Automatic torque calibration for roller shades

Abstract

A method that detects obstacles on a roller shade's travel that create excess torque by sensing the current draw from a motor and method by which the motor can calibrate itself to detect excess torque. During the roller shade's travel, it will record the instantaneous torque being generated at various points. For example, it will store the greatest value in the shade motor's non-volatile memory as the normal operating torque.

Claims

1. A method for controlling a motorized roller shade device, the device including a roller shade fabric, a drive unit, a spline roller, a hem bar, a shade motor, a motor controller, a Hall Effect sensor, and a nonvolatile memory for storing over-current threshold values (OCTH), the method comprising the steps of: waiting for said roller shade fabric to be at a lowest limit; after said roller shade fabric is at the lowest limit, waiting for a command to go to an upper limit; capturing an over-current threshold value (OCTH) auto calibration by calculating the sum of a peak value, a fixed minimum value, and a percentage of an average value in order to determine a replacement value; storing said over-current threshold value (OCTH) auto calibration if there is no (a) over current event and (b) the shade effectively reaches said upper limit; and discarding said over-current threshold value (OCTH) auto calibration if an over current event was detected, wherein said over current event further causes said shade motor to stop and reverse direction by a predetermined number of revolutions thereby removing any built up tension in said roller shade fabric.

2. The method of claim 1, wherein said discarding said over-current threshold value (OCTH) auto calibration if an over current event was detected further comprises: setting said over-current threshold value (OCTH) equal to Zero.

3. The method of claim 1, further comprising the operations of: setting said over-current threshold value (OCTH) equal to Zero whenever said lower limit is changed.

4. The method of claim 1, wherein said predetermined number of revolutions is at least one-half of a revolution.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 is an exploded perspective view of an exemplary motorized roller shade according to an embodiment or the present invention.

(2) FIG. 2 shows a partial block diagram of an exemplary controller for the system of FIG. 1.

(3) FIG. 3 shows the steps of an illustrative method of OCTH auto calibration using the system of FIG. 1.

LIST OF REFERENCE NUMBERS FOR THE MAJOR ELEMENTS IN THE DRAWING

(4) The following is a list of the major elements in the drawings in numerical order. 100 Motorized Roller Shade Device 101 Roller Shade Fabric 104 Drive Unit 105 Spline Roller 106 Exposed Hem Bar 202 Shade Motor 203 Motor Controller 204 NVRAM 205 Interface 206 Control System 207 Hall Effect Sensor 300 OCTH auto calibration method 301 Wait for lower limit step 302 Wait for upper limit command 303 Reach top limit success 304 Store the new OCTH value 305 Discard data from run

DETAILED DESCRIPTION OF THE INVENTION

Mode(s) for Carrying Out the Invention

(5) The preferred embodiment of the present invention is described herein in the context of roller shades, but is not limited thereto, except as may be set forth expressly in the appended claims.

(6) Disclosed are a system and a method for calibrating and controlling movement of a roller shade according to a detected load that is measured during normal operation. During a roller shade's travel, the instantaneous torque being generated at various points is determined. In one embodiment, the greatest value is stored in a non-volatile memory (NVRAM) of shade motor. Generally, the stored value can be considered the normal operating torque. The store value is periodically updated to compensate for any external factors. External factors may include: temperature, humidity, grease viscosity changes, and/or mechanical component wearing.

(7) Initially, the shade is programmed to have a default OCTH value of zero. With an OCTH value of zero movement will not be interrupted in response to a sensed value of current. Put differently, any driver circuit overload protection would come from, for example, some other hardware protection mechanism engineered into the product.

(8) Referring to FIG. 1, motorized roller shade device 100 may include a roller shade fabric 101, drive unit 104, a spline roller 105, and an exposed hem bar 106.

(9) Referring to FIG. 2, shown is an exemplary controller, according to one embodiment. The controller may include a shade motor 202, a motor controller 203, an interface 205, a control system 206, and a Hall Effect sensor 207. The controller may further include a nonvolatile (NVRAM) memory 204 for storing OCTH values. The control system 206 can be connected via a wired connection using a protocol such as Ethernet, or communicate via wireless communication using IR, or RF circuitry.

(10) Referring now to FIG. 3, shown is an exemplary dynamic OCTH calibration method 300. This method can be used for different shaped and sized shades 101. At step 301, the Motorized Roller Shade Device waits for the roller shade fabric 101 to be at the lowest limit (fully closed or lowered). When the roller shade fabric 101 is at the lowest limit, Motorized Roller Shade Device waits for a command to go to the upper limit, step 302, in which the OCTH auto calibration data capture will begin.

(11) While rising towards the upper limit, if there is no over current event and the shade effectively reaches the top limit (step 303), the data will be valid, and the OCTH auto calibration algorithm will proceed to calculate and store the new OCTH value (step 304). If an over current event was detected, the normal handler of this event will be executed, and the auto calibration algorithm will not use the data from this run (step 303.)

(12) In some embodiments, the lower limit can be changed. In these embodiments, adjustment to the OCTH may be needed, for example to compensate for the new amount of torque required to roll the additional fabric. Accordingly, whenever the lower limit is changed, the present OCTH may be invalidated to Zero and may be recalculated properly on the next bottom to top run.

(13) The risk that the shade might encounter an unexpected obstacle and will not stop the motor until the amount of drawn current is high is very low in comparison to the normal expected every day operation of the shade.

(14) The Auto Calibration of the OCTH may be calculated in various ways. New OCTH values can be determined, for example, as a sum of: a peak value; fixed minimum value; and a percentage of an average. Other ways may include accounting for the weight of unrolled roller shade fabric 101 at any given time.

LIST OF ACRONYMS USED IN THE DETAILED DESCRIPTION OF THE INVENTION

(15) The following is a list of the acronyms used in the specification NVRAM Non-volatile memory OCTH Over-Current Threshold IR Infrared RF Radio Frequency

ALTERNATE EMBODIMENTS

(16) Alternate embodiments may be devised without departing from the spirit or the scope of the invention.