Method of detecting leg-only seat belt path selection using seat belt system

Abstract

A method of detecting an incorrect path selection of a seat belt having a leg belt portion and a shoulder belt portion by an occupant of a vehicle includes detecting movement of the seat belt indicating that the shoulder belt portion is placed on a back of the occupant, and providing an alert indicating an incorrect path selection of the shoulder belt portion of the seat belt if the movement of the seat belt indicates that the shoulder belt portion is placed on the back of the occupant.

Description

Technical Field

[0001] The subject disclosure relates to the field of passenger restraint systems and, more particularly, to a method of detecting usage of a lap belt-only routing of a combined lap belt / shoulder belt seat belt system in a vehicle. Background Art

[0002] Many passenger vehicles, particularly those manufactured after 1968, are equipped with passenger restraint systems. Initially, vehicles were equipped with lap belts. In some cases, an additional, separate shoulder belt may also be provided. The use of a lap belt has been shown to reduce deceleration injuries. As vehicle seating systems evolved, improvements in restraint systems also began to appear. A combined lap belt and shoulder belt including a retractor that responds to deceleration forces was developed and incorporated into the vehicle. The combined lap belt / shoulder belt further reduces deceleration injuries and better connects the occupant to the vehicle, distributing the seat belt load over more structural areas of the occupant's body during a collision.

[0003] Although combined lap / shoulder belts have been shown to reduce deceleration injuries, many people find the shoulder belt portion to be uncomfortable. To avoid the discomfort, some people move the shoulder belt over their heads and behind their backs. In this position, these people rely solely on the lap belt to counteract sudden deceleration. Vehicle restraint systems are designed to work together. In some seating positions, the lap belt and shoulder belt cooperate with passive restraint systems (such as air bags) to reduce deceleration injuries. If the shoulder belt is removed, the vehicle restraint system will not function as designed. Therefore, it is desirable to provide a system that detects and prevents non-use of the shoulder belt in a combined lap / shoulder belt seat belt system. Summary of the invention

[0004] According to a non-limiting example, a method of detecting improper routing of a seat belt having a lap belt portion and a shoulder belt portion by an occupant of a vehicle includes detecting movement of the seat belt indicating that the shoulder belt portion is positioned against the occupant's back, and providing a warning indicating improper routing of the shoulder belt portion of the seat belt if movement of the seat belt indicates that the shoulder belt portion is positioned against the occupant's back.

[0005] In addition to one or more features described herein, detecting movement of the seat belt includes determining whether the seat belt has been withdrawn from a tractor by a length that exceeds an over-the-head threshold length.

[0006] In addition to one or more features described herein, a determination is made as to whether the seat belt has been retracted into the retractor at a rate greater than a retraction speed threshold.

[0007] In addition to one or more features described herein, detecting movement of the seat belt includes determining whether the seat belt has been withdrawn from the retractor by a length that is less than a behind-the-back threshold length.

[0008] In addition to one or more features described herein, detecting that the shoulder belt portion is positioned on the occupant's back occurs when the seat belt length is less than a backside threshold length determined from a minimum seat belt routing length.

[0009] In addition to one or more features described herein, checking that a length-based resetting of the seat belt after movement of the seat belt is detected indicates that the shoulder belt portion is positioned on the occupant's back.

[0010] In addition to one or more features described herein, checking for a length-based reset includes determining whether a change in length of the seat belt is less than a false reset threshold.

[0011] In addition to one or more features described herein, a false reset is indicated if the change in length of the seat belt is less than a false reset threshold.

[0012] In addition to one or more features described herein, after a false reset is indicated, a determination is made as to whether the seat belt has been withdrawn from the retractor by a length exceeding an over-the-head threshold length.

[0013] In addition to one or more features described herein, if the seat belt has been withdrawn from the retractor by a length exceeding an over-the-head threshold length after a false reset is indicated, a determination is made as to whether the length of the seat belt is retracted into the retractor at a selected rate.

[0014] In addition to one or more features described herein, a determination is made as to whether the seat belt has been withdrawn from the retractor by a length that is less than a backrest threshold length.

[0015] In addition to one or more features described herein, checking for a length-based reset includes identifying that a change in length of the seat belt occurs within a duration that is less than a false reset time threshold.

[0016] In addition to one or more features described herein, a shoulder belt portion of the seat belt is indicated for proper routing if the length of the seat belt is below a reset threshold and above a false reset threshold.

[0017] In addition to one or more features described herein, the false reset threshold is recalculated based on the over head threshold length, a minimum payout value when the belt is incorrectly routed, and a reset percentage value after a false reset is detected.

[0018] In addition to one or more features described herein, the overhead threshold length is determined from a minimum seat belt routing length.

[0019] In addition to one or more features described herein, one of sensing the presence of an occupant in a seat associated with the seat belt in the vehicle and sensing a length of the seat belt withdrawn from the retractor exceeds a minimum seat belt routing length.

[0020] In addition to one or more features described herein, vehicle operation is inhibited if a warning indicating improper routing of a shoulder belt portion of a seat belt is active.

[0021] In addition to one or more features described herein, detecting movement of the seat belt includes monitoring a length of the seat belt paid out from the retractor using a first sensor and monitoring whether the seat belt is buckled using a second sensor.

[0022] In addition to one or more of the features described herein, one or more decision flags are set when movement of the seat belt is detected.

[0023] According to a non-limiting example, a vehicle includes a vehicle body including a passenger compartment and a seat arranged in the passenger compartment. The seat includes a seat belt having a lap belt portion and a shoulder belt portion. The seat belt is operably connected to a controller that is programmed to perform the method described herein.

[0024] The above features and advantages and other features and advantages of the present disclosure are apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, advantages and details appear, by way of example only, in the following detailed description, which refers to the accompanying drawings, in which:

[0026] Figure 1 is a left side view of a vehicle including a seat belt with a lap belt, a shoulder belt, and a lap belt use only detection system according to a non-limiting example;

[0027] Figure 2 According to a non-limiting example, Figure 1 a left side view of a seat of a vehicle depicting a seat belt having a lap belt, a shoulder belt, and a lap belt use only detection system;

[0028] Figure 3 is a block diagram illustrating various hardware components of a lap belt use-only detection system according to a non-limiting example;

[0029] Figure 4 is a flow chart illustrating a method of detecting lap-only seatbelt usage according to a non-limiting example;

[0030] Figure 5 is a graph and formula depicting an upper head threshold calculation according to a non-limiting example;

[0031] Figure 6 are graphs and formulas depicting threshold calculations behind non-limiting examples;

[0032] Figure 7 is a formula depicting a false reset threshold calculation according to a non-limiting example;

[0033] Figure 8 is a flow chart illustrating an optional short duration check for determining whether lap belt routing detection occurred too quickly according to another aspect of a non-limiting example; and

[0034] Fig. 9 is a flow chart illustrating a method of detecting lap belt usage only according to another aspect of a non-limiting example. DETAILED DESCRIPTION

[0035] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or use. It should be understood that throughout the drawings, corresponding reference numerals represent identical or corresponding components and features. As used herein, the term module refers to a processing circuit, which may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality.

[0036] According to a non-limiting example, the vehicle Figure 1 The vehicle 10 is generally indicated at 10. The vehicle 10 includes a body 12 supported on a plurality of wheels 16. The body 12 includes a passenger compartment 20, and a plurality of seats, such as 22, are arranged in the passenger compartment 20. The seat 22 is positioned behind an instrument panel 26. A steering wheel 30 is arranged between the seat 22 and the instrument panel 26. The seat 22 includes a seat base 32 ( Figure 2 ) and a seat back 34 supporting a headrest 36.

[0037] refer to Figure 2, when the occupant is in the seat 22, a seat belt 38 including a lap belt portion 39 extends through the seat base 32. The seat belt 38 also includes a shoulder belt portion 42. A retractor mechanism 44 including a pretensioner 46 supports the seat belt 38. The retractor mechanism 44 is mounted to, for example, a "B" pillar 50 of the vehicle body 12. In a non-limiting example, the vehicle 10 includes a seat belt monitoring system 60 that performs multiple checks to determine whether the seat belt 38 is buckled and also to determine whether the shoulder belt portion 42 has been manipulated behind the passenger. At this point, it should be understood that the seat belt monitoring system 60 begins monitoring the seat belt 38 upon receiving a signal indicating, for example, that the seat 22 is occupied and the seat belt 38 is buckled.

[0038] Reference Figure 3 , the seat belt monitoring system 60 includes a controller 64 having a central processing unit (CPU) 66, a non-volatile memory 68 storing control logic for monitoring the seat belt 38, and a seat belt monitoring module 70. The seat belt monitoring system 60 is connected to a vehicle sensor 72 that indicates the status of the vehicle 10 (power on / off, door open / closed, vehicle in drive mode), a seat presence sensor 74 that detects the presence of an occupant in the seat 22, a buckle sensor 76 that checks whether the seat belt 38 is buckled, and a seat belt payout sensor 78 that measures the length of the seat belt 38 unwound from the retractor mechanism 44. The number and location of the sensors can vary. For example, the seat presence sensor 74 can be located within the seat 22 or remotely located. The seat belt monitoring system 60 can also be connected to a warning output 80 and a vehicle output 82, the warning output 80 signals to the occupant that the seat belt 38 is incorrectly routed, and the vehicle output 82 is configured to prevent or inhibit operation of the vehicle 10 until the signal from the warning output 80 has been resolved.

[0039] Now refer to Figure 4 , which describes a method 90 for monitoring the seat belt 38 implemented by control logic stored in the non-volatile memory 68. As indicated therein, the method 90 is initiated by the seat belt monitoring system 60 after receiving signals indicating, for example, that the seat 22 is occupied and the seat belt 38 is buckled from at least the seat sensor 74 and the buckle sensor 76. In box 100, the seat belt monitoring module 70 initially performs a path selection length check.

[0040] The routing length check determines whether the length of the seat belt 38 unwound from the retractor mechanism 44 is greater than or equal to a minimum seat belt length threshold stored in the non-volatile memory 68. The minimum seat belt length threshold represents the minimum length required for an occupant to wear the lap belt portion 39 and the shoulder belt portion 42 of the seat belt 38 in a configuration where both the lap belt portion 39 and the shoulder belt portion 42 of the seat belt 38 are routed over the occupant's body. Alternatively, the minimum seat belt length threshold may represent a minimum seat belt length, wherein the methods described herein may provide accurate seat belt routing detection for lap belt-only routing. The length of the seat belt 38 unwound from the retractor mechanism 44 compared to the minimum seat belt length threshold may be referred to as the minimum seat belt routing length, which is the minimum seat belt length unwound from the retractor mechanism 44 within a specified time window after the seat belt 38 is buckled, or the minimum length unwound from the retractor mechanism 44 within the specified time window before the length increases by more than a specified delta amount. If the length of the seat belt 38 unwound from the retractor mechanism 44 is less than the minimum seat belt length threshold, no routing warning and / or callout is issued in box 102, and monitoring continues. If the length of the seat belt 38 unwound from the retractor mechanism 44 is greater than or equal to the minimum seat belt length threshold, a series of determinations are made in box 104.

[0041] In block 104, a determination is made whether the length of the seat belt 38 unwound from the retractor mechanism 44 exceeds an over-the-head threshold based on data stored in the non-volatile memory 68. According to a non-limiting example, the seat belt monitoring module 70 may also check to determine whether the length of the seat belt 38 unwound from the retractor mechanism 44 exceeds the over-the-head threshold and is unwound within a duration equal to or exceeding an over-the-head duration threshold stored in the non-volatile memory 68. The over-the-head duration threshold is a stored value corresponding to a duration taken from the time the over-the-head threshold is exceeded to a point back in time defined by the length of the duration threshold.

[0042] For each occupant's minimum seat belt path length, an overhead threshold may be determined. Figure 5 The overhead threshold is determined by line 106 shown in FIG. 1 , which is located above the passenger's head based on the sample length when the seat belt passes over the passenger's head. Figure 5 on the chart. Figure 5The graph in shows the minimum seat belt routing length on the horizontal axis (which is the minimum seat belt length within a specified time window after the seat belt is buckled, or the minimum length within the specified time window before the length increases by more than a specified delta amount). The graph also shows the overhead length on the vertical axis. Note that the overhead length is the delta length between the minimum seat belt routing length when the shoulder belt is raised over the head.

[0043] When real people put the shoulder belt on their heads, the overhead threshold is calculated from the line equation derived from the measurement data of the real people. In another non-limiting example, when real people put the shoulder belt on the top of their heads, the measurement data can be used because this is the minimum length to move the shoulder belt from the front of their body to the back of their body. The threshold is calculated as follows: overhead threshold = (overhead line slope (slop) × minimum seat belt path selection length) + overhead vertical axis intercept. The overhead line slope is the slope of line 106, and the overhead vertical axis intercept is the vertical axis intercept of line 106. Line 106 is determined so that most of the measurement data points from the study of real people and the belt length that lifts the shoulder belt above their heads fall above the line. Therefore, the overhead threshold is a delta length value above the minimum seat belt path selection length of the passenger. Note that as an alternative to using an equation to associate the overhead threshold with the minimum seat belt path selection length, a lookup table can be used. In addition, if an equation is used, a higher order equation than a linear equation can be used.

[0044] At this point, a determination is made as to whether the length of the seat belt 38 is decreasing at a rate having a negative magnitude that exceeds the retraction velocity threshold stored in the non-volatile memory 68. Still in block 104, the seat belt monitoring module 70 then determines, based on the data stored in the memory 68, whether the length of the seat belt 38 unwound from the retractor mechanism 44 is less than the behind threshold. The behind threshold is calculated from Figure 6 The slope is determined by line 108 shown in FIG. 1 , which has a position based on a sample length of the seat belt 38 when positioned on the back of an occupant.

[0045] Figure 6 The graph in has a minimum seat belt path selection length on the horizontal axis (which is the minimum seat belt length within a specified time window after the seat belt is buckled, or the minimum length within the specified time window before the length increases by more than a specified delta amount). Figure 6This graph shown in also has backside length on the vertical axis. Backside length is the delta length between the minimum seat belt path length when the shoulder belt path is behind the back. The backside threshold is calculated from a line equation derived from fitting measured data from real people when they place the shoulder belt on their backs, as follows: Backside Threshold = (Backside Line Slope x Minimum Seat Belt Path Length) + Backside Length Vertical Intercept.

[0046] The back line slope is the slope of line 106 and the back vertical axis intercept is the vertical axis intercept of line 106. Line 106 is determined so that most of the measured data points from studies of real people and seat belt lengths fall below the line when the shoulder belt is in the back. Therefore, the back threshold is a delta length value below the minimum seat belt path length for the passenger. As an alternative to using an equation that relates the back threshold to the minimum seat belt path length, a lookup table can be used. In addition, if an equation is used, a higher order equation can be used than a linear equation.

[0047] Finally, the seat belt monitoring module 70 determines whether the overhead threshold, the retraction speed threshold, and the behind threshold are all met within a time period less than the event threshold. The event threshold is defined from the time point when the overhead threshold is exceeded to the time point when the behind threshold is passed. Note that within block 104, the retraction speed threshold, the overhead duration threshold, and the event threshold evaluations are optional and may or may not be included.

[0048] At this point, it should be understood that the sequence of events in box 104 can vary. That is, when the passenger moves the shoulder belt portion 42 from the front of the body to the back of the body to create a lap belt path selection condition by using a decision flag in the logic, the decision sequence can occur in the opposite order of the order in which the events occur in real time. In this case, the decision flag can be used as an identifier for a specific set of conditions. For example, the number of detections can be expanded to include additional threshold-based decisions. In box 104, a determination can be made whether the seat belt length is below the back threshold and flag = 1 is set. If flag = 1, a determination can be made whether the seat belt length retraction rate is below the retraction speed threshold and flag = 2 is set. If flag = 2, it can be determined whether the seat belt length is above the head threshold, and if so, flag = 3. When flag = 3, monitoring can continue to box 112.

[0049] If the overhead threshold, the retraction velocity threshold, and the behind threshold are all met for a period of time less than the event threshold, monitoring continues in block 112, and if all criteria are met, an indicator of incorrect path selection is set in block 112. At this point, it should be understood that the event threshold is a period of time stored in the non-volatile memory 68 that corresponds to the statistical calculation time required to accurately determine the overhead threshold, the retraction velocity threshold, and the behind threshold.

[0050] After setting the incorrect routing indicator in box 112, the seat belt monitoring module 70 performs a reset check in box 114. The reset detects whether the seat belt may have moved rearward over the occupant's head and retracted to a length that indicates the shoulder belt is routed around the front of the occupant's torso. During the reset check, the seat belt monitoring module 70 determines whether the seat belt 38 is unwound from the retractor mechanism 44 and then rewound back into the retractor such that the reset threshold is passed when the seat belt is rewound into the retractor (after it has passed the reset threshold when the seat belt was pulled out of the retractor). Typically, the reset threshold is the same as the over head threshold.

[0051] If a reset is detected, the inappropriate path selection indicator is replaced with the appropriate path selection indicator in box 116, and the seat belt monitoring module 70 determines in box 118 whether the reset is a false reset. The seat belt monitoring module 70 determines whether the amount of the seat belt 38 rewound onto the retractor mechanism 44 is less than the false reset threshold. If so, the false reset threshold is updated in box 120, and monitoring returns to box 112. If not, a second series of determinations is made in box 128. The false reset threshold is a stored length that may come from statistical studies to determine when an incorrect path selection is detected when the shoulder belt moves from the back and then returns to the back position, where only the lap belt is worn in both cases. In addition, at box 118, the method can optionally determine whether the false reset occurs within a false reset time threshold. For this optional additional false reset time threshold check, if the length of time from the reset to the correct path selection in box 116 to the time of passing the false reset threshold is less than the false reset time threshold, the method proceeds to box 120. Otherwise, the method proceeds to box 128.

[0052] At block 120, via Figure 7112 to update the false reset threshold. The equation uses three values. One of these is the overhead threshold discussed previously. It also uses a minimum payout value when the seat belt is incorrectly routed, which is stored and continuously updated when the seat belt 38 is detected to be incorrectly routed in box 112. Finally, it uses a reset percentage value, where a value of 100 equals the overhead threshold and 0 equals the minimum payout when the incorrect routing value is selected. Based on these values, the false reset threshold is updated using the following equation: False reset threshold = (reset percentage value / 100) × (overhead threshold-minimum payout value when the seat belt is incorrectly routed) + minimum payout value when the seat belt is incorrectly routed.

[0053] In frame 128, the seat belt monitoring module 70 makes the same determination as that made in frame 104. That is, a determination is made based on the data stored in the non-volatile memory 68 whether the length of the seat belt 38 unwound from the retractor mechanism 44 exceeds the overhead threshold. According to a non-limiting example, the seat belt monitoring module 70 may also check to determine whether the length of the seat belt 38 unwound from the retractor mechanism 44 exceeds the overhead threshold and is unwound for a duration that equals or exceeds the overhead duration threshold stored in the non-volatile memory 68. At this point, a determination is made whether the length of the seat belt 38 is decreasing at a rate having a negative magnitude that exceeds the retraction speed threshold stored in the non-volatile memory 68 when the seat belt 38 is rewound onto the retractor mechanism 44.

[0054] Still in box 128, the seat belt monitoring module 70 then determines whether the length of the seat belt 38 unwound from the retractor mechanism 44 is less than the behind threshold based on the data stored in the memory 68. Finally, the seat belt monitoring module 70 determines whether the overhead threshold, the retraction speed threshold, and the behind threshold are all met within a time period less than the event threshold. Note that the retraction speed threshold, overhead time threshold, and event threshold comparisons are optional and may or may not be performed. If these comparisons in box 128 are met, then the incorrect path selection indicator is set in box 130. If not, another false reset check is performed in box 132.

[0055] After setting the incorrect path selection indicator in frame 130, the seat belt monitoring module 70 performs a reset check in frame 136. During the reset check, the seat belt monitoring module 70 determines whether the seat belt 38 was unwound from the retractor mechanism 44 and then rewound onto the retractor mechanism 44 such that the reset threshold was passed (after the seat belt had passed the reset threshold when it was pulled out of the retractor). If so, the inappropriate path selection indicator is replaced with the appropriate path selection indicator in frame 138, and the seat belt monitoring module 70 determines whether the reset is a false reset in frame 132. If not, the method returns to frame 128.

[0056] In frame 132, the seat belt monitoring module 70 determines whether the seat belt 38 has been rewound onto the retractor mechanism 44 to an amount less than the false reset threshold. If so, the false reset threshold is updated in frame 142 and monitoring returns to frame 130. If not, the second series of determinations is made again in frame 128. Monitoring of the seat belt 38 continues as long as the seat 22 is occupied, the vehicle is active, and the buckle sensor 76 returns a positive output. In addition, at frame 132, the method may optionally determine whether the false reset occurred within a false reset time threshold. For this optional additional false reset time threshold check, if the length of time from reset to correct routing in frame 138 to passing the false reset threshold is less than the false reset time threshold, the method proceeds to frame 142. Otherwise, the method proceeds to frame 128. In this way, the seat belt monitoring system 60 ensures that the seat belt 38 is not worn in a lap belt only routing configuration when the vehicle 10 is in use. When a determination is made that the seat belt 38 is being improperly routed, the seat belt monitoring system 60 may inhibit activation of the vehicle 10 .

[0057] According to a non-limiting example, method 90 may also include: Figure 8 The duration check routine 160 shown. The duration check routine 160 may be performed in a block 164 disposed between the blocks 104 and 112. In block 164, the seat belt monitoring module 70 determines whether the overhead threshold, the retraction speed threshold, and the rear-back threshold are all satisfied within a time period less than the short duration threshold from the buckle time. In other words, the seat belt monitoring module 70 determines whether the path selection detection in block 104 occurs too quickly so that the reset detection logic does not capture a true reset or a false reset.

[0058] If the seat belt monitoring module 70 determines that the path selection detection duration is less than the short duration threshold, then a potentially incorrect path selection designation is set in frame 168 and the method 90 returns to frame 104 to be rechecked. Alternatively, the method may require unbuckling and then rebuckle the seat belt to reset the approach from the potentially incorrect path selection designation. If the seat belt monitoring module 70 determines that the path selection detection duration is greater than the short duration threshold, then the method 90 proceeds to frame 112 to set the incorrect path selection designation before continuing to check for reset.

[0059] At this point, it should be understood that the method 90 continues to monitor the seat belt 38 and provide an infinite reset check to the occupant. That is, the occupant is provided with an infinite number of opportunities to correct the incorrect routing cycle as additional false routing actions have occurred each time the seat belt 38 is reset to the correct routing. In a non-limiting example, the seat belt monitoring system 60 may alternatively be programmed with the method 178, such as Fig. 9 As shown, the method 178 allows for a single reset by the passenger. In a manner similar to that discussed herein, the method 178 is initiated by the seat belt monitoring system 60 after receiving signals from at least the seat occupancy sensor 74 and the buckle sensor 76 indicating, for example, that the seat 22 is occupied and the seat belt 38 is buckled. In block 190, the seat belt monitoring module 70 performs a path selection length check.

[0060] The routing length check determines whether the length of the seat belt 38 unwound from the retractor mechanism 44 is greater than or equal to a minimum seat belt length threshold stored in the non-volatile memory 68. The minimum seat belt length threshold represents the minimum length required for an occupant to wear the lap belt portion and the shoulder belt portion of the seat belt in a configuration where both the lap belt portion and the shoulder belt portion of the seat belt are routed on the occupant's body. Alternatively, the minimum seat belt length threshold may represent a minimum seat belt length, wherein the methods described herein may provide accurate seat belt routing detection for lap belt routing only. The length of the seat belt 38 unwound from the retractor mechanism 44 compared to the minimum seat belt length threshold may be referred to as the minimum seat belt routing length, which is the minimum seat belt length within a specified time window after the seat belt is buckled or the minimum length within the specified time window before the length increases by more than a specified delta amount. If the length of the seat belt 38 unwound from the retractor mechanism 44 is less than the minimum seat belt length threshold, no routing warning / callout is issued in box 192 and monitoring continues. If the length of the seat belt 38 unwound from the retractor mechanism 44 is greater than or equal to the minimum seat belt length threshold, a series of determinations are made in box 194.

[0061] In frame 194, the seat belt monitoring module 70 makes the same determination as that made in frame 104. That is, a determination is made based on the data stored in the non-volatile memory 68 whether the length of the seat belt 38 unwound from the retractor mechanism 44 exceeds the overhead threshold. According to a non-limiting example, the seat belt monitoring module 70 may also check to determine whether the length of the seat belt 38 unwound from the retractor mechanism 44 exceeds the overhead threshold and is unwound for a duration that equals or exceeds the overhead duration threshold stored in the non-volatile memory 68. At this point, a determination is made whether the length of the seat belt 38 is decreasing at a rate having a negative magnitude that exceeds the retraction speed threshold stored in the non-volatile memory 68 when the seat belt 38 is rewound onto the retractor mechanism 44.

[0062] Still in box 194, the seat belt monitoring module 70 determines whether the length of the seat belt 38 unwound from the retractor mechanism 44 is less than the behind threshold based on the data stored in the memory 68. Finally, the seat belt monitoring module 70 determines whether the overhead threshold, the retraction speed threshold, and the behind threshold are all met within a time period less than the event threshold. Note that the retraction speed threshold, overhead time threshold, and event threshold comparisons are optional and may or may not be performed. If these comparisons in box 194 are met, then the incorrect path selection indicator is set in box 210. If not, then the method returns to box 190.

[0063] After setting the incorrect path selection indicator in box 210, the seat belt monitoring module 70 performs a reset check in box 220. During the reset check, the seat belt monitoring module 70 determines whether the seat belt 38 is unwound from the retractor mechanism 44 and then rewound into the retractor such that the seat belt passes the reset threshold when it is rewound into the retractor (after it has passed the reset threshold when the seat belt is pulled out of the retractor). If so, the inappropriate path selection indicator is replaced with the appropriate path selection indicator in box 240, and the seat belt monitoring module 70 determines whether the reset is a false reset in box 260. If not, the method returns to the incorrect path selection indicator in box 210.

[0064] In frame 260, the seat belt monitoring module 70 determines whether the seat belt 38 has been rewound onto the retractor mechanism 44 to an amount less than the false reset threshold. If so, the false reset threshold is updated in frame 280 and the method returns to frame 210. If not, the method returns to frame 240 with an indication of correct path selection. Monitoring of the seat belt 38 continues as long as the seat 22 is occupied, the vehicle is active, and the buckle sensor 76 returns a positive output. Additionally, at frame 260, the method may optionally determine whether the false reset occurred within a false reset time threshold. For this optional additional false reset time threshold check, if the length of time from the reset to the correct path selection in frame 240 to the time of passing the false reset threshold is less than the false reset time threshold, the method proceeds to frame 280. Otherwise, the method proceeds to frame 240.

[0065] In a manner similar to that discussed herein, method 178 may also include: Figure 8 Duration check routine 160 is shown. Duration check routine 160 may be performed between block 194 and block 210.

[0066] At this point, it should be understood that the non-limiting examples discussed herein provide a method and system for monitoring seat belts for incorrect routing of a shoulder belt. If an incorrectly routed shoulder belt is detected, the occupant is warned and given an opportunity to make corrections. If the shoulder belt remains incorrectly routed, the system can inhibit operation of the vehicle 10.

[0067] The terms "a" and "an" do not indicate a limitation of quantity, but rather indicate the presence of at least one of the referenced item. Unless the context clearly indicates otherwise, the term "or" means "and / or". References to "aspects" throughout the specification mean that a particular element (e.g., a feature, structure, step, or characteristic) described in conjunction with that aspect is included in at least one aspect described herein, and may or may not be present in other aspects. In addition, it should be understood that the described elements may be combined in any suitable manner in the various aspects.

[0068] When an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

[0069] Unless stated to the contrary herein, all test standards are the most current standards in effect as of the filing date of this application or, if priority is claimed, the filing date of the earliest priority application in which the test standards appear.

[0070] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0071] Although the above disclosure has been described with reference to exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted for its elements without departing from its scope. In addition, many modifications may be made to adapt specific circumstances or materials to the teachings of the disclosure without departing from the basic scope of the disclosure. Therefore, it is intended that the disclosure is not limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. A method of detecting improper routing of a seat belt having a lap belt portion and a shoulder belt portion by an occupant of a vehicle, the method comprising: detecting movement of a seat belt indicating that the shoulder belt portion is positioned behind the back of an occupant; as well as If movement of the seat belt indicates that the shoulder belt portion is positioned behind the back of an occupant, a warning is provided indicating incorrect routing of the shoulder belt portion of the seat belt. 2 . The method of claim 1 , wherein detecting movement of the seat belt comprises determining whether the seat belt has been withdrawn from a retractor by a length exceeding a threshold over-the-head length. 3 . The method of claim 2 , further comprising determining whether the seat belt has been retracted into the retractor at a rate greater than a retraction speed threshold.

4. The method of claim 2, wherein detecting movement of the seat belt comprises determining whether the seat belt has been withdrawn from the retractor by a length that is less than a back threshold length.

5. The method of claim 4, wherein the shoulder belt portion is detected to be positioned behind the occupant when the seat belt length is less than a behind threshold length determined from a minimum seat belt routing length.

6. The method of claim 2 further comprising checking for length-based resetting of the seat belt after detecting movement of the seat belt indicating that the shoulder belt portion is positioned behind the back of an occupant. 7 . The method of claim 6 , wherein checking for a length-based reset comprises determining whether a change in length of the seat belt is less than a false reset threshold. 8 . The method of claim 7 , wherein checking for a length-based reset comprises identifying that a change in length of the seat belt occurs within a duration that is less than a false reset time threshold.

9. The method of claim 7 further comprising indicating a shoulder belt portion of a correct routing of the seat belt if the length of the seat belt is below the reset threshold and above the false reset threshold.

10. The method of claim 7, further comprising recalculating the false reset threshold based on the over head threshold length, a minimum payout value when the seat belt is incorrectly routed, and a reset percentage value after a false reset is detected.

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