Control arrangement for a propulsion unit for a self-propelled floor care appliance

• US 20070061058A1
• Filed: 09/26/2006
• Published: 03/15/2007
• Est. Priority Date: 09/30/2003
• Status: Active Grant

• Current Assignee: Techtronic Floor Care Technology Limited (Techtronic Industries Company Limited)
• Original Assignee: Healthy Gain Investments Limited
• Inventors: Miller, Ethan, Gordon, Evan
• Granted Patent: US 7,725,223 B2
• Time in Patent Office: Days
• US Class Current: 701/23
• CPC Class Codes: A47L 5/28 Suction cleaners with handles and nozzles fixed on the casings, e.g. wheeled suction cleaners with steering handle A47L5/24 takes precedence
• CPC Class Codes: A47L 9/009 Carrying-vehicles; Arrangements of trollies or wheels; Means for avoiding mechanical obstacles
• CPC Class Codes: A47L 9/2805 Parameters or conditions being sensed
• CPC Class Codes: A47L 9/2831 Motor parameters, e.g. motor load or speed
• CPC Class Codes: A47L 9/2842 Suction motors or blowers
• CPC Class Codes: A47L 9/2863 Control elements activated by pivoting movement of the upright vacuum cleaner handle
• CPC Class Codes: A47L 9/2889 Safety or protection devices or systems, e.g. for prevention of motor over-heating or for protection of the user
• CPC Class Codes: A47L 9/2894 Details related to signal transmission in suction cleaners
• CPC Class Codes: A47L 9/325 for wheeled suction cleaners with steering handle

Abstract

A self propelled upright vacuum cleaner is provided with a Hall effect sensor to provide a Hall voltage that varies according to the position of a handgrip maintained by the vacuum cleaner. A microprocessor generates a PWM control signal to control the movement of the vacuum based on the magnitude of the Hall voltage with respect to various response characteristics, including a non-linear logistic function. As such, the vacuum cleaner imparts a user-friendly responsiveness to the user during the operation of the vacuum cleaner.

Claims

1. A self-propelled floor care appliance comprising:

a drive motor to propel the floor care appliance over a surface to be cleaned;

a Hall effect sensor positioned in an operative relationship with a handgrip maintained by the floor care appliance, said Hall effect sensor configured to provide a Hall voltage based upon the movement of the handgrip; and

a microprocessor configured to receive said Hall voltage, and to store a response characteristic;

wherein said microprocessor supplies a pulse width modulation (PWM) control signal to said drive motor based upon said Hall voltage and said response characteristic, so as to propel the floor care appliance over the surface to be cleaned.

2. The self-propelled floor care appliance of claim 1, wherein said response characteristic comprises a logistic function.

3. The self-propelled floor care appliance of claim 2, wherein said logistic function is non-linear.

4. The self-propelled floor care appliance of claim 2, wherein said logistic function comprises a hyperbolic tangent function having the formula:

$\tanh <br><br>\left(t\right)=\frac{{\mathrm{e<br><br>}}^t-{\mathrm{e<br><br>}}^{-t}}{{\mathrm{e<br><br>}}^t+{\mathrm{e<br><br>}}^{-t}}.$

5. The self-propelled floor care appliance of claim 4, wherein said hyperbolic tangent function is scaled by a coefficient.

6. The self-propelled floor care appliance of claim 1, further comprising:

a selection switch coupled to said microprocessor to select one of at least two response characteristics maintained by said microprocessor.

7. The self-propelled floor care appliance of claim 1, further comprising:

an H-bridge motor driver coupled between said microprocessor and said motor drive, said H-bridge configured to control said motor drive in accordance with said PWM control signal.

8. A method for controlling the movement of a microprocessor controlled, motor driven vacuum cleaner in accordance with a movable handgrip, comprising:

generating a digitized Hall voltage based upon the position of the handgrip;

providing the microprocessor with a response characteristic;

generating a pulse width modulation (PWM) control signal containing a pulse width modulation output level based on the position of the handgrip and said response characteristic;

controlling the motor in accordance with said PWM control signal, so as to propel the floor care appliance in accordance with the movement of the handgrip.

9. The method of claim 8, wherein said response characteristic comprises a logistic function.

10. The method of claim 9, wherein said logistic function comprises a hyperbolic tangent function having the formula:

$\tanh <br><br>\left(t\right)=\frac{{\mathrm{e<br><br>}}^t-{\mathrm{e<br><br>}}^{-t}}{{\mathrm{e<br><br>}}^t+{\mathrm{e<br><br>}}^{-t}}.$

11. The method of claim 8, wherein said first generating step is performed by an analog-to-digital converter (ADC).

12. The method of claim 8, wherein said response characteristic is represented by a lookup table stored by said processor that associates a plurality of predetermined Hall voltage levels with associated predetermined PWM output levels.

13. The method of claim 12, wherein said response characteristic comprises a logistic function.

14. The method of claim 13, wherein said logistic function comprises a hyperbolic tangent function having the formula:

$\tanh <br><br>\left(t\right)=\frac{{\mathrm{e<br><br>}}^t-{\mathrm{e<br><br>}}^{-t}}{{\mathrm{e<br><br>}}^t+{\mathrm{e<br><br>}}^{-t}}.$

15. The method of claim 12, further comprising:

adjusting the total number of said predetermined Hall voltage levels, so as to alter the values of said predetermined PWM output levels, thus changing the response of said response characteristic.

16. A self-propelled floor care appliance controlled by a moveable handgrip comprising:

a drive motor to control the movement of the floor care appliance;

a Hall effect sensor in operative communication with the handgrip, said Hall effect sensor configured to generate a Hall voltage based on the movement of the handgrip;

a microprocessor coupled to said Hall effect sensor;

a lookup table maintained by said microprocessor, said lookup table associating a plurality of predetermined digital Hall voltage levels with predetermined pulse width modulation (PWM) output levels in accordance with a logistic response characteristic;

wherein said microprocessor outputs a pulse width modulation (PWM) control signal to said drive motor, such that said PWM control signal includes one of said PWM output levels associated with said Hall voltage output by said Hall effect sensor in accordance with said lookup table.

17. The self-propelled floor care appliance of claim 16, wherein said logistic response characteristic comprises a hyperbolic tangent function having the formula:

$\tanh <br><br>\left(t\right)=\frac{{\mathrm{e<br><br>}}^t-{\mathrm{e<br><br>}}^{-t}}{{\mathrm{e<br><br>}}^t+{\mathrm{e<br><br>}}^{-t}}.$

18. The self-propelled floor care appliance of claim 17, wherein said hyperbolic tangent function is multiplied by a coefficient, so as to alter the response of said logistic response characteristic.

19. The self-propelled floor care appliance of claim 16, further comprising:

a response button coupled to said microprocessor, wherein actuation of said response button adjusts the total number of said predetermined digital Hall voltage levels maintained by said lookup table.

20. The self-propelled floor care appliance of claim 19, wherein the magnitude of said predetermined PWM output levels are adjusted based on the total number of predetermined digital voltage levels used.