filtered or otherwise—comprises the desired signal plus a so-called noise floor—e.g., the desired signal may have an amplitude correspondingly greater than the noise (e.g., have a signal-to-noise ratio of 2:1, 3:1, or the like).

[0041] For illustrative purposes only, the Fig. 4-8 Sensor data from sensors 26-34 indicating that a user is entering the vehicle 12 from a left side (e.g., through door D1 or D3). More specifically, Fig.7 Longitudinal acceleration data along the x-axis (received from sensor 26), illustrated Fig. 6 Lateral acceleration data along the y-axis (received from sensor 28), illustrated Fig. 5 Vertical acceleration data along the z-axis (received from sensor 30), illustrated Fig. 4 Roll rate data with respect to the x-axis (received from sensor 32) and illustrates Fig. 8 Yaw rate data relative to the z-axis (received from sensor 34). Rotation indicators (RI) (e.g. voltage spikes) are in the Fig. 4 and Fig. 8. It is understood that axial acceleration data can also provide corresponding rotation indicators (RI), as shown in the Fig.5-7. In one example of block 330, computer 14 may monitor and / or receive sensor data only from sensor 32—which, for example, measures roll rate data along the vehicle's longitudinal axis (x-axis). In other examples, computer 14 may use sensor data from more than one of sensors 26-36.

[0042] In block 340, which follows block 330, the computer 14 may again determine the state of the vehicle door (e.g., the same door from block 320)—e.g., whether it remains half-open. Continuing the example set forth above, the computer 14 may again determine whether the state of door D1 is half-open based on the sensor data from sensor 121 (e.g., whether the state remains a digital '1'). If the computer 14 determines that the door remains half-open, then the computer 14 returns and repeats block 330 (e.g., continue receiving and / or monitoring sensor data—e.g., from sensor 32, or from sensor 32 and / or any combination of other sensors 26-30, 34-36).

[0043] However, if the computer 14 determines, based on the sensor data from sensor 121, that the state of door D1 is closed (e.g., a digital '0'), then the process 300 proceeds to block 350.

[0044] When the computer ultimately determines that the state of door D1 is closed, the receiving and / or monitoring of block 330 may cease, and the computer 14 may identify a time interval or time window of interest with respect to the sensor data received and / or monitored in block 330. For example, the time window of interest may include sensor data collected from the start, when the state of door D1 was half-open, until the state of door D1 is determined to be closed. It may be a continuous stream of analog data—or, as discussed above, it could be sampled, filtered, and / or the like.It will be appreciated that, for the purposes of the occupancy detection system 100, the computer 14 may reduce the likelihood of false-positive determinations of traversal events by ignoring sensor data from one or more of the sensors 26-36 when each of the vehicle doors D1-D4 is closed.

[0045] In block 350, the computer 14 may determine an increased probability of a traversal event by determining whether at least one of the rotation indicators (RI) is greater than a first threshold (THR1) or less than a second threshold (THR2) during the time window of interest. The thresholds THR1 and / or THR2 may be predetermined, stored in the memory 24, and / or based on various criteria (e.g., vehicle criteria (e.g., vehicle make, model, suspension system, etc.) and / or vehicle user criteria (e.g., mass, size, etc.)). Furthermore, the first and second thresholds THR1, THR2 may be specific to a particular vehicle door—e.g., THR1 for door D1 may differ from THR1 for door D3 (or door D2 or door D4), etc. Thus, in at least one example, the computer memory 24 stores a number of different first and second thresholds.

[0046] More specifically, if at block 350 a rotation indicator (RI) is greater than threshold THR1 or less than threshold THR2, then process 300 may proceed to block 390. If the rotation indicator(s) (RI) associated with the time window of interest is / are not greater than threshold THR1 or less than threshold THR2 (or no rotation indicators (RI) are determined at all in the time window of interest), then process 300 may return and repeat block 310. For example, the absence of rotation indicators (RI) during a time window of interest could indicate that a vehicle door D1-D4 was opened, but no user traversed the doorway.

[0047] The Fig.Figures 9-16 are examples illustrating rotation rate data 130 from roll rate sensor 32 for different conditions during exemplary time windows of interest—e.g., when the respective door state was specified as half-open. In each figure, a digital signal 132 is shown indicating the time window of interest (and overlapping rotation rate data 130). Fig. Figure 9 illustrates rotation rate data associated with an occupant entering through door D1 and a rotation indicator (RI) less than a second threshold THR2. For illustrative purposes only, THR2 is -0.30 volts (V) here (however, any value correspondingly greater than system noise 134 (e.g., vehicle driveline noise) may be used instead for door D1 or any other vehicle door). Fig.10 illustrates rotation rate data associated with an occupant entering through door D2 and a rotation indicator (RI) greater than a first threshold THR1. For illustrative purposes only, THR1 here is +0.30 volts (V) (however, any value correspondingly greater than system noise 134 may be used instead for door D2 or any other vehicle door). Fig. 11 illustrates rotation rate data associated with an occupant entering through door D3 and a rotation indicator (RI) that is less than a second threshold THR2. And Fig. Figure 12 illustrates rotation rate data associated with an occupant entering through door D4 and a rotation indicator (RI) greater than a first threshold THR1. With respect to the Fig.12, it should be noted that the rotation indicator (RI) may not be as characteristic as the rotation indicators (RI) shown in the Fig. 9-11 (e.g. the one shown in Fig. 12 have a lower signal-to-noise ratio). During the verification test, which involves collecting the Fig. 9-16, instrumentation equipment was placed on a vehicle seat on the inside of door D4, which is disturbed by the entry of a test occupant; if the equipment were not placed in this way, it is expected that the Fig. 12 would be larger.

[0048] Fig. 13 illustrates rotation rate data associated with an occupant exiting through door D1 and a rotation indicator (RI) greater than a first threshold THR1. Fig.14 illustrates rotation rate data associated with an occupant exiting through door D2 and a rotation indicator (RI) less than a second threshold THR2. Fig. 15 illustrates rotation rate data associated with an occupant exiting through door D3 and a rotation indicator (RI) greater than a first threshold THR1. And Fig. Figure 16 illustrates rotation rate data associated with an occupant exiting through door D4 and a rotation indicator (RI) that is less than a second threshold THR2. Again, it is expected that the Fig. 16 could have been higher if the instrumentation had not been located on the seat adjacent to door D4.

[0049] A summary of exemplary scenarios that can be determined by the computer 14 is set out in the following Table I, which Fig. 9-16. Consequently, the computer 14 may determine whether a traversal operation is an entry operation or an exit operation using a respective half-open door signal (e.g., from sensors 121-124), a time window of interest, one or more rotation indicators (RI), and the first and second thresholds (THR1, THR2). TABLE I Sensor for half-open door Sensor output Rotation indicator value > THR1 Rotation indicator value < THR2 Result See also Sensor 121 (D1) (port side 42) 1 No Yes Entry process Fig. 9 Sensor 122 (D2) (starboard side 44) 0 ---------- ---------- ----------- Sensor 123 (D3) (port side 42) 0 ---------- ---------- ----------- Sensor 124 (D4) (starboard side 44) 0 ---------- ---------- ---------- Sensor 121 (D1) (port side 42) 0 ---------- ---------- ---------- Sensor 122 (D2) (starboard side 44) 1 Yes No Entry process Fig. 10 Sensor 123 (D3) (port side 42) 0 ---------- ---------- ---------- Sensor 124 (D4) (starboard side 44) 0 ---------- ---------- ---------- Sensor 121 (D1) (port side 42) 0 --------- ---------- ---------- Sensor 122 (D2) (starboard side 44) 0 ---------- ---------- ---------- Sensor 123 (D3) (port side 42) 1 No Yes Entry process Fig. 11 Sensor 124 (D4) (starboard side 44) 0 ---------- ---------- ---------- Sensor 121 (D1) (port side 42) 0 ---------- ---------- ---------- Sensor 122 (D2) (starboard side 44) 0 ---------- ---------- ---------- Sensor 123 (D3) (port side 42) 0 ---------- ---------- ---------- Sensor 124 (D4) (starboard side 44) 1 Yes No Entry process Fig. 12 Sensor 121 (D1) (port side 42) 1 Yes No Exit procedure Fig. 13 Sensor 122 (D2) (starboard side 44) 0 ---------- --------- ---------- Sensor 123 (D3) (port side 42) 0 ---------- ---------- ---------- Sensor 124 (D4) (starboard side 44) 0 ---------- ---------- ---------- Sensor 121 (D1) (port side 42) 0 ---------- ---------- ---------- Sensor 122 (D2) (starboard side 44) 1 No Yes Exit procedure Fig. 14 Sensor 123 (D3) (port side 42) 0 ---------- --------- ---------- Sensor 124 (D4) (starboard side 44) 0 ---------- ---------- ---------- Sensor 121 (D1) (port side 42) 0 ---------- ---------- ---------- Sensor 122 (D2) (starboard side 44) 0 ---------- ---------- --------- Sensor 123 (D3) (port side 42) 1 Yes No Exit procedure Fig. 15 Sensor 124 (D4) (starboard side 44) 0 ---------- ---------- ---------- Sensor 121 (D1) (port side 42) 0 ---------- ---------- ---------- Sensor 122 (D2) (starboard side 44) 0 ---------- --------- ---------- Sensor 123 (D3) (port side 42) 0 ---------- ---------- ---------- Sensor 124 (D4) (starboard side 44) 1 No Yes Exit procedure Fig. 16

[0050] The Fig. 17 and Fig. 18 illustrate aspects of Fig. 9 and 13 respectively. For example, Fig. Figure 17 shows the sensor data of sensor 32 before and after a window of interest (WOI). Furthermore, Fig.17 at least one rotation indicator (RI) that should be ignored by the computer 14 - e.g., based on its proximity and / or coincidence with an endpoint 136 at the start (of the WOI) and / or an endpoint 138 at the end (of the WOI). That is, the computer 14 may be programmed with instructions to ignore rotation indicators (RI) outside the time window of interest (WOI) (e.g., before an endpoint 136 at the start and after an endpoint 138 at the end), as well as rotation indicators (RI) that occur within a threshold time interval thereof. For example, the rotation indicator (RI) that is near the endpoint 138 (in Fig.17) may be a result of the movement of door D1 to a closed position. While the sensor data from sensor 32 may have a resolution suitable for determining rotation rates related to the weight of an occupant entering and / or exiting the vehicle 12, it may also be sensitive enough to detect impulses and / or other forces applied to the vehicle 12, such as the closing of a vehicle door. The threshold time interval may be + / - 0.5 seconds from either of the endpoints 136, 138; this is, of course, only an example; other interval values ​​less than or greater than 0.5 seconds may be used instead.

[0051] Fig. 18 shows similar information (as in Fig. 17), except that the sensor data relates to an occupant exiting the vehicle 12 through door D1 (see, for example, Fig.13 and explanation above). Again, rotation indicators (RI) that are determined by the computer 14 to be either outside the time window of interest (WOI) and / or within a threshold time interval of the endpoints 136, 138 can be ignored. Although this is stated in the Fig.17-18, sensor data may be received by the computer 14 that includes instances of multiple rotation indicators (RI) occurring within a single time window of interest (WOI)—where two or more occupants entered the vehicle 12 during the time window, or where two or more occupants exited the vehicle 12 during the time window, or where one or more occupants entered and one or more occupants also exited during the time window, etc. By counting the rotation indicators (RI) that are above the first threshold (THR1) and that are less than the second threshold (THR2) (e.g., as set forth in Table I), the computer 14 may determine the number of occupants within the vehicle 12 at any particular time, as explained below.

[0052] Before an example of block 390 in process 300 ( Fig.3), block 360 is described. In at least one example, block 360 may also follow block 320 (e.g., after a determination by computer 14 that a vehicle door is half-open). Thus, the instructions associated with blocks 360-380 may occur at least partially concurrently with respect to the execution of instructions associated with blocks 330-350.

[0053] Block 360 may be similar to block 330 described above; therefore, it will not be described again in detail. In at least one example of block 360, computer 14 receives data from at least sensor 30 (e.g., measuring movement along the z-axis), sensor 32 (e.g., measuring roll rate with respect to the x-axis), and sensor 36 (e.g., measuring pitch rate with respect to the y-axis). Sensor data from any combination of other sensors (e.g., sensors 26, 28, or 34) may also be used in other examples.

[0054] After block 360, the process 300 continues to block 370. In at least one example, block 370 may be identical to block 340; therefore, it will not be described again here. If the computer 14 determines in block 370 that the door (e.g., door D1) is no longer half-open, the process continues to block 380. If block 370 determines that the door (e.g., D1) of block 320 remains half-open, the process 300 may return and repeat block 360 (e.g., continue receiving and / or monitoring sensor data—e.g., from any combination of sensors 30-36).

[0055] In block 380, the computer 14 determines whether a weight indicator (WI) is greater than a third threshold value (THR3); this is described in detail below. The weight indicator (WI) may be related to the weight of an occupant entering or exiting the vehicle 12. Since an occupant (or vehicle user) may be assumed to have a minimum or threshold weight, the weight indicator (WI) may be used, in one example, to mitigate false-positive determinations of a traversal operation. For example, if the weight indicator (WI) exceeds the threshold value (THR3), the process 300 then proceeds to block 390. If the weight indicator (WI) is less than or equal to the third threshold value (THR3), the process 300 may return and repeat the process 300 from the beginning (e.g., loop back to block 310).

[0056] According to block 380, the computer 14 may be programmed to determine a traversal event (e.g., an occupant entry or exit event) by executing dynamic vehicle model instructions stored in memory 24. This model may be used to confirm or support the determination made in block 350, or it may be used as a standalone process to determine a traversal event. As explained below, at least in the illustrated example, it is used to support a positive determination in block 350 (e.g., block 390 may require that block 350 and block 380 be true to proceed to block 400).

[0057] In the following description, at least some of the modeling instructions may be implemented using Matlab Simulink™; however, this is only an example. Of course, other modeling techniques may be used instead. Fig. 19 shows a schematic diagram of a vehicle model 140, where the mass m represents a mass of the vehicle 12 - e.g., the vehicle 12 is modeled with three degrees of freedom (e.g., translation (Z) along the z-axis, rotation (φ) about the x-axis (roll), and rotation (θ) about the y-axis (pitch). In the corners of the model 140, predetermined positions A, B, C, and D are shown, where the segment AB (e.g., distance B f or B f / 2 + B f / 2) of the front 46 of the vehicle 12 and the segment CD (e.g. distance B r or B r / 2+ B r / 2) corresponds to the rear side 48 of the vehicle 12 (e.g., the segment AC (e.g., distances a and b or a + b) corresponds to the port side 42 and the segment BD (e.g., also distance a + b) corresponds to the starboard side 44).

[0058] The Fig.The model 140 shown in Figure 19 may also include a vertical force F(x, y) that may be exerted on the vehicle 12 by an occupant entering or exiting the vehicle within the boundaries defined by positions A, B, C, and D. Vertically directed forces (corresponding, for example, to the vehicle tires and suspension system) are also modeled—namely, forces F A along the axis -z5, F B along the axis -z6, Fc along the axis -z9 or F D along the -z8 axis where the axes -z5, -z6, -z8, and -z9 are parallel to the z-axis.

[0059] The model can be controlled by the exemplary equations (1) - (7). m⋅Z¨=FA+FB+FC+FD−F Iθ⋅θ¨=b(FC+FD)−a(FA+FB)+x⋅F Iφ⋅φ¨=Br / 2⋅(FC−FD)+Bf / 2⋅(FA−FB)+y⋅F FA=Ks1(−Z5)+C1(−Z˙5) FB=Ks2(−Z6)+C2(−Z˙6) FC=Ks3(−Z9)+C3(−Z˙9) FD=Ks4(−Z8)+C4(−Z˙8)

[0060] In the above equations, Z̈ is the axial acceleration along the z-axis, and Ż (e.g., -Ż5, -z6, -Ż9, -Ż8) refers to axial velocities with respect to it. I θ and I φ are instantaneous moments of inertia about the y-axis (pitching moment of inertia) and the x-axis (rolling moment of inertia), respectively - while θ̈ and φ̈ are angular accelerations about the y-axis and the x-axis, respectively. Furthermore, K S1 , K S2 , K S3 and K S4Spring constants associated with the vehicle tires and the vehicle suspension system, and C1, C2, C3, and C4 may be damping constants associated with the vehicle tires and the vehicle suspension system. Both spring and damping constants are known in the art; these constants may be any suitable values. The positions x and y may define the position at which the force F is applied. Example values ​​of x and y are shown in Table II below. These specific positions may correspond to four different vehicle seats in a test vehicle (e.g., vehicle 12), which may be used to generate the previously illustrated sensor data (e.g., Fig. 4-18). Table II coordinate x y Front left 0,1 -0,5 Front right 0,1 0,5 Rear left -1,3 -0,5 Right rear -1,3 0,5

[0061] Tables III and IV present some illustrative values ​​for some of the other parameters of equations (1) - (7). It is understood that these parameters could be equal to or close to the corresponding parameters of the test vehicle described above; therefore, these parameters are merely examples to illustrate the operation of the dynamic model instructions; other suitable parameters may be used instead. Table III parameter Value Front lane (B f ) 1,6667 (m) rear track (B r ) 1,6708 (m) Center of gravity to front axle a 1,1752 (m) Center of gravity to rear axle b 1,6898 (m) Front left suspension stiffness K s1 100 (kN / m) Front right suspension stiffness K s2 100000 (N / m) Rear left suspension stiffness K s3 100 (kN / m) Right rear suspension stiffness K s4 100000 (N / m) Rolling moment of inertia 1500 (kg m^2) Empty weight (m) 2110 kg Pitching moment of inertia 4321 (kg·m^2) Table IV Movement Damping ratio of the front left suspension Damping ratio of the right front suspension Damping ratio of the left rear suspension Damping ratio of the right rear suspension position C1 C2 C3 C4 Getting in (so-called "shaking") 4500 (N s / m) 4500 (N s / m) 4500 (N s / m) 4500 (N s / m) Exit (so-called "rebound") 16000 (N s / m) 16000 (N s / m) 16000 (N s / m) 16000 (N s / m)

[0062] Using Matlab, the reaction curves 150, 152, 154, 156, which are shown in the Fig.20-23, each using the dynamic model instructions and parameters set forth above, to determine that when the computer 14 executes similar instructions (e.g., according to block 380 of the process 300), the computer 14 could determine whether a user has entered or exited the vehicle 12. In the Fig. 20-23, the generated response curves 150-156 overlay the rotation indicators (RI) within the sensor data received via the roll rate sensor 32.

[0063] According to one example, the model instructions exemplified above may be used to derive transfer function equations from a roll rate response of the vehicle body 12 based on an occupant weight (modeled as a step input), as shown in equations (8) and (9). In the present example, these two equations may refer to door D2; however, these equations are merely examples. Similarly derived transfer function equations may be determined by the computer 14 for an occupant entering or exiting at other doors (e.g., D1, D3, D4, etc.). φ.(s)W(s)=0.0003333 ss2+8.354 s+185.6, Boarding φ.(s)W(s)=−0.0003333 ss2+29.7 s+185.6, get out

[0064] Equations (8) and (9) can be a Laplace transform of the roll rate signal and W(s) may be a Laplace transform of the occupant weight. According to an example of the model instructions, if a start time is set to time (t) = 0, a step response using equations (8) and (9) can then be expressed as equation (10), where γ(t) can be defined as γ(t)={1,t>00,t<0 and where during entry a = 0.0003333, b = 8.354 and c = 185.6 and where during exit a = -0.0003333, b = 29.7, c = 185.6. φ(t˙)=2a4c−b2e−b2tsin(4c−b22t)γ(t)

[0065] The weight (W) of an occupant (e.g. the size of the respective step inputs, as in Fig. 24-25) can be identified by applying the homogeneity of linear time-invariant systems. Fig. 24 illustrates a step response 160 of an occupant entering through door D2 according to the transformations described above. And Fig.Figure 25 illustrates a step response 162 of an occupant exiting through door D2 according to the transformations described above. The properties of linear time-invariant systems are well known to those skilled in the art; therefore, they will not be discussed herein. Thus, at least in this example (e.g., for a specific door), the quantity (e.g., weight indicator (WI)) can be defined by equation (11). WI=ψ(deg / s)57⋅ω(rad / s)⋅19.8, where ψ may be a maximum among the absolute values ​​of the roll rate obtainable from the test vehicle, where ω may be a maximum among the absolute values ​​of the roll rate, but is calculated using equation (10). Of course, equations (8)-(11) may again refer to an occupant entering or exiting through door D2, but the computer 14 may derive and use similar equations for a weight indicator (WI) in connection with an occupant entering or exiting through any of the other doors D1, D3-D4, etc.

[0066] Once the weight indicator (WI) is determined, the computer 14 can enter it in block 380 ( Fig.3) with the predetermined third threshold (THR3). And, as described above, if the weight indicator (WI) is greater than the threshold (THR3), the process 300 may then proceed to block 390. If the weight indicator (WI) is less than or equal to the third threshold (THR3), the process 300 may then return and repeat block 310.

[0067] If, in block 390, both the weight indicator (WI) is greater than the threshold (THR3) and the rotation indicator determined in block 350 is at least one of greater than a first threshold (THR1) or less than a second threshold (THR2), then the process 300 proceeds to block 400. Block 390 may ensure that the rotation indicator (RI) loop of process 300 does not complete without also completing the weight indicator (WI) loop, or vice versa. Thus, if both the rotation and weight indicators do not indicate a traversal operation, the process 300 proceeds accordingly from block 390 to block 330 or block 350 to complete the analysis.

[0068] At block 400, the computer 14 may increment or decrement a previously initialized counter. The counter may include programming logic and / or instructions stored in memory 24 or may be implemented as a circuit, to name a few non-limiting examples. During initialization, the counter may be set to zero (0); initialization may occur, for example, at a manufacturing facility or an authorized service center. For example, if an entry operation is determined, the counter may increment by one (1). And if an exit operation is determined, the counter may decrement by one (1). Of course, in some cases, the counter may increment or decrement by more than one (as explained above—e.g., if multiple rotation indicators (RI) indicate this, as do the weight indicators (WI). Other suitable increments and decrements are also possible.

[0069] Table V below illustrates an example of incrementing and decrementing based on an example of vehicle 12, where vehicle 12 includes four doors D1-D4 leading to four adjacent vehicle seats (e.g., a front left seat, a rear left seat, a front right seat, and a rear right seat). The table shows that computer 14 may increment +1 or -1 accordingly when an entry or exit with respect to one of these doors is determined by computer 14. Table V position Sign of the peak roll rate Positive Negative Position front left / Position rear left Exit (-1) Boarding (+1) Position front right / Position rear right Boarding (+1) Exit (-1)

[0070] After block 400, process 300 may return to block 310 and continue monitoring sensor data from vehicle sensors 26-36, 121-124 as previously described. Alternatively, process 300 may end.

[0071] It should be understood that process 300 may be performed when the vehicle ignition state is ON or OFF. This allows the computer counter to track the number of occupants in each state. Further, it should be understood that the counter may be reset by computer 14 at any suitable time—e.g., by authorized service personnel or even when other vehicle data indicates to computer 14 that vehicle cabin 16 is free of occupants. For example, if a camera or other imaging device determines that cabin 16 is empty (and the computer 14 counter indicates that cabin 16 is occupied by at least one user), then computer 14 may reset the counter. Other suitable reset implementations also exist.

[0072] In other examples, computer 14 may determine a traversing event and / or count occupants without determining both a rotation indicator (RI) and a weight indicator (WI). In at least one example process, only one of the rotation or weight indicators may be determined. For example, the determination of the other indicator may be omitted.

[0073] In another example, the rotation indicator(s) (RI) can be determined, and then the weight indicator (WI) can be determined—e.g., one after the other. Or this order could be reversed. There are other examples as well.

[0074] In at least some examples, the determination of occupant detection, occupant count, occupant weights, etc., by computer 14 may be used to improve the vehicle's moving performance. Or, this type of information may be used to improve the vehicle's fuel economy (e.g., by providing the information to a real-time calibration system of a vehicle's powertrain system). Or, this type of information may be used to improve vehicle emergency services (e.g., by providing the information to a vehicle collision warning system, e.g., in response to a collision or accident). Further, this type of information may be used to alert one or more occupants when an occupant is abandoned or otherwise remains in the vehicle (e.g., once the vehicle has reached its destination—e.g., in taxi implementations).These are just examples; there are other examples as well.

[0075] Thus, an occupant detection system for a vehicle has been described. The system includes a computer that receives sensor data from one or more vehicle sensors. The sensors may include at least one rotation rate sensor. Based on sensor data, the computer is programmed to determine whether an occupant has entered or exited the vehicle. The computer may then increment or decrement a counter as appropriate.

[0076] In general, the described computing systems and / or devices may employ any of several computer operating systems, including, but not limited to, versions and / or variants of the Ford SYNC® application, AppLink / Smart Device Link middleware, the Microsoft® Automotive operating system, the Linux operating system and iOS operating systems distributed by Apple Inc., Cupertino, California, the BlackBerry OS distributed by Blackberry, Ltd., Waterloo, Canada, and the Android operating system developed by Google, Inc. and the Open Handset Alliance or the QNX® CAR platform for infotainment from QNX Software Systems. Examples of computing devices include, without limitation, an on-board vehicle computer, a server, or some other computing systems and / or devices.

[0077] Computing devices generally include computer-executable instructions, where the instructions may be executable by one or more computing devices, such as those listed above. Computer-executable instructions may be programmed as embedded software that may be executed in a so-called real-time operating system. In general, a processor (e.g., a microprocessor) receives instructions, e.g., from memory, a computer-readable medium, etc., and executes those instructions, thereby performing one or more processes, including one or more of the processes described herein. Such instructions and other data may be stored and transmitted using a variety of computer-readable media.

[0078] A computer-readable medium (also referred to as a processor-readable medium) includes any non-transitory (e.g., physical) medium involved in providing data (e.g., instructions) that can be read by a computer (e.g., by a computer's processor). Such a medium may take many forms, including, but not limited to, non-volatile media and volatile media. Non-volatile media may include, for example, optical or magnetic disks and other persistent storage. Volatile media may include, for example, dynamic random-access memory (DRAM), which is typically main memory. Such instructions may be transmitted through one or more transmission media, including coaxial cable, copper wire, and fiber optics, which include the wires that comprise a system bus coupled to a computer's processor.

[0079] Databases, data repositories, or other data stores described herein may include various types of mechanisms for storing, accessing, and retrieving different types of data, including a hierarchical database, a group of files in a file system, an application database in a proprietary format, a relational database management system (RDBMS), etc. Each of these data stores is generally embodied in a computing device employing a computer operating system, such as one of those listed above, and is accessed over a network in one or more possible ways. A file system may be accessed by a computer operating system and may include files stored in various formats.An RDBMS generally uses the structured query language (SQL) in addition to a language for creating, storing, manipulating, and executing stored procedures, such as the PL / SQL language mentioned above.

[0080] In some examples, system elements may be implemented as computer-readable instructions (e.g., software) on one or more computing devices (e.g., servers, PCs, etc.) stored on computer-readable storage media (e.g., disks, memory, etc.) associated therewith. A computer program product may include such instructions stored on computer-readable media for performing the functions described herein.

[0081] The processor is implemented via circuits, chips, or another electronic component and may include one or more microcontrollers, one or more field-programmable gate arrays (FPGAs), one or more application-specific circuits (ASICs), one or more digital signal processors (DSPs), one or more custom integrated circuits, etc. As described below, the processor instructs vehicle components to actuate them according to sensor data. The processor may be integrated into a controller by an electronic control unit.

[0082] The memory (or data storage device) is implemented via circuits, chips, or other electronic components and may include one or more of read-only memory (ROM), random access memory (RAM), flash memory, electrically programmable read-only memory (EPROM), electrically programmable and erasable read-only memory (EEPROM), embedded multimedia cards (eMMC), a hard disk, or any volatile or non-volatile media, etc. The memory may store data collected by the sensors.

[0083] The disclosure has been described in an illustrative manner, and it is understood that the terminology used is intended to be of a descriptive nature rather than a limiting one. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the disclosure may be practiced other than as specifically described.

Claims

[1] Computer programmed to: Receiving an indication that a vehicle door is half open; Receiving sensor data from a rotation rate sensor in a vehicle; based on the indication that the vehicle door is half-open, determining a time window of interest with respect to the sensor data, the time window of interest being defined by a time interval associated with when the vehicle door is half-open; and determining a traversal operation based on rotation rate sensor data received within the time window of interest, wherein the traversal operation comprises an occupant entry operation or an occupant exit operation. [2] The computer of claim 1, wherein the indication comprises sensor data received via another sensor located on the door. [3] The computer of claim 1, wherein the indication is received from a body control module coupled to a plurality of half-open door sensors, each half-open door sensor associated with one of a plurality of vehicle doors. [4] The computer of claim 1, wherein the sensor data is received in response to the indication by the computer. [5] The computer of claim 1, wherein the computer is further programmed to determine a rotation indicator from the data, the rotation indicator indicative of the traversal operation. [6] The computer of claim 5, wherein the computer is further programmed to determine the traversal operation based on the rotation indicator being greater than a first threshold or less than a second threshold. [7] The computer of claim 1, wherein the computer is further programmed to ignore a rotation indicator from the rotation rate sensor data indicative of the traversal operation if the rotation indicator coincides with an endpoint of the time window of interest or if the rotation indicator is within a threshold time interval of the endpoint. [8] The computer of claim 1, wherein the rotation rate sensor is positioned and oriented in the vehicle to measure the roll rate of the vehicle with respect to a longitudinal axis thereof. [9] The computer of claim 1, wherein the computer is further programmed to: receive sensor data from a second rotation rate sensor and an accelerometer; and execute dynamic vehicle model instructions using sensor data from the first rotation rate sensor, the second rotation data sensor, and the accelerometer. [10] The computer of claim 9, wherein the computer is further programmed to: determine a weight indicator using the model instructions; determine whether the weight indicator is greater than a threshold; and determine the traversal operation if the weight indicator is greater than the threshold. [11] The computer of claim 9, wherein the first rotation rate sensor is positioned and oriented in the vehicle to measure the roll rate of the vehicle with respect to a longitudinal axis thereof, the second rotation rate sensor is positioned and oriented in the vehicle to measure the pitch rate of the vehicle with respect to a transverse axis thereof, the accelerometer is positioned and oriented in the vehicle to measure movement along a vertical axis of the vehicle. [12] The computer of claim 1, wherein the computer is further programmed to increment or decrement a counter based on determining the traversal action, wherein when the computer determines an occupant's entry action, the computer is programmed to increment the counter, and wherein when the computer determines an occupant's exit action, the computer is programmed to decrement the counter. [13] The computer of claim 1, wherein the sensor is part of a roll stability control system in the vehicle. [14] System comprising: a first rotation rate sensor, wherein the first rotation rate sensor is associated with a motion detection system in a vehicle; and a computer programmed to: Receiving an indication that a vehicle door is half-open; Receiving sensor data from the first rotation rate sensor; based on the indication that the vehicle door is half-open, determining a time window of interest with respect to the sensor data, the time window of interest being defined by a time interval associated with when the vehicle door is half-open; and Determining a traversal operation based on rotation rate sensor data received within the time window of interest, wherein the traversal operation comprises an occupant entry operation or an occupant exit operation. [15] The system of claim 14, further comprising a half-open door sensor associated with one of a plurality of vehicle doors, wherein the indication is received by the computer via the half-open door sensor. [16] The system of claim 14, wherein the computer is further programmed to determine a rotation indicator from the data, the rotation indicator indicative of the traversal operation. [17] The system of claim 14, wherein the computer is further programmed to determine the traversal operation based on the rotation indicator being greater than a first threshold or less than a second threshold. [18] The system of claim 14, wherein the first rotation rate sensor is positioned and oriented in the vehicle to measure the roll rate of the vehicle with respect to a longitudinal axis thereof, the motion sensing system further comprising a second rotation rate sensor and an accelerometer, the second rotation rate sensor being positioned and oriented in the vehicle to measure the pitch rate of the vehicle with respect to a transverse axis thereof, the accelerometer being positioned and oriented in the vehicle to measure movement along a vertical axis of the vehicle. [19] The system of claim 18, wherein the computer is further programmed to: Receiving sensor data from the second rotation rate sensor and the accelerometer; and executing dynamic vehicle model instructions using sensor data from the first rotation rate sensor, the second rotation data sensor, and the accelerometer, the computer further programmed to: determine a weight indicator using the model instructions; determine whether the weight indicator is greater than a threshold; and determining the traversal operation when the weight indicator is greater than the threshold. [20] The system of claim 14, wherein the computer is further programmed to ignore a rotation indicator from the data indicative of the traversal operation if the rotation indicator coincides with an endpoint of the time window of interest or if the rotation indicator is within a threshold time interval of the endpoint.

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