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Forum Index : EV's : Hybrid remote lawnmower
| Author | Message | ||||
| Alasdair Regular Member  Joined: 12/01/2011 Location: AustraliaPosts: 62 |
Hi all I am collecting parts to build a hybrid remote controlled lawnmower, which when completed will allow me to mow a very steep (30-40 deg) bank. I plan to use a two stroke pope motor that I have, as this type doesn't fuss about running at extreme angles. The motor will run the blade disc and a small car alternator which I have ready to go. I plan to run four gearmotors that I salvaged from a wierd mobility scooter with the front two reverse linked to the rear two to facilitate four wheel steering. The motors will be steered via a small servo of some kind. (still trying to find this part) I plan to vary the field voltage to the alternator to facilitate speed control and regulate & charge a small battery pack for the RC and steering servo. No engine throttle needed as the pope is governed. I'll use a rover SP deck as it has a belt hole behind the crank which will allow easy mounting of the alternator. The wheels will have negative camber, wide track and nobbly tyres to keep CG down and minimise rollover, but I'll also fit a couple of hoops to help it roll back onto it's feet if the inevitable happens. I've nearly slid under the self propelled mower too many times for comfort on this crazy bank. One neighbour wants one if it works for a gully on his block, however it runs to near vertical about two thirds the way down so I think he'll need tank tracks and lots of luck.. Amc-elec |
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| VK4AYQ Guru  Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Alisdair I would suggest a small linear actuator for your steering servo as they have a digital feedback built in. It may be useful to add a heavier cutting disk to get some gyro stabilization, as I found out with stock cars the hoops just help it keep rolling until it hits something, better with a active roll arm that can right the mower, using another linear actuator. You can get a small speed control on fleabay for cheaper than you can build one, one each side with digital to replace the pot and you got it all. All the best Bob Foolin Around |
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| Alasdair Regular Member Joined: 12/01/2011 Location: AustraliaPosts: 62 |
Hi Bob, I do have a linear actuator (LA30 Linak) which I may try, the only problem is it's a bit slow at 12v, I'd have to stop and wait to turn, I think I could gear the linear motion up (very short steering arms) or use a counter lever. Is your twin speed controller idea based on skid steer? I was going to build a big servo using a Bodine gearmotor (ex paristaltic pump from a dialysis machine)but I can't seem to buy a driver chip for digital proportional control. I was going to bust open a little rc servo and just upgrade the driver transistors, The drive motors will probably need up to 15-20 Amps each, worst case scenario (stalled against obstacle) but those cheap speed controllers are good value. The field option will ramp the full output (85 A) from the alternator so is pretty bulletproof, but I have to regulate and store for receiver and steering.. Your idea sounds better, but skid steer will probably result in a downhill drift by the time it turns. Regards Alasdair Amc-elec |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Alasdair I think the way you turn on a hillside is important as I found out driving a skid steer dozer LW 16 many years ago. Because you are mowing in both directions it isn't a 180 deg turn, and run the tyres at a low pressure for a better traction footprint. I think it would be a lot easier than trying to rig up steering. All the best Bob Foolin Around |
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| Alasdair Regular Member Joined: 12/01/2011 Location: AustraliaPosts: 62 |
Hi bob, I always do things with maximum engineering challenge divided by minimum time and utilize as much junk from the shed, topped up regularly by local tipshops, as possible. I just realized I have a snapper ride on mower with a good cutting deck (appx 28") but stuffed transaxle buried in there. I could easily build a frame with a wheelmotor on each corner, linked with chains for steering. This would allow 270 deg steering, or enough to rotate on the spot. I would need to dry-sump convert the motor, but the extra cutting deck width would be worth it, however it will be heavy, wider track, and be more likely to destroy itself if it tips over. A mercury switch with oil pressure switch on ignition circuit is probably some insurance. I just don't want to break the wheelmotors. Maybe I just stick to the little 18" pope. Keep it light and nimble. The wheelmotors have a 6" rims with fat 4" knobbly tyres so it would be good to lower pressure. I was going to swing the front axle about 15 deg to keep all feet on ground, but it puts C/G on three points instead of four so I don't think I will. All wheels driving should be enough if one wheel finds itself dangling. I won't electrically differentiate the motors for this reason too. Skid steering is sounding better all the time. Regards Alasdair. Amc-elec |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Go for it mate, The old dozer I had was four wheel drive with chain box on each side, it never worried about one wheel swinging in the air for a bit, if the tyres are a bit under inflated they will compensate to a degree. I think the little pope sounds like a good starting point, if all works out as planned go to bigger and better later. the mercury switch on the ignition sounds good, at least you wont have to dodge a disk with sharks teeth if you have to right it manually. All the best Bob Foolin Around |
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| Alasdair Regular Member Joined: 12/01/2011 Location: AustraliaPosts: 62 |
Hi bob Good plan, start small, I did actually lose that Pope mower once after a couple of bounces it flipped over and ended up on it's side before finally spluttering to a stop. I remember thinking 'sure glad I wasn't down there trying to dodge that! At least with gearmotors there is no freewheeling to contend with. Regards Alasdair. Amc-elec |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I have a couple of ride on mowers and always thought it would be a cool project to convert one to remote control. But then I thought, I would have to walk around behind it so I could see where it was mowing. Then I figured I could sit on the mower, so my legs didn't get tired. Then I noticed the mower already had controls I could reach from the seat, so I didn't need a remote control after all. But seriously, at my old property, it was very hilly and on a few occasions I almost fell off the mower. Scary, I can see how accidents happen, and end up with a mower on top of you. Thats when a remote control would have been handy, I could stand next to the mower while it tries to cut the grass on some dangerous angle. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Glenn Don't go near the edge of the range up there and you will be alright. Bob Foolin Around |
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| Alasdair Regular Member Joined: 12/01/2011 Location: AustraliaPosts: 62 |
Hi all, I do use the ride on for most of the lawn but the remote mower is just for the 45 degree bit, which is hard enough to walk up, let alone the 90 passes it takes with a self propelled mower. My ankles will be very happy to never do that again. I can sit back, watch the mower do all the hard work, and listen to my iPod. Alasdair. Amc-elec |
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Poss Newbie  Joined: 27/09/2009 Location: AustraliaPosts: 30 |
Fence it off and put a sheep in there and call him "Victa" fully self propelled,zero turn, low emissions and then invite him to Sunday lunch when he's done.  A brave man may not live for long, but a careful man does not live at all. |
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| Alasdair Regular Member Joined: 12/01/2011 Location: AustraliaPosts: 62 |
Ha, you Poss must be psycic, we were given three ex pet sheep, named Victa, Rover and Briggs, two died of snake bite and the lone survivor went nuts, or more nuts in sheep terms so we gave him away, but they were escapologists and a total pain in the backside. We now use conventional mowers as they don't try to get into the house, or sleep on your steps on pitch black nights, or huddle on the verandah to watch you inside.. Just put petrol in, pull cord, mow. Amc-elec |
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