I did something similar with The Honey Badger 2.2 where there was a sheet of Aluminium over a layer of HDPE. Had I bolted it down properly, it would probably still be with me but it seemed to hold up quite nicely against non-spinners.
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I did something similar with The Honey Badger 2.2 where there was a sheet of Aluminium over a layer of HDPE. Had I bolted it down properly, it would probably still be with me but it seemed to hold up quite nicely against non-spinners.
Thanks may give this a go. Will have to think about best way to fix them.Quote:
Originally Posted by Ocracoke
Having a bit of bother with the servo controlled linear - I took this from the Barróg thread
[QUOTE=RogueTwoRobots;468452]On point number 2, the easiest way would just be to use a servo to turn on a couple of microswitches, one for each direction. It allows you to control forward and back from one radio channel and the stock actuator motor will have a low enough current draw to not require any additional relays etc. Here's a setup in its simplest form; I usually tend to just hot glue the switches onto the sides of the servo and wrap a cable tie around them, but you may prefer a more robust/maintainable/aesthetically pleasing alternative :)
Attachment 6852[/QUOTE
I assume I wired it wrong. But not sure how I identify the right terminals.
Attachment 8170
My expectation was without either microswitch engaged it would be off. With one or the other polarity would be reversed.
I possibly toasted them in the process of getting it wrong.
The switch is a Z-15GW-B
The pin nearest the rocker is 1 - COM
Centre is 3 - NO
Nearest switch extended arm 2 - NC
Advice appreciated as my electrical know how is poor at best.
I think if you connect on each switch:
pin 1 (COM) to the motor
pin 3 (NO) to batt+
pin2 (NC) to batt-
I don't think you will have blown them up :) as long as you keep the motor connected across the 2 common pins, you should be ok.
Let me know if this works, or if you want me to draw a circuit diagram.
Paul
you're a genius! that works thanks very much
Thanks to the help of Paul I got the linear control working. At least this mock up, which powered a small 12V motor. The idea is to make a sandwich with some polycarbonate as the bread and the microswitches as the filling. Conveniently the mini servo I am using is just the right height to align with the arms.
Attachment 8192
Attachment 8193
I need some long 4mm bolts and some longer 1.5mm bolts, and in the final version the polycarbonate will shield the arms too. (Pictures updated with bolts fitted)
Got a few deliveries this week.
Bolts, nuts, titanium plate, polycarbonate
I am going to make the top mostly from polycarbonate as it's light, also it's cheap to replace so no big deal if destroyed after each event. I'll add reinforcement behind.
Did a little more work on the electrical system. Configured the buck voltage reducer to put 18V to the lineac.
Added a 'live' light, a 100A fuse for lipo and a kill switch/jumper
I am making a polycarbonate lid for the bucky and adding a fan to be sure it can handle max load.
Here's a video of my lineac controller working
https://youtu.be/5Evv8xzeZWU
Its looking really good :) I am excited to see it all together.
Thanks very much.Quote:
Originally Posted by PaulusSmallus
I added some titanium plate to the front instead of that bit cardboard ;). It weights in at 13.02kg so once the ramp is fitted it's going to be a bit over but lots of opportunities to lower weight.
Having some electrical issues. Got it all wired up, motors spinning, lineac running, but something is not right.
What is wrong with it?
I am not 100% sure.
The power is down.
The Feathertwo is making a tone when operating the motors (I think sound is coming from the ESC)
It moves forward and back but not turning when on the ground, but works properly when on stand.
I have 3 fuses all at moment under sized for testing and none are blowing. A battery fuse 30A, a ESC/motor fuse 30A and a lineac fuse 15A.
Very odd. I sent a PM to Rapid Rory
Two thoughts:
My shockingly bad soldering (the kill switch was getting very hot)
The RX is sending bad signals to the ESC
Is the kill switch getting hot when you try to move it on the ground, or are you meaning it got hot when you soldered to it?
Do you have a multimeter?
It gets hot when running. Actually smoked.Quote:
Originally Posted by PaulusSmallus
It's a anti-spark XT90 with awg10 wire across the pins.
Yes I have multimeter
Found first issue. A connection in the XT90 kill switch was not sound so could only carry so much power before it maxed out. On the ground the motors pulled more current so they stalled.
There is still a tone from somewhere. I think the ESC but seems ok.
Running up the motors at higher speeds the chain jumped. I need to fit a tensioner, I thought I may need to. I have some ideas.
Also played with the trim. Not really sure what I am doing here but moving channel 1 to the right of centre seems to have aligned the drives a bit better. Once the chain tensioners are fitted I'll give test it on the ground.
Still need to fit the wedge ramp too
I has this issue on my FeatherTwo, it is the trims that need setting on the controller. My axe on The Honey Badger 2 used to provide a little bit of power in reverse so adjusting trims made it stop making that noise.Quote:
There is still a tone from somewhere. I think the ESC but seems ok.
Fitted some tensioners. I had ordered some track bike tensioners in case.
Attachment 8196
These worked really well! So I thought I'd give it fill power on the stand.
WhirrrrrrrrrrrrrrrrrRRRRRR
CLUNK!
Chain off on the other side. But how? So much tension?
I could see the chain had hit the frame.
Attachment 8197
But the gear should not be that far over. Time for a total disassembly :(
Initially I thought the bolt had sheered off.
Attachment 8198
But no. I'd only used regular nuts when I didn't just build up, planning to swap them out for locking nuts before finishing and I'd forgotten.
But with the whole front, body, wheels out no video today.
But I'll take the chance to make some improvements and lose some weight.
Drilling the wheels
Drilling the floor
Cutting a piece out the floor
Widening the wheel slots
Swapping out nuts for locking nuts
Tightening up
Need to get this done fast as I have not yet tested the lifting arm.
Today I stripped it right back.
I cut a 12mm strip off the front and sides leaving some pieces as a ledge for the HDPE armour.
Widened the wheel slots a bit,not much weight saved there.
Also drilled a heap of 10mm holes in the base and some 50mm holes in the HDPE sides and back.
I also cross drilled all the rubber of the wheels but to be honest I saved very littleweight. I think the weight is in the hub.
While I had the wheels out I checked the fitting and replaced those pesky nuts with locking nuts.
Refitting the wheels on the axles took about of work but I am happier in their location,and the clamps are tighter to stop movement when rotating
Swapped out the motor retaining nuts for locking nuts.
Tightened everything else up.
I should have shed perhaps 200g. Fingers crossed.
Refitting it all back together now. Fitted some of the pond filter foam around the electronics, and under the battery. Tidying up some of the cabling.
Tomorrow I want to refit the shell,and test everything still works.before bolting it all in place again. Then it's fitting on the front armour and building and fitting the ramp, including the self-righteous mechanism, and sides.
I could do with a day off work.
Having a total nightmare!
No matter what I try with the tensioner the chain is jumping. Tried shortening chain and it would be too short.
Tried the tensioner lifting from below today. Same problem.
Spent hours today on this, beginning to think I may need to try something completely different.
It's a shame as I received the Grantham email I citation today too :(
Anyway no time to write more. Back to the Robot Shed for me
I can only think of either the chain being out of alignment or a bent tooth on one of the sprockets.
I think I have cracked it. - Alignment.
There was a wobble in the wheels, where the sprocket was bolted to a spacer onto the hub. Also the drive sprocket and the wheel sprocket were not aligned precisely. Now cumulatively this can't have been that much a few mm. But I ran it full speed forward and back a few cycles no problem. Going from max power to stop does generate a clunk but that can be the chain going from teapnsionnone direction to the other.
Again I'll add photos soon at the momentum need to get back and repeat process on the other side!
I think it's fixed. Tests at full speed on both drives, and rotations. All tests on the stand but I am fairly confident it's fixed.
Here's a video of it at low speeds. Didn't want to be standing in front when this thing spins up, just in case!
https://youtu.be/zpb_7Y5KODk
I am not as happy with the right hand side as the left, ( as you look at it) but time is of the essence and I don't have the hours left to be pedantic.
After this video I laid out the electronics again. Finalizing the positions, I am using the filter foam under the battery and around most of the sensitive stuff. The battery will need some form of retainer but I'll address that once I have the front on and the lineac hooked in properly. That's my main task for tomorrow.
Disaster!
Still throwing the chain. I am getting desperate now.
The chain is so tight I struggle to fit it, yet once on it flexes enough to derail.
Clearly after testing on the stand and it worked, then simply fitting everything else back in and failing meanwhile too sensitive for combat. One knock and it would fail.
I think the only thing I can try now is to move the motors them selves.
Fit the chain and then bolt in the motors so there is no give at all.
With a job it's hard to imagine I can achieve this plus the open topics in time for the weekend now. Grantham is looking doubtful :(
did you calculate the correct centre spacing for the axles when choosing chain length? The best method would be to fit the chain then the motors down.
not the one im looking for but this will help:
http://www.botlanta.org/converters/d.../sprocket.html
Quote:
Originally Posted by Roboteernat
Thanks for the input. I am such an amateur, I'd originally considered having the drives mounted so they could slide back and forth to take up tension before fixing and this would have been a lot better.
Trying to continue now at this stage is more effort, but I will try.
I tested all the electrics again and it's all good. Still need to build the ramp have around 600g left for that which seems short but we will see.
For what it's worth, featherweights at heavyweight events aren't really weighed. There's a good deal of leeway as the meleés are just for fun so no-one is going to be nitpicking if it's a few grams overweight (or even a few hundred grams, unless there's a competition run). Hopefully this will free up some time for you to put towards the drive issues.
Is there any side-to-side wobble on the wheel sprockets or motor sprockets? This will be a contributor to throwing chains, with the other one being the sprockets mounted eccentrically (not concentric to the shaft) so that the tension will increase and decrease as the wheel rotates. It's a difficult thing to get right without decent tooling. The side to side wobble can sometimes be sorted with strategically placed washers, but eccentric mounting is harder to rectify. Having chains really tight isn't good, you want a little slack in them but obviously this is exacerbating the problem too. Not much to do except keep plugging away to find the right positioning that gets it working :-|
Thanks Jamie - I really appreciate all the support and encouragement from everyone. Been a tough few days felt like giving in a few times and starting again.Quote:
Originally Posted by RogueTwoRobots
But finally it seems I have it sorted ( but I thought I had it sorted before). Took her for a spin around the patio, controllable and fast. This was with the electronics just laid inside as a quic test.
Assembled fully again and now the ramp is rough fitted to the linear actuator. Sorry no pictures again but they'll come.
I'd hoped to add some fun design elements but not looking like I'll have time. That said this time yesterday I thought I'd never be ready.
Building robots is an emotional rollercoaster.
Just wait until it is in the arena. I find myself getting really nervous beforehand and doesn't really pass until about a minute after 3...2...1. ;)Quote:
Building robots is an emotional rollercoaster.
Today is not a good day :(
Alligrater was fully assembled and being tested when the chain came off yet again! Repeated hard testing on the bench seems not to be the same as driving it on the pavers.
It doesn't stop there however, as the self righting mechanism also fails to deliver. The motor was rated at 17.5N @12V which I imagined would lift the 13.6kg but it's no where near the power needed I failed to consider the lever point reducing the effectiveness. Even though I am running 18V.
Finally the weight (though this was not critical for the event) was 14.12kg so 500g over.
I won't be going to Grantham. Living in Scotland it's too far for what is most likely to be 5 seconds of combat with this build.
That said I am not giving up. But it's back to the drawing board.
Here are pictures of the current design:
Front view ramp open to vertical
Aluminium C bar
Attachment 8205
The polycarbonate sheet has a little give to allow it to scrape the floor
Behind that is some grade 5 titanium
The idea was to be able to replace the polycarbonate or have different designs depending on opponent
Attachment 8208
At the back you see the alive light
Had to drill the holes for weight saving
The kill switch/jumper is an anti-spark XT90
Attachment 8209
Wedge fully open at I estimate more than 120° from the rest position
Trying to cheer myself up. Looking for positives. If I go quiet next few weeks it's not me quitting but I have three work trips and then a summer holiday so could be August before I can be very active again
Oh mate, sorry to hear. It's looking really good as well.
It's a shame about the chain and self right, but at least the rest of the build looks great.
For the LinAc, I have been using a free trial program called Mechanical Expressions. It's 2D, and the modelling is done with simple nodes, lines and coordinates. Add a load of 13.6kg, and it'll tell you the force on the LINAC.
If you decide to give it a try and struggle, I can try and lend a hand.
Back from my holidays and back to the drawing board and time for some reflection.
Lessons:
The scooter motors are too heavy for anything but a push in this class (as I was advised)
Got the electronics working woohoo!
Realised chain drives are a lot tougher to get right than I expected
All the nuts, bolts and washers add up to weigh a lot more than I expected
Due to the number of failings I am going to park this concept and try something new