Window object detection with start-up compensation

Abstract: A window obstruction identification system (20) is tailored to better identify obstructions at start-up. The limit (38) at start-up is set based upon the first peak value (30) moving in a direction away from the direction expected for an obstruction. In the case of monitoring speed, the limit (38) is set based upon the first upper peak (30). The limit (38) is set to be a scaler far less than 1 times this peak. In this way, the limit (38) does not vary wih the upcoming expected valleys. In the prior art, an obstruction at start-up was sometimes identified as an expected valley, and thus not quickly identified. In a second embodiment, current (64) is monitored. In a current monitored system, it is the first valley (68) which is utilized to set the limit (71). In such a case, the valley (68) is multiplied by a scaler which is greater than 1. The disclosed system also accounts for system hysteresis by setting the scaler value two different values based upon prior movement if the system is subject to significant hysteresis.

Description: BACKGROUND OF THE INVENTION This invention relates to a method of detecting obstruction in the path of a moving closure, wherein a detection limit is set for initial start-up to identify obstructions at start-up, and a vehicle closure system. Vehicle closures, such as windows, moonroofs and sunroofs are typically powered by a motor at the request of an operator closure switch. As the closure moves to close an opening in the vehicle cab, there may sometimes be an obstruction in the path of the closure. Such obstructions, such as a passenger's arm, will increase the load on the motor closing the closure, or decrease the speed. Typically, a control system for the closure motor looks at a characteristic such as speed, power or torque, and identifies an obstruction based upon this monitored characteristic should the characteristic change more than a predetermined limit away from a predicted value. Difficulties arise in setting the predicted value or limit to correspond to the particular system dynamics for the closure in the vehicle. Further, other challenges, such as variations to the actual characteristic due to vibration, temperature, etc may vary the monitored characteristic, for a reason other than obstruction. To provide a more accurate indication of an obstruction, some systems have monitored the actual system response, and utilize that monitored system response as an indication of what the true predicted value should be. That is, some form of a "learn" cycle is utilized. These closure systems typically have a start-up response which includes monitoring the start-up changes. Typically, the start-up change would include a first upper peak, and then repeated decaying lower end upper peaks. However, a system that monitors start-up peaks, and utilizes the start-up peaks as a "learned" expected value, will not always provide an accurate indication of an obstruction at start-up. That is, if an obstruction would give rise to a lower value than expected (such as monitoring speed) a lowered value at start-up might be seen as one of the valleys that follow the peak at start-up. EP-A-0,945,954 discloses a method of monitoring the closure of a window comprising the steps of: (i) monitoring a system characteristic during a closure movement; (ii) identifying a first extreme value; and (iii) utilizing the extreme value to set the limit that is utilized through at least a start-up period as a limit; and (iv) continuing to monitor said characteristic, and identifying an obstruction if said monitored characteristic crosses said limit. Furthermore, EP-A-0,945,954 discloses a vehicle closure system comprising: a movable closure; a motor for driving said movable closure, and a control for monitoring operation of said motor; and said control being operable to monitor a characteristic, and identify a first extreme value in said characteristic after starting of movement of said closure, and said control being operable to set a limit for comparison to monitored values. SUMMARY OF THE INVENTION The invention is defined in the independent claims. Preferred embodiments are defined in the dependent claims. In a disclosed embodiment of this invention, an initial value in a direction away from the change in the monitored characteristic which is expected at an obstruction is utilized to set a limit. Thus, in the case of speed, the initial upper value is utilized, and multiplied by a scaler to set a fixed limit for start-up. If the monitored value crosses this fixed limit, then an obstruction is indicated. By utilizing this first upper value, the system will not identify the expected decaying valleys to cross a limit. The system will, however, also be able to distinguish between an obstruction during the start-up time and those expected valleys. In a preferred embodiment, the scaler multiplied by the initial upper maximum peak is selected to be less than the ratio of the first valley divided by the first peak. That is, the scaler is selected to be somewhat less than 1. In this way, a limit during start-up is selected which will identify obstructions even at start-up. This limit can merge into a distinct limit or predetermined value after a short start-up period, or could be utilized during the entire closure. In a system monitoring power, it is the initial valley or minimum value which is utilized to select the limit. In such a case, the scaler is selected to be greater than 1, and also greater than the ratio of the maximum divided by the minimum current value. Finally, an embodiment recognises the effect of system hysteresis. This is a recognition that the system response at start-up will be different dependent on the previous movement of the window. If the previous movement was closing, typically the peaks and valleys tend to be more pronounced than if the previous movement was opening. It is thus proposed to select different scaler values that can be utilized dependent on the last movement. The control will remember the last movement and select the appropriate scaler value to set the appropriate limit. These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of a window system. Figure 2 is a graph of a first embodiment when no object is present. Figure 3 shows a first embodiment when an object is present. Figure 4 shows the effect of on the system characteristic based upon last movement. Figure 5 shows a second embodiment. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Figure 1 shows a system 20 driving a closure member 24 into a frame 22. Motor 26 and a control 28 are shown schematically. As known, an operator closure switch actuates the motor 26 to drive the closure 24. The control monitors a characteristic during this movement and compares monitored values of the characteristic to expected values and a limit. If the limit is crossed by the monitored values, then the control can identify that an obstruction 19 is encountered by the enclosure. If so, the motor is either stopped or reversed. Figure 2 shows a typical system response 29 to a monitored characteristic. The monitored characteristic is speed in this case. As shown, at start-up there is an initial upward peak 30, shown as circle in Figure 1 also, and a corresponding valley 32. The terms "peak" and "valley" are to be understood when compared to the steady state speed characteristic 33 after the start-up. As can be seen, there is a smaller peak 34 and a smaller valley 36. This embodiment sets a limit for the operation, at least during start-up, which is selected by the following equation: Limit = max speed x A That is, the limit equals the maximum speed multiplied by some scaler. A is selected to meet the following equation: A < min speed/max speed (in Figure 2 this is 32/30). The limit is fixed by the maximum value, and does not vary after the first peak is reached. Thus, the limit is shown at 38 in Figure 2. If the limit varied with the actual speed, the limit would look more like the dash draft 40. The limit would thus self-adjust for upcoming valleys, and would also self-adjust for an obstruction. As shown in Figure 3, the system response 46 for operation under an obstruction crosses the limit 38 at point 48. Thus, an obstruction is quickly identified. If the limit were to be varied with the speed, such as shown at 40, the limit would drop off with the dropping speed due to the obstruction. That is, the system would believe by following as a percentage of speed during start-up, that a "valley" would be occurring and would move the limit downwardly, missing the identification of the obstruction until later. In sum, the present invention could be stated as utilizing an initial peak in a value during start-up to set a limit, for the case wherein the peak is in the opposed direction to the movement of the characteristic upon sensing an obstruction. That is, in the Figure 1 embodiment, since an obstruction moves the value downwardly the first upward peak is utilized to set the limit. Figure 4 shows another feature. As shown in Figure 4, a first response has a high peak 52 and a low peak 54. A second response 56 has a much smoother peak 58 and valley 60. Both reach a common steady state value 61. The chart 50 is what would be expected in speed if the previous motion of the window was closing prior to the monitored movement. The chart 56 shows the expected response if the previous motion was opening. An embodiment by recognising the difference in start-up values dependent on the previous motion of the window accounts for a phenomenon called system hysteresis. That is, the previous motion effects the next. A different value of the scaler A will thus perhaps be selected by the control dependent on which previous motion. Thus, the control might store two values of A to be utilized to set the initial limits, with a first value being selected for the previous movement being closing and a second value for the previous movement being opening. As shown in Figure 5, a second embodiment 62 monitors motor current 64. In such a case, when an obstruction is encountered, the motor current increases. The motor current has a first maximum value 66 and a first peak 68. As with the prior embodiment, there are decaying further peaks 70 as in the prior embodiment. In this case, the limit is set to have a peak 72 corresponding to the peak 66. However, after this peak, the rest of the limit is based upon the minimum value 68. In this way, the second peak 70 will not effect the limit. If the second peak 70 were utilized to vary the limit, then an obstruction at the time of the second peak 70 could be identified as simply the next peak, and ignored. As shown, if the corresponding peak 70 were accounted for, there would be a peak 74 in the limit. The line 74 also shows the limit if it were varied with the speed as the speed value varies. However, the limit is instead set by the following equation: limit = min current xA after the first end rush. That is, the limit mentioned is found by multiplying the minimum current by a scaler. A is selected to meet the following equation: A is > max current/min current. Now, a system is provided wherein after the first current end rush, the limit is set based upon the minimum value 66. As should be understood, an obstruction will increase the current, and thus the current would move upwardly above the expected current value 64. By setting the limit, at least during starting, based upon the first lower value 68, the present invention does not identify an obstruction after the value 68 as merely being the next peak, such as peak 70, and adjust the limit based upon this falsely identified "second peak". In sum, the present invention utilizes a limit which is adjusted after a first start-up value in the direction opposed to the direction the characteristic will move in the event an obstruction is encountered. By setting the limit in this way, the present invention is better able to identify an obstruction should one occur at start-up. Preferred embodiments of this invention have been disclosed; however, a worker in this art would recognize that modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.

Claims: A method of monitoring the closure of a window (24) comprising the steps of: (i) monitoring a system characteristic during a closure movement; (ii) identifying a first extreme value in a direction opposed to the direction that would be expected on the change in the characteristic due to an obstruction; and (iii) utilizing the first monitored extreme value multiplied by a scaler A to set the limit (38; 71) that is utilized through at least a start-up period as a limit; and (iv) continuing to monitor said characteristic, and identifying an obstruction if said monitored characteristic crosses said limit. A method as set forth in Claim 1, wherein said monitored characteristic is speed, and said first extreme value is a first maximum value in speed (30), said first maximum value being multiplied by a scaler which is less than 1. A method as set forth in Claim 2, wherein said scaler is selected to be less than the ratio of said first maximum speed divided by a first minimum speed (32) which follows said first maximum speed. A system as set forth in Claim 1, wherein said characteristic is one in which a monitored value will increase if an obstruction is identified, and said first extreme value is a first minimum value (68). A method as set forth in Claim 4, wherein said monitored characteristic is motor current. A method as set forth in Claim 4 or Claim 5, wherein a limit is set which is spaced from a first peak value during the time period corresponding to said first peak value, and then said limit being changed to be said first minimum value multiplied by said scaler after the end of said first peak value. A method as set forth in any preceding Claim, wherein distinct scalers are utilized to set said limit based upon whether the last movement of said closure was closing or opening. A vehicle closure system comprising: a movable closure (24); a motor (26) for driving said movable closure, and a control (28) for monitoring operation of said motor; and said control being operable to monitor a characteristic, and identify a first extreme value in said characteristic after starting of movement of said closure, said first extreme characteristic being defined as the first extreme value in a direction opposed to the change in the characteristic which would be expected when an object (19) is encountered, and said control being operable to set a limit (38; 71) for comparison to monitored values, said limit being set by a scaler multiplied by said first extreme value.

Inventors: TYCKOWSKI JOSEPH, TYCKOWSKI, JOSEPH
Applicants: MERITOR LIGHT VEHICLE TECH, MERITOR LIGHT VEHICLE TECHNOLOGY, LLC
Application year: 2001
Main classification: H02H7
IPC codes: H02H3, E05F15, H02H7