Apparatus for cutting grass

• US 9,173,344 B2
• Filed: 05/29/2012
• Issued: 11/03/2015
• Est. Priority Date: 03/19/2012
• Status: Active Grant

• Current Assignee: Fabrizio Bernini
• Original Assignee: Fabrizio Bernini
• Inventors: Bernini, Fabrizio
• Primary Examiner(s): Berhanu, Samuel
• Assistant Examiner(s): Kebede, Tessema
• Application Number:
  US13/482,220
• Publication Number:
  US 20130241475A1
• Time in Patent Office: 1,253 Days
• Field of Search: 320/108
• US Class Current: 1/1
• CPC Class Codes: A01D 34/008 for automated or remotely controlled operation

Abstract

An apparatus for cutting grass including: a lawn mower equipped with: a movement device for movement of the lawn mower at least inside a cutting area (S), one or more blades for cutting grass in the cutting area (S), a power supply unit for supplying electrical power to one or more of the movement device and the one or more blades; a recharging base for the lawn mower, including at least a first inductive element (E1) and a first control unit associated with the first inductive element (E1) and configured to enable the flow of a certain current (I) in the first inductive element (E1). The lawn mower comprises has a second inductive element (E2) associated with the power supply unit and coupleable to the first inductive element (E1) for a recharging of the power supply unit, and a second control unit. The second control unit is configured to generate a charge signal (CS) representative of a charge level of the power supply unit; transmit the charge signal (CS) to the first inductive element (E1) through the second inductive element (E2). The first control unit is configured to receive the charge signal (CS) through the first inductive element (E1); regulate the current (I) based on the charge signal (CS).

Claims

1. An apparatus for cutting grass comprising:

a robotic lawn mower equipped with;

movement means for movement of said lawn mower at least inside a cutting area (S);

one or more blades for cutting grass in said cutting area (S);

a power supply unit for supplying electrical power to one or more of said movement means and said one or more blades;

wherein the lawn mower moves under normal operating conditions within the cutting area (S), concomitantly activating the blades so as to cut the grass present in the cutting area (S), the movement of the lawn mower taking place according to a path dictated by a pre-established motion algorithm;

a recharging base for said lawn mower, comprising at least a first inductive element (E1) and a first control unit associated with said first inductive element (E1) and configured for making a certain current (I) to flow in said first inductive element (E1);

wherein said lawn mower comprises a second inductive element (E2) associated with said power supply unit and coupleable to said first inductive element (E1) for a recharging of said power supply unit, and a second control unit;

wherein said second control unit is configured to;

generate a charge signal (CS) representative of a charge level of said power supply unit;

transmit said charge signal (CS) to said first inductive element (E1) through said second inductive element (E2);

said first control unit being configured to;

receive said charge signal (CS) through said first inductive element (E1); and

regulate said current (I) based on said charge signal (CS);

a monitoring circuit associated with the power supply unit, configured to monitor the charge level of the power supply unit, enabling a generation of an alert signal (AS) when the charge level drops below a preset threshold, the generation of the alert signal (AS) indicating that a re-entry of the lawn mower to the recharging base is necessary; and

a control unit commanding the movement means so that the lawn mower returns to the recharging base as a function of the generation of the alert signal (AS);

wherein said first control unit is configured to;

operate on said first inductive element (E1) so as to periodically emit pulses of power of a predetermined duration and intensity;

wherein the pulses are generated by bringing the first inductive element (E1) to a condition of saturation and then implementing emission at a maximum power available, whereby following a predetermined time interval a protection circuit intervenes to limit the current flowing into the first inductive element (E1) and thus determines an end of each pulse emitted;

determine a parameter representative of a phase shift between current and voltage following the emission of each one of said pulses;

wherein the phase shift between current and voltage is correlated with the efficiency of a transfer of energy from the recharging base to the lawnmower;

compare said phase shift with reference parameters; and

determine the presence or absence of said lawn mower based on said comparison wherein, when said first control unit determines the presence of said lawn mower, it is configured to;

receive said charge signal (CS); and

regulate said current (I) on the basis of said charge signal (CS), wherein, when said first control unit determines the absence of said lawn mower, it is configured to;

continue emission of said power pulses periodically, until the presence of said lawn mower is determined.

2. The apparatus according to claim 1, wherein a frequency of said charge signal (CS) is representative of the charge level of said power supply unit.

3. The apparatus according to claim 2, wherein a frequency of said charge signal (CS) is proportional to the charge level of said power supply unit.

4. The apparatus according to claim 1, wherein said first control unit is configured to decrease an intensity of said current (I) when there is an increase in the charge level of said power supply unit.

5. The apparatus according to claim 1, wherein said first control unit is configured to:

compare said charge signal (CS) with pre-stored data;

maintain the intensity of said current (I) constant at a first value, if the charge level of said power supply unit is below a first threshold; and

decrease the intensity of said current (I), if the charge level of said power supply unit is above said first threshold.

6. The apparatus according to claim 5, wherein said first control unit is configured to maintain the intensity of said current (I) constant at a second value, which is lower than said first value, if the charge level of said power supply unit is above a second threshold, the latter being higher than said first threshold.

7. The apparatus according to claim 1, wherein said first control unit is configured to:

determine a parameter representative of a phase shift between voltage and current in said first inductive element (E1); and

regulate said current (I) on the basis of said parameter.