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Self-propelled lawn mower

  • US 7,117,660 B1
  • Filed: 04/12/2000
  • Issued: 10/10/2006
  • Est. Priority Date: 04/12/2000
  • Status: Expired due to Term
First Claim
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1. A self-propelled robotic lawn mower comprising a chassis, a microprocessor, a plurality of cutting heads each of which comprises a rotating disk with retractable blades, each of said cutting heads being pivotally mounted on a support member by means including a tension elastic member which is integral on the one hand to the device chassis and on the other hand to the cutting head, the device having a self-adapting cutting adjustment system comprising a centralized height control member controlling the height of each of said cutting heads, said control member being operatively associated with an algorithm stored in the microprocessor such that when the lawn mower is started, the microprocessor in conjunction with the centralized height control member controls the cutting heads to lift same through a maximum height, the heads being later progressively lowered as the mower moves while the microprocessor constantly analyses an average rotational speed of the cutting disks so that as long as the average rotational speed is above a predetermined value Vr, which corresponds to the speed of the cutting disks when they cut a grass height not to be exceeded, the microprocessor keeps on controlling the heads to lower the same towards a nominal instruction value, and wherein if the average rotational speed decreases below Vr, lowering of the cutting disks is stopped to be only resumed when the cut resistance decreases, the microprocessor being adapted to control grass height at a predetermined level in a predetermined location throughout the mowing operation.

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