Sensor and method of detecting the condition of a turf grass

• US 8,482,736 B2
• Filed: 02/22/2011
• Issued: 07/09/2013
• Est. Priority Date: 08/01/2003
• Status: Expired due to Fees

• Current Assignee: David Franzen, Greg Biggs, John Rada, Jonathan M. Welles, Kevin Ediger, Tanvir Demetriades-Shah
• Original Assignee: David Franzen, Greg Biggs, John Rada, Jonathan M. Welles, Kevin Ediger, Tanvir Demetriades-Shah
• Inventors: Franzen, David, Rada, John, Ediger, Kevin, Biggs, Greg, Welles, Jonathan M., Demetriades-Shah, Tanvir
• Primary Examiner(s): Toatley, Gregory J
• Assistant Examiner(s): Valentin, II, Juan D
• Application Number:
  US13/032,576
• Publication Number:
  US 20110235043A1
• Time in Patent Office: 868 Days
• Field of Search: None
• US Class Current: 356/445
• CPC Class Codes: A01D 34/006 Control or measuring arrangements
• CPC Class Codes: G01N 21/55 Specular reflectivity

Abstract

A method of detecting the condition of a turf grass is described. According to one aspect of the invention, the method comprises steps of attaching an active sensor to a mower; traversing a section of turf grass; and processing the output of the sensor. A device for detecting the condition of turf grass is also disclosed. The device comprises an array of illuminating devices generating a pattern of illuminating light; a detecting device receiving a pattern of reflected light which is coincident with the pattern of illuminating light; a detecting device adapted to detect stray light from the array of illuminating devices; and a feedback loop controlling the array of illuminating devices. A system employing the device is also disclosed.

Claims

1. A device for detecting a condition of turf grass, said device comprising:

an array of LEDs generating a cone of illuminating light;

a photodetector receiving a cone of reflected light which is coincident with said cone of illuminating light;

one or more photodetectors adapted to detect light from said array of LEDs;

a feedback loop controlling said array of LEDs based upon light from said array of LEDs; and

a circuit for providing offset correction of at least one modulation frequency of the LEDs included in said array of LEDs.

2. The device of claim 1 wherein said array of LEDs comprises LEDs having a plurality of modulation frequencies.

3. The device of claim 1 wherein said feedback loop comprises a first demodulator for a first frequency and a second demodulator for a second frequency.

4. The device of claim 1 wherein said circuit for providing offset correction comprises a first offset correction circuit for a first frequency and a second offset correction circuit for a second frequency.

5. The device of claim 1 further comprising a background light subtraction circuit.

6. The device of claim 1 wherein said device detects stray light from said array of illuminating devices.