Methods to prevent wheel slip in an autonomous floor cleaner

• US 7,832,048 B2
• Filed: 04/10/2008
• Issued: 11/16/2010
• Est. Priority Date: 06/28/2005
• Status: Active Grant

• Current Assignee: SC Johnson & Son Incorporated
• Original Assignee: SC Johnson & Son Incorporated
• Inventors: Cheng, Fukyuen, Chen, Seakee, Jaworski, Thomas, Harwig, Jeffrey L.
• Primary Examiner(s): GUIDOTTI, LAURA COLE
• Application Number:
  US12/100,446
• Publication Number:
  US 20080188984A1
• Time in Patent Office: 950 Days
• Field of Search: 15/3, 153/19, 153/20, 15/98, 700/245, 700/258, 901/1, 901/46, 180/6.5, 118/207, 118/697, 301/5.302, 152/209.26
• US Class Current: 15/320
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00

Abstract

Tread structures, wave motion navigational controls, and ramp up recovery controls are provided to an autonomous floor cleaner to reduce wheel slippage. The floor cleaner delivers liquid to the floor as part of the cleaning process. Wheels on the device are provided with relatively deep peripheral grooves to minimize the contact surfaces of a sprocket wheel and to accommodate the layer of liquid on the floor. In the event of wheel slippage, or to prevent wheel slippage, the device is designed to move forward with a slight side-to-side wave action caused by periodically altering the relative speeds of two drive wheels. There is also provided a slippage recovery mode where the drive wheels shut down or greatly slow when severe slippage is sensed, followed by a slow ramp up of speed.

Claims

1. A robotic device for treating a surface, comprising:

a first wheel having a first tread, the first tread comprising spaced apart grooved sections defining a channel between the grooved sections, the grooved sections including grooves between floor contacting surfaces, the grooves being of a depth exceeding a predetermined depth, the grooved sections being dimensioned such that the floor contacting surfaces are positioned radially outward from an axis of the first wheel beyond any structure in the channel;

a second wheel having a second tread comprising spaced apart grooved sections defining a channel between the grooved sections, the grooved sections including grooves between floor contacting surfaces, the grooves of the second tread being of a second depth exceeding the predetermined depth, the grooved sections of the second tread being dimensioned such that the floor contacting surfaces of the second tread are positioned radially outward from an axis of the second wheel beyond any structure in the channel of the second wheel;

a housing supported by the first wheel and the second wheel;

means for delivering a layer of fluid onto the surface, and

a controller in communication with the means for delivering a fluid, the controller executing a stored program to provide fluid delivery signals to the means for delivering a fluid such that the layer of fluid on the surface has a thickness less than the predetermined depth.

2. The device of claim 1 wherein:

the first tread and the second tread have a sprocket shape.

3. The device of claim 2 wherein:

radial edges of the sprocket shape are rectangular.

4. The device of claim 1 wherein:

the channel of the first tread has a flat bottom.

5. The device of claim 1, further comprising a pump connected to a fluid reservoir as the means for delivering a layer of fluid onto the surface.

6. The device of claim 5, further comprising a sheet material that receives the fluid from the pump and the fluid reservoir as the means for delivering a layer of fluid onto the surface.

7. The device of claim 1, further comprising a first motor that drives the first wheel, a second motor that drives the second wheel, and a means for measuring wheel rotation of the first wheel and the second wheel, the controller in further communication with the first motor, the second motor, and the means for measuring wheel rotation, the controller receiving first wheel rotation signals associated with the first wheel from the means for measuring wheel rotation, the controller receiving second wheel rotation signals associated with the second wheel from the means for measuring wheel rotation, the controller providing first speed signals to the first motor for driving the first wheel, the controller providing second speed signals to the second motor for driving the second wheel,

wherein the controller executes the stored program to:

(i) calculate a first amount of slip for the first wheel from the first wheel rotation signals received from the means for measuring wheel rotation,

(ii) calculate a second amount of slip for the second wheel from the second wheel rotation signals received from the means for measuring wheel rotation,

(iii) when the first amount of slip exceeds a predetermined first value of slip or the second amount of slip exceeds a predetermined second value of slip, provide fluid delivery signals to the means for delivering a fluid such that fluid is not delivered onto the surface.

8. The device of claim 7, further comprising a pump that delivers the fluid to the surface and is in communication with the controller, and

wherein when the stored program provides fluid delivery signals to the means for delivering a fluid such that fluid is not delivered onto the surface, the controller provides fluid delivery signals to the pump such that the fluid is not delivered onto the surface.

9. The device of claim 7, further comprising a cleaning sheet material that delivers the fluid to the surface, and

wherein when the stored program provides fluid delivery signals to the means for delivering a fluid such that fluid is not delivered onto the surface, the controller provides fluid delivery signals such that delivery of the fluid onto the cleaning sheet material is stopped.

10. The device of claim 7, wherein the means for measuring wheel rotation of the first wheel and the second wheel is an encoder.

11. The device of claim 10, wherein:

the controller executes the stored program to;

(vi) pause for a period of time to allow some cleaner to evaporate before further providing first speed signals to start the first wheel or second speed signals to start the second wheel.

12. The device of claim 7, wherein:

the controller executes the stored program to;

(iv) provide first speed signals to the first motor that slow or stop the first wheel, and

(v) provide second speed signals to the second motor that slow or stop the second wheel.

13. A robotic device for treating a surface, comprising:

a first wheel having a first tread and a second wheel having a second tread, the first tread and the second tread having grooves of a depth exceeding a predetermined depth;

a housing supported by the first wheel and the second wheel;

means for delivering a layer of fluid onto the surface, and

a controller in communication with the means for delivering a fluid, the controller providing fluid delivery signals to the means for delivering a fluid such that the layer of fluid on the surface has a thickness less than the predetermined depth

wherein the device further comprises a first motor that drives the first wheel, a second motor that drives the second wheel, and a means for measuring wheel rotation of the first wheel and the second wheel, the controller in further communication with the first motor, the second motor, and the means for measuring wheel rotation, the controller receiving first wheel rotation signals associated with the first wheel from the means for measuring wheel rotation, the controller receiving second wheel rotation signals associated with the second wheel from the means for measuring wheel rotation, the controller providing first speed signals to the first motor for driving the first wheel, the controller providing second speed signals to the second motor for driving the second wheel,

wherein the controller executes a stored program to;

(i) calculate a first amount of slip for the first wheel from the first wheel rotation signals received from the means for measuring wheel rotation,

(ii) calculate a second amount of slip for the second wheel from the second wheel rotation signals received from the means for measuring wheel rotation,

(iii) when the first amount of slip exceeds a predetermined first value of slip or the second amount of slip exceeds a predetermined second value of slip, provide fluid delivery signals to the means for delivering a fluid such that fluid is not delivered onto the surface.

14. The device of claim 13, further comprising a pump that delivers the fluid to the surface and is in communication with the controller, and

wherein when the stored program provides fluid delivery signals to the means for delivering a fluid such that fluid is not delivered onto the surface, the controller provides fluid delivery signals to the pump such that the fluid is not delivered onto the surface.

15. The device of claim 13, further comprising a cleaning sheet material that delivers the fluid to the surface, and

wherein when the stored program provides fluid delivery signals to the means for delivering a fluid such that fluid is not delivered onto the surface, the controller provides fluid delivery signals such that delivery of the fluid onto the cleaning sheet material is stopped.

16. A robotic device for treating a surface, comprising:

a first wheel having a first tread and a second wheel having a second tread, the first tread and the second tread having grooves of a depth exceeding a predetermined depth;

a housing supported by the first wheel and the second wheel;

means for delivering a layer of fluid onto the surface, and

a controller in communication with the means for delivering a fluid, the controller providing fluid delivery signals to the means for delivering a fluid such that the layer of fluid on the surface has a thickness less than the predetermined depth

wherein the device further comprises a first motor that drives the first wheel, a second motor that drives the second wheel, and a means for measuring wheel rotation of the first wheel and the second wheel, the controller in further communication with the first motor, the second motor, and the means for measuring wheel rotation, the controller receiving first wheel rotation signals associated with the first wheel from the means for measuring wheel rotation, the controller receiving second wheel rotation signals associated with the second wheel from the means for measuring wheel rotation, the controller providing first speed signals to the first motor for driving the first wheel, the controller providing second speed signals to the second motor for driving the second wheel,

wherein the controller executes a stored program to;

(i) calculate a first amount of slip for the first wheel from the first wheel rotation signals received from the means for measuring wheel rotation,

(ii) calculate a second amount of slip for the second wheel from the second wheel rotation signals received from the means for measuring wheel rotation,

(iii) when the first amount of slip exceeds a predetermined first value of slip or the second amount of slip exceeds a predetermined second value of slip, provide fluid delivery signals to the means for delivering a fluid such that fluid is not delivered onto the surface,

wherein the means for measuring wheel rotation of the first wheel and the second wheel is an encoder.

17. The device of claim 16, wherein:

the controller executes a stored program to;

(iv) provide first speed signals to the first motor that slow or stop the first wheel, and

(v) provide second speed signals to the second motor that slow or stop the second wheel.

18. The device of claim 16, wherein:

the controller executes a stored program to;

(vi) pause for a period of time to allow some cleaner to evaporate before further providing first speed signals to start the first wheel or second speed signals to start the second wheel.