1 2
of clutch brake assemblies for steering the mower along AUTOMATED LAWN MOWER OR FLOOR the edge of the swath. These clutch brake assemblies are
POLISHER connected for selectively braking and or driving the
wheels of the mower. A sensor and control circuit deBACKGROUND OF THE INVENTION 5 sign is disclosed for guiding the mower along the swath 1. Field of the Invention et*§e w'th a minimum of hunting even with grass is
The present invention relates to automated lawn damp or growing sparsely. U.S. Pat. No. 4,184,559, mowers, and more particularly pertains to a new and which issued to H. Rass on Jan. 22, 1980, discloses a improved automated lawn mower which utilizes obsta- lawn mower with a mechanical sensor and piloting cle sensors and touch grass sensors to control the direc- 10 mechanisms which enable it to pilot itself along the tion of movement of a lawn mower through a computer edge line between the grass already cut and grass not interfaced feedback control of independent wheel drive yet cut, in a fairly straight course, and then to reverse its motors. The conventional forms of automated lawn direction at the end of a run, move itself sideways, mowers heretofore devised require the setting of a towards the uncut grass and proceed with another run. boundary track or indicator around the plot of land to 15 The lawn mower drive wheels are driven by a planetary be mowed. Alternatively, the conventional forms of gear mechanism which is coupled both to the motor and automated lawn mowers require a detailed precise pro- to rotatable sensor brushes mounted ahead of the drive grammed map of the plot of land to be mowed to enable wheels so that the planetary mechanism transmits the mower to follow a proper mowing course. In order power to the drive wheels only when the sensor brushes to overcome the disadvantages of providing a pro- 20 encounter resistance, such as from uncut grass, ahead of grammed lawn plot map or constructing a boundary the drive wheels. The planetary gear mechanism is track indicator, the present invention provides an auto- mounted on a guide frame that is pivotally mounted to mated self propelled lawn mower which utilizes infra- t^e wheel frame so as to engage a first of two red obstacle detectors in conjunction with cut or uncut COUnter rotating gears linked on the wheel frame to the grass sensors to provide feedback control to indepen- 25 drive wheels. Forward impact against the guide frame dent wheel drive motors for steering the mower on a causes it tQ pivotally rock so ^ t0 engage the second of
proper course. the counter rotating gears to reverse direction of travel
2 Description of the Prior Art of the lawn mowef u s Pat No 4 347 908> which
Various types of automated lawn mowers are known ... tQ R ABdmfm on s t 7 1982 discloses a self
in the prior art. A typical example:<rf^uchtan automated 30 d ^ tQ &
lawn mower is to be found m U.S. Pat. No. 3,550,714, 1 5 n J * 1. jur«- 1- j
.... . . o r> ii- T-> ->n mm -m.- plot of land to be mowed by following a lme arranged
which issued to S. Bellinger on Dec. 29, 1970. This v „i_ 1 j • J * ■ J. A 1. • 1
. . „„ „„ °t , ,f „„„_ over the land m a predetermined manner. A mechanical
patent discloses an automated sell propelled mower „ „ , .r . ., , it_ ,
which operates on the principle of random motion *> ower nanism ,s providedonthe lawn mower for
within a boundary. The boundary is established by a 35 following the course lme. U.S Pat. No 4,528,804,
signal carried on a conductor which must be installed wluch lssuedto T- WUllams °n JuL 16' 198]5' dlscloses a
around the periphery of the plot of land to be mowed. sen?^g ">* for a row croP harvester guidance system
The mower includes a sensor for receiving the bound- wluch comprises a rotatably mounted crop engaging
ary signal as the mower approaches the boundary and ^ blased mt0 a croP engaging position by a torsion
control circuitry for steering the mower away from the 40 W^S- The spring tension is adjustable to vary the
boundary. U.S. Pat. No. 3,570,227, which issued to S. amount of force required to actuate the crop engaging
Bellinger on Mar. 16, 1971, discloses a self propelled arm- Variation of the force is desirable to permit the
lawn mower for cutting grass in a random and unat- sensing unit to operate reliably in a variety of crop and
tended manner. The mower is propelled by a battery fieid conditions. U.S. Pat. No. 4,603,753, which issued
and comprises a frame supported on a pair of front 45 to s- Yoshimura et al on Aug. 5, 1986, discloses an
castor wheels and a pair of rear drive wheels. The drive automated lawn mower which utilizes a pair of spaced
wheels are coupled to a continuously rotating drive photo sensors for detecting the swath boundary be
shaft by individual clutch brake mechanisms. When a tween cut and uncut grass. Control circuitry actuated
boundary wire installed around the perimeter of the by these photo sensors operate electro-magnetic valves
plot of land to be mowed is sensed by coils on the frame, 50 which operate hydraulic cylinders for steering the front
the drive wheel farthest away from the boundary is and rear wheels of the mower.
unclutched and braked to pivot or turn the mower. U.S. While the above mentioned devices are suited for Pat. No. 3,650,097, which issued to C. Nokes on Mar. their intended usage, none of these devices provide an 21, 1972, discloses a self propelled lawn mower for automated self propelled lawn mower which utilizes movement over a given land area in a preplanned route. 55 independent feedback controlled drive motors for indeThe mower has a frame and a steering mechanism with pendently driving the drive wheels of the lawn mower a tape extending between two reels with intermediate in accordance with information provided by touch elements contacted sequentially by the tape for provid- grass sensors and infrared obstacles sensors. Inasmuch ing a programmed tape mechanical control of the as the art is relatively crowded with respect to these course of the mower. U.S. Pat. No. 3,924,389, which 60 various types of automated lawn mowers, it can be issued to S. Kita on Dec. 9, 1975, discloses a lawn appreciated that there is a continuing need for and intermower which utilizes a sensor mounted on the front of est in improvements to such automated lawn mowers, the mower to detect the edge of the swath by sensing and in this respect, the present invention addresses this the difference in height between uncut and cut grass in need and interest.
the swath. An electrical signal is produced by the sen- 65 „m„.. „v TO„ ...
sors when it contacts the uncut grass and passes there- SUMMARY OF THE INVENTION
through a minute electrical current. The current is am- In view of the foregoing disadvantages inherent in
plified by a solid state amplifier circuit and fed to a pair the known types of automated lawn mowers now pres
