Methods to prevent wheel slip in an autonomous floor cleaner

• US 7,389,166 B2
• Filed: 06/28/2005
• Issued: 06/17/2008
• Est. Priority Date: 06/28/2005
• Status: Active Grant

• Current Assignee: SC Johnson & Son Incorporated
• Original Assignee: SC Johnson & Son Incorporated
• Inventors: Chen, Seakee, Jaworski, Thomas, Harwig, Jeffrey L., Cheng, Fukyuen
• Primary Examiner(s): Nguyen; Cuong H
• Application Number:
  US11/168,038
• Publication Number:
  US 20060293809A1
• Time in Patent Office: 1,085 Days
• Field of Search: 701/23, 701/26, 700/245, 153/19, 153/401, 153/001, 180/6.5, 180/7.1, 318/568.11
• US Class Current: 701/23
• 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 driven by a first motor;

a second wheel driven by a second motor;

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

means for measuring wheel rotation for the first wheel and the second wheel; and

a controller in 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) provide first speed signals to the first motor that slow or stop the first wheel if the first amount of slip exceeds a predetermined first value of slip, and

(iv) provide second speed signals to the second motor that slow or stop the second wheel if the second amount of slip exceeds a predetermined second value of slip.

2. The robotic surface treating device of claim 1, wherein:

the controller executes a stored program to;

(v) provide further first speed signals to the first motor that increases speed of the first wheel if the first wheel has been slowed or stopped because the first amount of slip has exceeded the predetermined first value of slip, and

(vi) provide further second speed signals to the second motor that increases speed of the second wheel if the second wheel has been slowed or stopped because the second amount of slip has exceeded the predetermined second value of slip.

3. The device of claim 2 wherein:

the speed of the first wheel or the speed of the second wheel is increased at a rate dependent on level of a liquid present on the surface.

4. The device of claim 1 wherein:

the first wheel is stopped if the first amount of slip exceeds the predetermined first value of slip, and

the second wheel is stopped if the second amount of slip exceeds the predetermined second value of slip.

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

a first wheel driven by a first motor;

a second wheel driven by a second motor;

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

means for measuring wheel rotation for the first wheel and the second wheel; and

a controller in 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) provide first speed signals to the first motor that cyclically decreases and increases speed of the first wheel if the first amount of slip has exceeded the predetermined first value of slip, and

(vi) provide second speed signals to the second motor that cyclically decreases and increases speed of the second wheel if the second amount of slip has exceeded the predetermined second value of slip.

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

a first wheel driven by a first motor;

a second wheel driven by a second motor;

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

means for measuring wheel rotation for the first wheel and the second wheel; and

a controller in 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, and

(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 first speed signals to the first motor and provide second speed signals to the second motor such that the device navigates in a wavy pattern.

7. The device of claim 6 wherein:

the first speed signals are provided to the first motor and the second speed signals are provided to the second motor such that relative wheel speed between the left wheel and the right wheel varies in a periodic fashion.

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

a first wheel driven by a first motor;

a second wheel driven by a second motor;

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

means for delivering a fluid onto the surface;

means for measuring wheel rotation for the first wheel and the second wheel; and

a controller in communication with the first motor, the second motor, the means for delivering a fluid, 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, the controller providing fluid delivery signals to the means for delivering a fluid,

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, and

(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.

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

a first wheel driven by a first motor;

a second wheel driven by a second motor;

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

a sheet cleaning material disposed on the device;

means for delivering a fluid onto the sheet cleaning material;

means for measuring wheel rotation for the first wheel and the second wheel; and

a controller in communication with the first motor, the second motor, the means for delivering a fluid, 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, the controller providing fluid delivery signals to the means for delivering a fluid,

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, and

(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 sheet cleaning material.