https://mowerproject.com/2020/09/22/the-robot-mower-in-action/https://mowerproject.com/wp-content/uploads/2020/09/img_4345.jpgIMG_4345The cross track error was pretty large. You can see my tape measure lying in the grass for scale.https://mowerproject.com/wp-content/uploads/2020/09/mission.pngmissionThe first autonomous mission for the robot mower. https://mowerproject.com/wp-content/uploads/2020/09/img_4338.jpgIMG_4338https://mowerproject.com/wp-content/uploads/2020/09/img_5677-e1600826581193.jpgIMG_5677Locknuts only work if the locking portion of the nut is engaged with the threads.https://mowerproject.com/wp-content/uploads/2020/09/img_6524-e1600826301562.jpgIMG_6524The turnbuckle holding the deck to the chassis needs to be larger.2022-07-26T03:39:11+00:00monthlyhttps://mowerproject.com/2021/05/31/vibration-issues-continued/https://mowerproject.com/wp-content/uploads/2021/05/mower-blade-assembly-bottom-1.pngmower blade assembly bottomThe bottom of the mower blade assembly. The two screws are the only thing that sets the position of the blade relative to the shaft adapter.https://mowerproject.com/wp-content/uploads/2021/05/mower-blade-assembly-bottom.pngmower blade assembly bottomThe mower blade assembly, looking at the bottom. The two screws are the only thing that sets the position of the blade relative to the shaft adapter.https://mowerproject.com/wp-content/uploads/2021/05/number-of-washers-to-balance.pngnumber of washers to balanceThe number of 1/4 washers you'd have to add to one of the mounting bolts to offset the imbalance inherent in the mower blade. https://mowerproject.com/wp-content/uploads/2021/05/length-to-remove.pnglength to removeHow much material that needs to be ground off the heavy end of the mower blade to achieve balance.https://mowerproject.com/wp-content/uploads/2021/05/mass-to-remove.pngmass to removeThe volume of material that needs to be removed from this specific mower blade assembly to align the center of mass with the rotation axis.https://mowerproject.com/wp-content/uploads/2021/05/where-is-the-actual-cg-2.pngWhere is the actual CGCalculations for determining the mower blade's eccentricity, or the distance away from the rotation axis the mower blade's center of mass lies.https://mowerproject.com/wp-content/uploads/2021/05/where-is-the-actual-cg-1.pngWhere is the actual CGCalculations for determining the mower blade's eccentricity, or the distance away from the rotation axis the mower blade's center of mass lies.https://mowerproject.com/wp-content/uploads/2021/05/unbalanced-force-calculation-2.pngUnbalanced Force CalculationCalculations for determining the mower blade's eccentricity, or the distance away from the rotation axis the mower blade's center of mass lies.https://mowerproject.com/wp-content/uploads/2021/05/where-is-the-actual-cg.pngWhere is the actual CGCalculations for determining the mower blade's eccentricity, or the distance away from the rotation axis the mower blade's center of mass lies.https://mowerproject.com/wp-content/uploads/2021/05/unbalanced-force-calculation-1.pngUnbalanced Force CalculationThe centrifugal force that 2.8g of unbalance results in.2021-07-22T20:55:23+00:00monthlyhttps://mowerproject.com/2021/05/19/vibration-issues/https://mowerproject.com/wp-content/uploads/2021/05/img_7637-e1621482035356.jpgIMG_7637Resonance, and the Magnification Factor, from Timoshenko's Vibration Problems in Engineering, page 42.https://mowerproject.com/wp-content/uploads/2021/05/img_7513.jpgIMG_7513The eyebolt on the turnbuckle supporting the mower deck. The vibration was so intense it peeled it open.https://mowerproject.com/wp-content/uploads/2021/05/unbalanced-force-calculation.pngUnbalanced Force Calculationhttps://mowerproject.com/wp-content/uploads/2021/05/img_7636.jpgIMG_76362021-05-20T12:27:41+00:00monthlyhttps://mowerproject.com/2021/04/05/wiring-improvements/https://mowerproject.com/wp-content/uploads/2021/04/img_7174-e1617678929572.jpgIMG_7174A proper ground plane for the GNSS antennas. The foil to the left was what was underneath the RTK GNSS receiver previously.https://mowerproject.com/wp-content/uploads/2021/04/img_7281-e1617676830232.jpgIMG_7281An RC controlled relay board.https://mowerproject.com/wp-content/uploads/2021/04/img_6921.jpgIMG_6921A fuse block for the mower deck motors. https://mowerproject.com/wp-content/uploads/2021/03/img_6696.jpgIMG_6696The way I had the power enclosure designed. The phrase "rat's nest" comes to mind.https://mowerproject.com/wp-content/uploads/2021/03/img_7179-e1616298855789.jpgIMG_7179The new power enclosure. No relays or terminal studs, just two motor controllers and a BEC.https://mowerproject.com/wp-content/uploads/2021/03/img_7184-e1616297550770.jpgIMG_7184The battery bay with batteries in place, looking forward.https://mowerproject.com/wp-content/uploads/2021/03/img_7247-e1617677620573.jpgIMG_7247Components relocate into the battery bay. From left to right, there's an RC controlled relay board, a solenoid, the voltage/current sensor, and a master fuse block.2021-04-06T06:16:12+00:00monthlyhttps://mowerproject.com/2021/01/07/inductive-kickback/https://mowerproject.com/wp-content/uploads/2021/01/inductive-kicback.pngInductive kicbackA typical graph of Inductive kickback voltage.2021-01-10T06:01:30+00:00monthlyhttps://mowerproject.com/2021/01/02/how-not-to-wire-up-a-robot/https://mowerproject.com/wp-content/uploads/2021/01/img_4358.jpgIMG_4358The robot mower battery bay. How many janky things can you spot?https://mowerproject.com/wp-content/uploads/2021/01/img_6553-e1609571695403.jpgIMG_6553One of the melted wires. The yellow blob on the end is a portion of a Posi-Lock.https://mowerproject.com/wp-content/uploads/2021/01/mission-planner-after-wire-failure-1.pngMission Planner After Wire Failurehttps://mowerproject.com/wp-content/uploads/2021/01/img_4350-1.jpgIMG_4350A typical shrub out in the field. Most were about 18in tall.2021-01-03T05:52:36+00:00monthlyhttps://mowerproject.com/2020/10/18/robot-mower-performance/https://mowerproject.com/wp-content/uploads/2020/10/mag-y-versus-current.pngmag y versus currentThe magnetometers reported Y magnitude versus the total current used by the robot.https://mowerproject.com/wp-content/uploads/2020/10/rtk-status.pngrtk statusThe fix status for the ZED-F9P GNSS module. 6 is RTK fixed.https://mowerproject.com/wp-content/uploads/2020/10/tip-calc.pngtip calcThe calculation for blade tip speed with a motor rotation speed of 4800RPM and a blade length of 1ft.https://mowerproject.com/wp-content/uploads/2020/10/fft-1.pngfftThe amplitude of vibration in the X, Y and Z directions on the robot mower across the frequency spectrum.https://mowerproject.com/wp-content/uploads/2020/10/fft.pngfftThe amplitude of vibration in the X, Y and Z directions on the robot mower across the frequency spectrum.https://mowerproject.com/wp-content/uploads/2020/10/performance-2.pngperformancePerformance characteristics for the robot lawn mower in the field.https://mowerproject.com/wp-content/uploads/2020/10/power-calc.pngpower calcA simple way to calculate the power consumption for the robot mower.https://mowerproject.com/wp-content/uploads/2020/10/energy-tot.pngenergy totA running total of the energy used by the robot over time. Find the slope of that line and you've got the average power consumption over that time period.https://mowerproject.com/wp-content/uploads/2020/10/voltage-versus-current.pngvoltage versus currentBattery voltage level before and after the deck motors were turned on.https://mowerproject.com/wp-content/uploads/2020/10/steer-versus-current.pngsteer versus currentCurrent consumption versus steering commands. Each spike on the green line is the robot mower making a pivot turn at the end of a pass.2021-01-04T10:24:30+00:00monthlyhttps://mowerproject.com/2020/07/25/mower-blades-more-complex-than-youd-think/https://mowerproject.com/wp-content/uploads/2020/07/ego-lawn-mower-blades-ab2000-64_1000-e1595734352162.jpgego-lawn-mower-blades-ab2000-64_1000A typical mower blade.https://mowerproject.com/wp-content/uploads/2020/07/image-91-802-blount-1200wx1200h.jpgimage-91-802-Blount-1200Wx1200HA typical https://mowerproject.com/wp-content/uploads/2020/07/the-best-option.pngthe best optionThe 1in OD shaft coupling welded to a plate. The cotter pin keeps the coupling on the shaft.https://mowerproject.com/wp-content/uploads/2020/07/img_6250-e1595733525719.jpgIMG_6250A 0.5in ID X 1in OD solid shaft coupling with four set screws.https://mowerproject.com/wp-content/uploads/2020/07/combined-1-e1595736176516.pngcombinedMy first idea for a mower adapter: a machined piece of round stock.2020-09-07T02:31:06+00:00monthlyhttps://mowerproject.com/2020/07/06/an-even-better-rtk-fix/https://mowerproject.com/wp-content/uploads/2020/07/with-foil-ground-plane-nsats-status.pngWith foil ground plane nsats + statusThe RTK GNSS receiver performance with a foil ground plane.https://mowerproject.com/wp-content/uploads/2020/07/no-foil-ground-plane-nsats-status.pngno foil ground plane nsats + statusThe RTK GNSS performance without a foil ground plane. Left vetical axis is fix status where 6 = RTK fixed, and right vertical axis is the number of satellites seen by the receiver.https://mowerproject.com/wp-content/uploads/2020/07/img_6167-e1594009947451.jpgIMG_6167An aluminum foil ground plane underneath the RTK GNSS antenna.2020-07-23T04:01:25+00:00monthlyhttps://mowerproject.com/2020/06/05/the-right-problem/2020-08-09T02:23:58+00:00monthlyhttps://mowerproject.com/2020/05/30/the-productivity-problem-a-really-long-editorial/https://mowerproject.com/wp-content/uploads/2020/04/greenpal_contractor.jpgGreenPal_ContractorJoe's Mowing Company.2020-07-22T00:48:45+00:00monthlyhttps://mowerproject.com/2020/05/15/a-better-rtk-fix/https://mowerproject.com/wp-content/uploads/2020/05/no-rtk.pngno rtkThe position solution with only a 3D Fix from the ZED-F9P. The red track is still solid.https://mowerproject.com/wp-content/uploads/2020/05/multiple-loops.pngmultiple loopsSeveral loops of the square mission. Even with some bad position data from the ZED-F9P module (green track) the position estimate (red track) is still rock solid.https://mowerproject.com/wp-content/uploads/2020/05/without-rtk-fix-good-pos.pngwithout rtk fix good posAn excellent position estimate even with spotty RTK fixes.https://mowerproject.com/wp-content/uploads/2020/05/good-rtk.pnggood rtkA good position estimate 2020-07-06T06:37:30+00:00monthlyhttps://mowerproject.com/2020/05/12/a-day-in-the-parking-lot/https://mowerproject.com/wp-content/uploads/2020/05/bad-gps.pngbad gpsAn example of how the position solution from the EKF jumps when RTK fix is lost.https://mowerproject.com/wp-content/uploads/2020/05/perfect-circle-mission.pngperfect circle missionA circle mission in the parking lot with RTK GPS.https://mowerproject.com/wp-content/uploads/2020/05/img_1534.jpgIMG_1534The parking lot. Wide open skies and flat pavement, a perfect laboratory for implementing the RTK GPS modules.https://mowerproject.com/wp-content/uploads/2020/05/img_1532.jpgIMG_1532Transporting the robot lawn mower. With the lead acid batteries installed, it weighs close to 300lb.2020-05-13T03:42:59+00:00monthlyhttps://mowerproject.com/2020/05/03/rotary-encoder-troubleshooting/https://mowerproject.com/wp-content/uploads/2020/05/img_5572-e1588539786491.jpgIMG_5572The armature of the wheel chair motor.https://mowerproject.com/wp-content/uploads/2020/05/img_5569-e1588535800440.jpgIMG_5569Encoder signal sires inside the cap of the motor housing. No wonder I kept frying encoders.2020-05-03T21:11:34+00:00monthlyhttps://mowerproject.com/2020/04/22/zed-f9p-notes/https://mowerproject.com/wp-content/uploads/2020/04/loadsave-receiver-config.pngloadsave receiver configThe Receiver Configuration window. Save a back up of your existing configuration, just in case!https://mowerproject.com/wp-content/uploads/2020/04/firmware-update.pngfirmware updateThe settings I used at the advice of the ArduSimple website.2020-04-27T02:11:13+00:00monthlyhttps://mowerproject.com/2020/04/16/mower-deck-installation/https://mowerproject.com/wp-content/uploads/2020/04/img_5452-e1587012291450.jpgIMG_5452The turnbuckles used to attach the rear of the mower deck to the robot.https://mowerproject.com/wp-content/uploads/2020/04/img_5450-e1587011878585.jpgIMG_5450The bushing that came with the cable gland I used to route the deck motor cables. Not even close to the right size.https://mowerproject.com/wp-content/uploads/2020/04/img_5459-e1587011388108.jpgIMG_5459The prototype lawn mower with the mower deck installed.2020-04-17T02:36:13+00:00monthlyhttps://mowerproject.com/2020/04/13/the-prototype-robot-lawn-mower/https://mowerproject.com/wp-content/uploads/2020/04/bad-encoder.pngbad encoderThe WENC.Dist0 and WENC.Dist1 values after swapping the encoders.https://mowerproject.com/wp-content/uploads/2020/04/bad-left-encoder.pngbad left encoderThe bad right encoder. Having watched the robot move around my backyard, I know this can't be correct.https://mowerproject.com/wp-content/uploads/2020/04/kind-of-bad-encoder.pngkind of bad encoderWheel encoder total distance traveled as measured from the right and left wheel encoders. Note that WENC.Dist1 is 0.https://mowerproject.com/wp-content/uploads/2020/04/img_5416.jpgIMG_5416A scenario I hadn't considered when I designed the robot mower.https://mowerproject.com/wp-content/uploads/2020/04/img_5418.jpgIMG_5418The prototype robot lawn mower, without the mower deck.2020-09-07T02:27:50+00:00monthlyhttps://mowerproject.com/2020/03/26/assembly/https://mowerproject.com/wp-content/uploads/2020/03/img_5301-e1585200473137.jpgIMG_5301The chassis of the robot mower with wheels and motors installed.2020-07-14T19:12:22+00:00monthlyhttps://mowerproject.com/2020/01/06/finishing-touches/https://mowerproject.com/wp-content/uploads/2020/01/mower-deck.jpgmower deckThe mower deck weldment just before Christmas, 2019.https://mowerproject.com/wp-content/uploads/2020/01/gnss-enclosure.pnggnss enclosureA custom GNSS antenna enclosure. The larger GNSS antenna is for the Ardusimple RTK GNSS module. The smaller one is a UBlox M8N.https://mowerproject.com/wp-content/uploads/2020/01/img_5142-e1578370678282.jpgIMG_5142The turnbuckle that will replace the chain used to attach the mower deck to the chassis.2022-04-19T19:47:23+00:00monthlyhttps://mowerproject.com/2019/12/22/the-time-flies/https://mowerproject.com/wp-content/uploads/2019/12/img_5088-e1576907751216.jpgIMG_5088A newspaper page I found inside my box of five 5/8-11 X 5.5in long socket head cap screws.2020-01-06T15:55:20+00:00monthlyhttps://mowerproject.com/2019/12/20/sub-assembly/https://mowerproject.com/wp-content/uploads/2019/12/img_5009.jpgIMG_5009The completed motor assembly with the Harbor Freight tire.https://mowerproject.com/wp-content/uploads/2019/12/img_4701.jpgIMG_4701How I initially had the wheel encoders installed. You can see a little rubber grommet in a hole I drilled in the motor dust cover.https://mowerproject.com/wp-content/uploads/2019/12/img_5011.jpgIMG_5011https://mowerproject.com/wp-content/uploads/2019/12/img_5010.jpgIMG_5010https://mowerproject.com/wp-content/uploads/2019/12/img_5005-e1576905288863.jpgIMG_5005How I should have routed the encoder data cables from the start.https://mowerproject.com/wp-content/uploads/2019/12/img_5002-e1576905200814.jpgIMG_5002The inside of the aluminum back piece.https://mowerproject.com/wp-content/uploads/2019/12/img_5085.jpgIMG_5085The front caster assembly. A little bigger than I expected!https://mowerproject.com/wp-content/uploads/2019/12/img_5025.jpgIMG_5025The reassembled motor with the encoder mounted on the back. You can see those pesky2019-12-24T02:40:15+00:00monthlyhttps://mowerproject.com/2019/12/09/innovators-in-the-autonomous-lawn-mower-realm/https://mowerproject.com/wp-content/uploads/2019/12/autonomous_mower_fmt-1.pngautonomous_mower_fmtMean Green Mower's autonomous mower. Great minds think alike?https://mowerproject.com/wp-content/uploads/2019/12/autonomous_mower_fmt.pngautonomous_mower_fmtMean Green Mower's autonomous mower. Great minds think alike!2020-07-24T21:02:31+00:00monthlyhttps://mowerproject.com/2019/11/20/weldments/https://mowerproject.com/wp-content/uploads/2019/11/untitled.pngUntitledThe miter angle is 55°. Or is it?https://mowerproject.com/wp-content/uploads/2019/11/img_e4912-e1574308405935.jpgIMG_E4912The main chassis weldment.https://mowerproject.com/wp-content/uploads/2019/11/img_4913-e1574308489653.jpgIMG_4913The main chassis weldment side view.https://mowerproject.com/wp-content/uploads/2019/11/img_4912.jpgIMG_4912https://mowerproject.com/wp-content/uploads/2019/11/img_4910-e1574304834463.jpgIMG_4910The tubes for the front caster wheels.https://mowerproject.com/wp-content/uploads/2019/11/img_4875.jpgIMG_48752019-11-21T04:03:56+00:00monthlyhttps://mowerproject.com/2019/11/16/lawn-mower-safety-regulations-a-brief-history/2019-11-17T04:19:07+00:00monthlyhttps://mowerproject.com/2019/10/28/a-new-addition-to-the-mr-mower-family/https://mowerproject.com/wp-content/uploads/2019/10/68993112_10157592162359312_6153332179632914432_n.jpg68993112_10157592162359312_6153332179632914432_nThe Mr. Mower family is growing!2019-11-13T03:11:10+00:00monthlyhttps://mowerproject.com/2019/10/07/the-sky-is-the-limit/https://mowerproject.com/wp-content/uploads/2019/10/manned-versus-unmanned.jpgManned Versus UnmannedAn MQ-9 Reaper military drone comparted to the T-6 Texan II. Both aircraft are similar in size.https://mowerproject.com/wp-content/uploads/2019/10/compare.pngcompareA comparison of size and weight between the prototype robotic lawn mower and the 36in Swisher ZTR mower.2019-11-13T03:14:06+00:00monthlyhttps://mowerproject.com/2019/08/31/procurement/https://mowerproject.com/wp-content/uploads/2019/08/extra-flange-bearings-e1567308123837.pngextra flange bearingsThe mounting method for the casters. The extra flange bearings get used here.https://mowerproject.com/wp-content/uploads/2019/08/img_4667-e1567307643653.jpgIMG_4667The "caster wheels" are the two at top. The "drive wheels" are the two at bottom.https://mowerproject.com/wp-content/uploads/2019/08/img_4666.jpgIMG_4666https://mowerproject.com/wp-content/uploads/2019/08/img_4665-e1567301264785.jpgIMG_4665The wheels disassembled. Deflating them helps make disassembly easier.https://mowerproject.com/wp-content/uploads/2019/08/img_4664-e1567307105758.jpgIMG_4664I had to drill a hole in the hub piece with the bearings in it.https://mowerproject.com/wp-content/uploads/2019/08/img_4663.jpgIMG_4663https://mowerproject.com/wp-content/uploads/2019/08/img_4687-e1567297490769.jpgIMG_4687The hardware haul from The Yard. Not bad for an hour of digging. Total cost here was $52.https://mowerproject.com/wp-content/uploads/2019/08/img_4688-e1567297247179.jpgIMG_4688Hubs for my drive wheels. Finding a hub with a 17mm ID shaft with a 2.75in bolt circle was not easy.2022-04-24T07:04:29+00:00monthlyhttps://mowerproject.com/2019/08/02/making-new-things-is-hard/https://mowerproject.com/wp-content/uploads/2019/08/tooling.pngtoolingThe tools I'll need to make all the parts for the prototype robot lawn mower.2019-08-03T04:20:23+00:00monthlyhttps://mowerproject.com/2019/07/25/combined-battery-bays/https://mowerproject.com/wp-content/uploads/2019/07/bottom-compare.pngbottom compareThe bottom view of version 5 and version 6.https://mowerproject.com/wp-content/uploads/2019/07/four-view.pngfour viewVarious viewshttps://mowerproject.com/wp-content/uploads/2019/07/version-5-and-6-compare-2.pngversion 5 and 6 comparehttps://mowerproject.com/wp-content/uploads/2019/07/version-5-and-6-compare-1.pngversion 5 and 6 compareVersion 5 of the robot lawn mower (left) compared to version 6 (right).https://mowerproject.com/wp-content/uploads/2019/07/version-5-and-6-compare.pngversion 5 and 6 compareVersion 5 compared to version 6 of the robot lawn mower.https://mowerproject.com/wp-content/uploads/2019/07/version-6.pngVERSION 62019-07-25T05:56:27+00:00monthlyhttps://mowerproject.com/2019/07/10/where-does-all-that-power-go/https://mowerproject.com/wp-content/uploads/2019/07/gas-versus-electric-comparison.pngGas Versus Electric Comparison2021-02-01T05:17:14+00:00monthlyhttps://mowerproject.com/2019/07/02/battery-selection-revisited/https://mowerproject.com/wp-content/uploads/2019/07/sp12-35-discharge-characteristics.pngSP12-35 Discharge CharacteristicsRun times and terminal voltages for our 12V, 35Ah SLA battery at various discharge rates.https://mowerproject.com/wp-content/uploads/2019/07/untitled-3.pngUntitledThe C-rate if you were to discharge a 10Ah battery at 5A.https://mowerproject.com/wp-content/uploads/2019/06/battery-e1561953952466.jpgbatteryA typical lead acid battery. It's 12V, 80Ah. Or is it?2019-07-05T13:55:41+00:00monthlyhttps://mowerproject.com/2019/06/29/is-a-compass-even-necessary/https://mowerproject.com/wp-content/uploads/2019/06/bad-compass-health.pngbad compass healthMy favorite Mission Planner error message: Bad Compass Health.2019-06-30T00:13:22+00:00monthlyhttps://mowerproject.com/2019/06/21/a-poor-mans-rtk-base-station/https://mowerproject.com/wp-content/uploads/2019/06/the-tripod-mount-method-e1561156793706.pngThe tripod mount methodThe coupling nut used to interface the enclosure with the tripod. This makes it easy to remove and pack it in my car.https://mowerproject.com/wp-content/uploads/2019/06/bom.pngbomBill of material for the poor man's RTK GPS base station.https://mowerproject.com/wp-content/uploads/2019/06/enclosure-closeup-1.pngenclosure closeuphttps://mowerproject.com/wp-content/uploads/2019/06/enclosure-closeup-e1561155777795.pngenclosure closeupA poor man's Reach RS2.https://mowerproject.com/wp-content/uploads/2019/06/tripod-stud.pngtripod studThe tripod we'll be using. The 5/8-11 UNC stud is stout, but a little inconvenient.https://mowerproject.com/wp-content/uploads/2019/06/rstp-a10001-06-21-19-1.pngRSTP-A10001 (06-21-19)My version of the Emlid Reach RS2. No Wi-Fi, but it only costs $200 plus the cost of the Ardusimple modules.https://mowerproject.com/wp-content/uploads/2019/06/rstp-a10001-06-21-19.pngRSTP-A10001 (06-21-19)My version of the Emlid RS2. No Wi-Fi capability, but it only costs $200 plus the price of the Ardusimple modules.2019-07-29T07:40:09+00:00monthlyhttps://mowerproject.com/2019/06/10/field-testing-and-rtk-gps-stuff/https://mowerproject.com/wp-content/uploads/2019/06/rtk-status-1-e1560144390400.pngrtk statusThe fix status across time. 6 is an RTK Fix, 5 is RTK Float.https://mowerproject.com/wp-content/uploads/2019/06/gps-status-1-e1560144413643.pnggps statusHow much time was spent in each fix status.https://mowerproject.com/wp-content/uploads/2019/06/rtk-fixed-graph.pngrtk fixed graphThe latitude reported by the U-Blox Neo-M8N, U-Blox Zed-F9P, and the EKF position estimate in blue, green, and red, respectively.https://mowerproject.com/wp-content/uploads/2019/06/img_5372.jpgIMG_5372The view from the ground. The RTK GPS base station can be seen on the mailbox if you look closely.https://mowerproject.com/wp-content/uploads/2019/06/rtk-map.pngrtk mapThe circular mission in my front lawn. The satellite imagery is from winter time. GPS in blue is the U-Blox Neo-M8N, GPS2 in green is the U-Blox Zed-F9P, and POS in red is the calculated position by the EKF.https://mowerproject.com/wp-content/uploads/2019/06/ster-rate.pngster rateDesired steering rate versus actual steering rate. Because the wheelchair robot is a skid steer vehicle, you can get some pretty ridiculous turn rates. In manual mode it's something like 250degrees/s.https://mowerproject.com/wp-content/uploads/2019/06/throttle.pngthrottleDesired speed versus achieved actual speed before tuning. I have the autopilot requesting 2m/s speed, but the rover is only capable of achieving 1.1m/s.https://mowerproject.com/wp-content/uploads/2019/06/img_5373-e1560138643815.jpgIMG_5373The base station, located on top of my community mailbox. Neighbors give me funny looks when they go to get their mail.2019-06-10T05:50:52+00:00monthlyhttps://mowerproject.com/2019/06/02/its-the-wires-dummy/2019-06-02T20:00:46+00:00monthlyhttps://mowerproject.com/2019/05/18/encoder-math/https://mowerproject.com/wp-content/uploads/2019/05/travel-per-count-1.pngtravel per countThe distance the tire travels after one encoder count.https://mowerproject.com/wp-content/uploads/2019/05/travel-per-count.pngtravel per countThe distance the tire will advance after one encoder count.https://mowerproject.com/wp-content/uploads/2019/05/pulses-at-150rpm.pngpulses at 150rpmThe number of pulses in one second if the tire on the gear motor rotates at 150RPM.https://mowerproject.com/wp-content/uploads/2019/05/max-tire-speed.pngmax tire speedThe maximum rotation speed of the tire on the gear motor for a given maximum encoder rotation speed.https://mowerproject.com/wp-content/uploads/2019/05/rpm1-and-rpm2.pngRPM1 and RPM2Reported RPM values for the left and right motors.2019-05-18T21:50:11+00:00monthlyhttps://mowerproject.com/2019/05/01/correction-the-magic-number-is-exactly-32/https://mowerproject.com/wp-content/uploads/2019/05/untitled.pngUntitledThe composite gear ratio for the wheelchair gearbox.https://mowerproject.com/wp-content/uploads/2019/05/gear-model-e1556688834746.pnggear modelA simple model of the gears in the gear box. The left gear has the output shaft with the tire on it, and the lower right cylinder represents the worm gear attached to the motor.https://mowerproject.com/wp-content/uploads/2019/05/img_4383.jpgIMG_4383https://mowerproject.com/wp-content/uploads/2019/05/img_4382.jpgIMG_4382https://mowerproject.com/wp-content/uploads/2019/05/img_4381-e1556688188784.jpgIMG_4381The wheelchair motor gear box. Lots of grease!2019-05-03T01:23:15+00:00monthlyhttps://mowerproject.com/2019/04/24/the-magic-number-is-31-8/https://mowerproject.com/wp-content/uploads/2019/04/img_4374-e1556081983374.jpgIMG_4374The setup for measuring the wheelchair gearmotor gear ratio. The encoder and Arduino are measuring input shaft revolutions and I'm measuring tire revolutions with my eyes.https://mowerproject.com/wp-content/uploads/2019/04/img_4373-e1556080453968.jpgIMG_4373The rotary encoder mounted to the wheelchair motor.https://mowerproject.com/wp-content/uploads/2019/04/img_4372.jpgIMG_43722019-04-25T04:04:04+00:00monthlyhttps://mowerproject.com/2019/04/16/spring-is-here/https://mowerproject.com/wp-content/uploads/2019/04/encoder-on-motor-e1555389964125.pngencoder on motorThe wheel encoders mounted where the brake used to be on the motor. Fits like a mitten!https://mowerproject.com/wp-content/uploads/2019/04/img_4337-e1555388095453.jpgIMG_4337The backyard on this fine spring morning. Winter is finally over!2022-02-21T12:17:28+00:00monthlyhttps://mowerproject.com/2019/03/19/the-culprit/https://mowerproject.com/wp-content/uploads/2019/03/img_4307-e1552968067683.jpgIMG_4307The dual relay module. The module features two 30VDC, 10A relays soldered to the board.https://mowerproject.com/wp-content/uploads/2019/03/img_4308-e1552967846521.jpgIMG_4308The bottom of damaged relay board.2019-03-19T05:15:54+00:00monthlyhttps://mowerproject.com/2019/03/04/weather/https://mowerproject.com/wp-content/uploads/2019/03/robot-mower-03-03-19-e1551678648665.pngRobot Mower (03-03-19)The robot mower design as of this evening.2019-03-04T06:22:14+00:00monthlyhttps://mowerproject.com/2019/02/03/more-backyard-testing/https://mowerproject.com/wp-content/uploads/2019/02/img_4267.pngIMG_4267The black tick marks is the position of the front caster as it runs a loop in my driveway.https://mowerproject.com/wp-content/uploads/2019/02/img_4241-e1549248617280.jpgIMG_4241The robot wheelchair with the RTK GNSS antenna mounted to the top enclosure. The second longer antenna is for RTCM corrections from the base station.https://mowerproject.com/wp-content/uploads/2019/02/image-1-e1549247523966.jpgImage-1The base station is on the grill. The thought was the metal shell would make a good ground plane to mitigate multipath.2019-04-04T02:22:49+00:00monthlyhttps://mowerproject.com/2019/02/05/setbacks/https://mowerproject.com/wp-content/uploads/2019/02/img_4264-e1549252942276.jpgIMG_4264The bench setup for checking the Sabertooth. The battery and motor come from an old cordless weed eater.2019-02-04T04:28:57+00:00monthlyhttps://mowerproject.com/2019/01/10/small-design-changes/https://mowerproject.com/wp-content/uploads/2019/01/xt60.pngxt60Some simple XT60 connectors for the motors. They're rated for 60A and should be appropriate for this application.https://mowerproject.com/wp-content/uploads/2019/01/mower-1-6-19.pngmower 1-6-19The robot mower design as of this weekend. Some wiring is completed.2019-01-07T05:45:20+00:00monthlyhttps://mowerproject.com/2019/01/06/u-blox-zed-f9p/https://mowerproject.com/wp-content/uploads/2019/01/img_4193.jpgimg_4193My backyard. The deck where the test was conducted is on the right.https://mowerproject.com/wp-content/uploads/2019/01/img_4208.pngimg_4208https://mowerproject.com/wp-content/uploads/2019/01/img_4207.pngimg_4207https://mowerproject.com/wp-content/uploads/2019/01/img_4206.pngimg_4206https://mowerproject.com/wp-content/uploads/2019/01/img_4198.jpgimg_4198https://mowerproject.com/wp-content/uploads/2019/01/img_4197.jpgimg_4197The test setup. The receiver on the left is the base, the on the right near the laptop is the rover. Yes, that is my neighbor's two story houses in the background.https://mowerproject.com/wp-content/uploads/2019/01/img_4196.jpgimg_41962019-01-07T05:07:25+00:00monthlyhttps://mowerproject.com/2019/01/06/mower-positioning/https://mowerproject.com/wp-content/uploads/2019/01/5939749916dcd.image_.jpg5939749916dcd.imageA typical robot lawn mower on the market today. It's basically a Roomba, but for your lawn. Have fun tearing up your lawn to bury cable!2019-01-07T03:10:45+00:00monthlyhttps://mowerproject.com/2018/12/28/lithium-batteries/https://mowerproject.com/wp-content/uploads/2018/12/Untitled.pngUntitledWhat the performance of a hypothetical lithium ion battery could look like if we were to use one.https://mowerproject.com/wp-content/uploads/2018/12/Lithiums-e1546025902764.pngLithiumsHow the lithium batteries would fit in the battery bays. Very compact. Very expensive.2018-12-28T20:05:38+00:00monthlyhttps://mowerproject.com/2018/12/28/power-consumption-revisited/https://mowerproject.com/wp-content/uploads/2018/12/Lithium-Lead-Acid-Comparison.pngLithium Lead Acid ComparisonA brief cost and performance comparison of a composite lithium ion battery versus our current 12V, 35Ah SLA battery.2018-12-28T08:41:01+00:00monthlyhttps://mowerproject.com/2018/12/20/power-consumption/2018-12-28T08:34:12+00:00monthlyhttps://mowerproject.com/2018/12/12/progress/https://mowerproject.com/wp-content/uploads/2018/12/combine.pngcombineThe robot lawn mower design.https://mowerproject.com/wp-content/uploads/2018/12/progress.pngprogressThe current progress on the lawn mower design.2018-12-13T00:24:15+00:00monthlyhttps://mowerproject.com/2018/11/23/project-goals/2021-04-01T18:05:26+00:00monthlyhttps://mowerproject.com/2018/11/14/adjusting-the-mower-deck-height/https://mowerproject.com/wp-content/uploads/2018/11/deck-height-adjust-detail-e1542176365677.pngdeck height adjust detailA close up of the adjustment lever.https://mowerproject.com/wp-content/uploads/2018/11/deck-height-adjustment.pngdeck height adjustmentA simple height adjustment mechanism for the mower deck.2018-11-14T06:24:55+00:00monthlyhttps://mowerproject.com/2018/11/04/concept-5-refined/https://mowerproject.com/wp-content/uploads/2018/11/xrlm-a10001-versus-prlm-a50001-isometric-e1541396863111.pngXRLM-A10001 Versus PRLM-A50001 IsometricBigger than I wanted it to be, but still pretty small overall.https://mowerproject.com/wp-content/uploads/2018/11/prlm-a50001-11-04-18-e1541395434665.pngPRLM-A50001 (11-04-18)The autonomous lawn mower as of this evening.https://mowerproject.com/wp-content/uploads/2018/11/xrlm-a10001-versus-prlm-a50001-e1541395072265.pngXRLM-A10001 Versus PRLM-A50001The electric wheel chair robot versus the autonomous lawn mower. 2018-11-08T06:32:10+00:00monthlyhttps://mowerproject.com/2018/11/01/concept-5/https://mowerproject.com/wp-content/uploads/2018/11/prlm-a50001-e1541049832117.pngPRLM-A50001An idea I've been playing with lately.2018-11-01T05:25:50+00:00monthlyhttps://mowerproject.com/2018/10/22/e30-400-motor-evaluation/https://mowerproject.com/wp-content/uploads/2018/10/e30-400_chart.pngE30-400_ChartPerformance curves for the AmpFlow E30-400 DC motor.2020-05-14T02:51:01+00:00monthlyhttps://mowerproject.com/2018/10/21/mower-design-how-many-blades/https://mowerproject.com/wp-content/uploads/2018/10/three-blade-e1540182240259.pngthree bladeThe three blade mower deck design.https://mowerproject.com/wp-content/uploads/2018/10/blade-rotation-speed.pngblade rotation speedThe relationship between blade tip speed and blade rotation speed.https://mowerproject.com/wp-content/uploads/2018/10/craftsman-40v-mower-underbody-blades-e1540180152251.jpgCraftsman-40v-mower-underbody-bladesTypical view of the underside of a two blade mowerd deck.https://mowerproject.com/wp-content/uploads/2018/10/offset-2-blade1-e1540160810320.pngoffset 2 bladeThe two blade angled mower deck.https://mowerproject.com/wp-content/uploads/2018/10/offset-2-blade-e1540160651678.pngoffset 2 bladefhttps://mowerproject.com/wp-content/uploads/2018/10/2blade-e1540159276260.png2bladeThe twohttps://mowerproject.com/wp-content/uploads/2018/10/dfsa-e1540158916569.pngdfsaDimensions of the top of the single blade mower deck. Length is 37.5in, width will 31in for a 30in blade.2018-10-22T05:12:27+00:00monthlyhttps://mowerproject.com/2018/10/13/vehicle-kinematics/https://mowerproject.com/wp-content/uploads/2018/10/specs1.pngspecsSome high level measures for the three configurations. I didn't design them in order of number of blades, that's why the designations don't match.https://mowerproject.com/wp-content/uploads/2018/10/comparison-10-13-18-e1539414673522.pngComparison (10-13-18)Some different mower designs.2018-10-13T07:11:22+00:00monthlyhttps://mowerproject.com/2018/10/01/more-mower-musings/https://mowerproject.com/wp-content/uploads/2018/10/ryobi-rear-engine-riding-mowers-ry48110-64_1000.jpgryobi-rear-engine-riding-mowers-ry48110-64_1000The Ryobi RY48110 electric riding mower. I wonder what's inside?2018-10-06T06:25:29+00:00monthlyhttps://mowerproject.com/2018/09/16/mower-musings/https://mowerproject.com/wp-content/uploads/2018/09/velocity1.pngvelocityThe maximum angular velocity of a 21in mower blade for compliance with ANSI B71.1-1990. Don't forget the calculation between radians and revolutions.https://mowerproject.com/wp-content/uploads/2018/09/img_3958-e1537157349205.jpgIMG_3958The motor from Craigslist. The label says "24VDC 500W 4300RPM".https://mowerproject.com/wp-content/uploads/2018/09/stall-torque-and-max-power.pngstall torque and max powerThe calculation for the stall torque (top) and maximum power (bottom).https://mowerproject.com/wp-content/uploads/2018/09/motor-specs.pngmotor specsThe best information I could find for the motor I salvaged.https://mowerproject.com/wp-content/uploads/2018/09/min-power.pngMin powerThe minimum power our motor needs to supply to keep a 21in blade spinning at 3450RPM.https://mowerproject.com/wp-content/uploads/2018/09/e450-engine-series-gross-torque.pnge450 engine series gross torqueThe gross torque versus RPM curve for a Briggs and Stratton 450e series engine.https://mowerproject.com/wp-content/uploads/2018/09/velocity.pngvelocityThe maximum angular velocity of a 21in mower blade for compliance with ANSI B71.1-1990. Don't forget the calculation between radians and revolutions, which is not shown here.2018-10-06T06:25:04+00:00monthlyhttps://mowerproject.com/2018/10/06/selecting-a-motor/https://mowerproject.com/wp-content/uploads/2018/10/48v1500w.jpg48v1500wThe BLDC-108. https://mowerproject.com/wp-content/uploads/2018/10/bldc-108-speed-torque-power2.pngBLDC-108 speed torque powerThe speed and power versus torque curves for the BLDC-108 motor. Excel only lets you plot two separate y-axes. Very frustrating. This is 2018!2018-10-06T06:23:57+00:00monthlyhttps://mowerproject.com/2018/09/14/the-emergency-stop-switch/https://mowerproject.com/wp-content/uploads/2018/09/img_3956-e1537151880541.jpgIMG_3956The big red button installed on the rover. Be sure to include large, clear signage stating that this is how you shut it off!https://mowerproject.com/wp-content/uploads/2018/09/safety-system2.pngSafety SystemThe wiring diagram for the emergency stop system.https://mowerproject.com/wp-content/uploads/2018/09/img_3946-e1536962670526.jpgIMG_3946The big red button installed on the rover.https://mowerproject.com/wp-content/uploads/2018/09/relay-e1536960419247.pngRelayThe power enclosure with the relay module mounted nicely in the lower right.2018-09-17T02:39:13+00:00monthlyhttps://mowerproject.com/2018/09/09/safety-first/https://mowerproject.com/wp-content/uploads/2018/08/emergency-stop-switch-1.jpgemergency-stop-switch-1https://mowerproject.com/wp-content/uploads/2018/08/0cqka7d.jpg0CQKa7d2018-09-10T03:30:25+00:00monthlyhttps://mowerproject.com/2018/06/30/more-planning/https://mowerproject.com/wp-content/uploads/2018/06/battery-and-motor-connectors.pngbattery and motor connectorshttps://mowerproject.com/wp-content/uploads/2018/06/posi-lock.jpgposi-lockA 26 gage Posi-Lock connector.https://mowerproject.com/wp-content/uploads/2018/06/adjustable-control-box-mount.pngadjustable control box mounthttps://mowerproject.com/wp-content/uploads/2018/06/control-enclosure-mount-e1530383599879.pngcontrol enclosure mountThe control enclosure mount.https://mowerproject.com/wp-content/uploads/2018/06/power-enclosure-mounting.pngpower enclosure mountinghttps://mowerproject.com/wp-content/uploads/2018/06/adapter-plate-detail.pngadapter plate detailhttps://mowerproject.com/wp-content/uploads/2018/06/adapter-plate1-e1530376478206.pngadapter plateThe male DB15 breakout board. The jack screws clamp the breakout board to the adapter plate, and the adapter plate screws into the enclosure wall.https://mowerproject.com/wp-content/uploads/2018/06/control-enclosure-e1530385365616.pngcontrol enclosureThe control enclosure containing the Pixhawk, telemetry radio, RC receiver, PPM encoder, and DB15 breakout board.https://mowerproject.com/wp-content/uploads/2018/06/power-enclosure1-e1530385401974.pngpower enclosurehttps://mowerproject.com/wp-content/uploads/2018/06/power-enclosure.pngpower enclosure2018-08-29T04:17:15+00:00monthlyhttps://mowerproject.com/2018/08/28/field-testing/https://mowerproject.com/wp-content/uploads/2018/08/img_3862_moment-e1535500341756.jpgIMG_3862_MomentThe rover V2 in the parking lot.https://mowerproject.com/wp-content/uploads/2018/08/img_3854-e1535341134624.jpgIMG_3854The rover V2 running to waypoints autonomously.2018-08-28T23:56:03+00:00monthlyhttps://mowerproject.com/2018/08/22/getting-the-wheels-to-turn-the-right-way/https://mowerproject.com/wp-content/uploads/2018/08/ppm.pngppmhttps://mowerproject.com/wp-content/uploads/2018/08/sabertooth-dip-switch-settings.jpgSabertooth DIP Switch SettingsThe DIP switch settings I used on the Sabertooth 2X60. Switches 2 and 3 are on, the rest are off.2018-08-29T02:10:23+00:00monthlyhttps://mowerproject.com/2018/08/16/the-rover-v2/https://mowerproject.com/wp-content/uploads/2018/08/img_3855.jpgIMG_3855The Rover V2. 2018-08-17T03:41:20+00:00monthlyhttps://mowerproject.com/2018/08/12/the-control-enclosure/https://mowerproject.com/wp-content/uploads/2018/08/img_3874-e1534116081748.jpgIMG_3874The control enclosure.https://mowerproject.com/wp-content/uploads/2018/08/img_3872-e1534115710841.jpgFinished Control EnclosureThe two GPS receivers mounted on top. The one on the right is a U-Blox NEO M8N, the left is a NEO 6M.2018-08-17T03:40:34+00:00monthlyhttps://mowerproject.com/2018/07/31/the-power-enclosure/https://mowerproject.com/wp-content/uploads/2018/07/img_3767-e1533091409466.jpgIMG_3767The wiring to the battery terminals. The Posi-Locks make for an excellent connection, but you have to strip the wires to just the right length.https://mowerproject.com/wp-content/uploads/2018/07/img_3766-e1533092192825.jpgIMG_3766The XLR charger plugged in. https://mowerproject.com/wp-content/uploads/2018/07/img_3765.jpgIMG_3765https://mowerproject.com/wp-content/uploads/2018/07/img_3764-1-e1533090964670.jpgIMG_3764 (1)The completed power electronics enclosure.https://mowerproject.com/wp-content/uploads/2018/07/img_3763-1-e1533090431936.jpgIMG_3763 (1)The power electronics components. Things are starting to take shape.2018-08-12T21:15:04+00:00monthlyhttps://mowerproject.com/2018/07/17/xlr-charger-arrives/https://mowerproject.com/wp-content/uploads/2018/06/multimeter_on_charger.jpgmultimeter_on_chargerhttps://mowerproject.com/wp-content/uploads/2018/06/img_3737-e1530242277970.jpgIMG_3737The battery charger label. The 24V is really 27.3V.2018-07-14T03:00:01+00:00monthlyhttps://mowerproject.com/2018/07/16/paper-plots-you-dont-need-an-nc-machine/https://mowerproject.com/wp-content/uploads/2018/07/img_3757-e1531536749441.jpgIMG_3757A paper plot for one of the enclosure sides.https://mowerproject.com/wp-content/uploads/2018/07/img_3750-e1531536212660.jpgIMG_3750Use lots of tape: you don't want the paper plot moving after you've drilled half your holes!https://mowerproject.com/wp-content/uploads/2018/07/img_3749.jpgIMG_3749https://mowerproject.com/wp-content/uploads/2018/07/img_3748.jpgIMG_37482018-07-14T02:58:20+00:00monthlyhttps://mowerproject.com/2018/07/13/machinists-im-sorry/https://mowerproject.com/wp-content/uploads/2018/07/img_3754.jpgIMG_37542018-07-14T02:17:30+00:00monthlyhttps://mowerproject.com/2018/06/27/how-not-to-build-a-robot/https://mowerproject.com/wp-content/uploads/2018/06/twistercow-e1530076993696.jpgtwistercowYour compass is going to have a bad time.https://mowerproject.com/wp-content/uploads/2018/06/sabertooth2x32.jpgsabertooth2x32https://mowerproject.com/wp-content/uploads/2018/06/img_1193-e1529988432840.jpgbad_robotCan you spot the problems in this picture?https://mowerproject.com/wp-content/uploads/2018/06/bad_robot-e1529986106111.jpgbad_robotCan you spot the problems in this picture?2018-06-29T03:48:23+00:00monthlyhttps://mowerproject.com/2018/06/28/an-ounce-of-planning/https://mowerproject.com/wp-content/uploads/2018/06/pixhawk-with-4-14s-hyb-bec-and-200a-sensor.jpgPixhawk with 4-14S HYB-BEC and 200A sensorhttps://mowerproject.com/wp-content/uploads/2018/06/wiring1-e1530161785420.pngwiring2022-03-19T03:38:54+00:00monthlyhttps://mowerproject.com/2018/06/24/__trashed/2018-06-25T04:23:05+00:00monthlyhttps://mowerproject.com/2018/06/22/thanks-rod/https://mowerproject.com/wp-content/uploads/2018/06/jazzy-select-6-e1529644430121.pngJazzy-1103The Pride Mobility Jazzy 1103 Electric Wheelchair.https://mowerproject.com/wp-content/uploads/2018/06/andrew-neel-182861.jpgPlaceholder Image2021-01-31T06:03:32+00:00monthlyhttps://mowerproject.com/contact/https://mowerproject.com/wp-content/uploads/2018/06/person-smartphone-office-table.jpegPlaceholder Image2018-06-24T06:33:52+00:00weekly0.6https://mowerproject.comdaily1.02022-07-26T03:39:11+00:00