Ultimate running aid

With the final surviving DM-01 revived again, there would definitely be fire, noise, & mane hair.

The DM-01 amplifier required 13V, so replaced it with the 12V TDA1517 amplifier which formerly pumped tunes on the lion kingdom's city robot, many years ago.  Mounting it in the enclosure involved packing material.  The gain was fixed to 5:1, leaving only the walkman to control volume.  With this much stripped down, it was still a brick but lighter than the 3.1lb burrito bag the lion kingdom drove 3 miles with.  

A 7.4 mile drive with speaker, walkman, & shirt burned 444mAh/mile.  The speaker burns 200mA.  It could only go 6 miles, while having enough reserve for the show. Radio reception definitely requires the flag pole.  PWM noise was horrible, manely when climbing hills.  It definitely needs a variable gain for any long term use.   Besides the noise issue, the sound was far superior to the bluetooth speaker.

It also made the lion kingdom ponder sticking on some light sticks & LED flashers, but nothing custom.  It should really have some patriotic music during the drive in & out.

If any fireworks were still within 10 miles, the bluetooth speaker would be a no brainer, but with the plan being a drive to within 3 miles of the show, it would be a shame if someone else had a louder radio.

The radio still works, but the tape mechanism is well & truly gonesky. It seems to have rusted during the year the lion kingdom was in a 1st floor apartment. The plastic buttons are remarkably still intact. The radio is outstanding. The lion kingdom used it from 1991-2000. The cheapest modern radios are still over $10. It will always require the useless tape section for an audio amplifier. An alternative audio amplifier would take more space or cost over $10.

The idea was to hook it to the rover's speaker for July 4 & drive it down to the fireworks. Old fashioned radio is much more reliable than trying to get the soundtrack on the lion kingdom's ghetto phone plan, but helas, all the fireworks within rover range are gone for good.

After all the other servos died from pot glitches & broken gears, a servo finally died from something that a brushless servo would fix.  It stalled & burned out the H bridge.  It was brand new, but came from Hong Kong.  

Ice below should do a better job than ice on top, since that's how fish are frozen.

Finally cracked open the ice budget & attempted the 1st refrigerated transportation. This requires going both ways with ice blocks, significantly reducing range. 2 ice blocks were quite heavy, but it didn't show a significant increase in tire wear after 10.7 miles.  Power consumption increased to 328mAh/mile.  The weather started hot & got cold by the end. Sandwiched the salad between the ice blocks. The top ice block finished more melted than the bottom. The salad arrived still cold, which isn't very conclusive unless another test is done without ice, in the same weather. Ice cream definitely needs to be tested.

Whether ice on top or ice on the bottom is more effective is unclear. Most heat should get in from under the robot, but cold should travel down.

A newer tire set covered in E6000 adhered shoelace was indestructible & broke 280mAh/mile.  Alignining the wear point on the shoelace seems to be the key.  The next step would be common nylon straps, then kevlar, which would be military grade.  They're not wearing out fast enough to do meaningful testing.  Together with the shapelock reinforced wheels, it's become a truly durable system.

Another 11 miles with a heavy payload shredded the shoelace coating & burned 360mAh/mile.  Interestingly, 11 miles with a light payload left the shoelaces intact & burned a record low 286mAh/mile.  A fabric coating might have much lower rolling resistance than rubber, though insufficient life.  It also might be the fabric which shredded wasn't covering the entire contact area, so it was getting lifted from 1 side.  

If money was infinite, experiments with kevlar fabric could be justified, but the next focus was garden hose rubber.  It couldn't conform to the wheel at all & was much heavier, so the lion kingdom tried tiles.  Any rubber pliable enough to conform to the tire is probably going to be too easy to shred.  Kevlar coated tires just sound badass & might actually work.

There's enough E6000 in the $4 tube for 1 more coating.  The E6000, liquid electrical tape, shoelace, & hose rubber have already been far more expensive than just buying new tires.

Went 10.75 miles at 386mAh/mile with dual batteries & the gopro tower, but it cost tire rubber.  A CA glue coating wore off or fell off.

It was time for some other materials.

After 8.6 miles, a common shoelace adhered by E6000 did better than any other material.  Although the adhesive itself ground off & the fabric was quickly grinding off, it was the 1st sign a protective coating could definitively stick to the tires.  The solution was now just a matter of sticking a denser rubber on.

Sadly, the paw controller died on this drive.  After switching to phone control, the screen locked up & it drove into the middle of the street.  Must remember not to use phone control near traffic.

So the right turn errors were from the servo horn jumping a cog & getting cracked, not the pot.  It happened for some time, but intensified with the camber adjustment, because of the increased rolling resistance.  There are servo savers & a return to feedback problems or going back to stock camber & tire wear.

The direct servo link is a huge benefit to video quality & lions are more interested in efficiency, so the decision was made to return to the stock camber & apply liquid electrical tape to the tires.  The mane problem with a more robust vehicle is the increased weight of batteries, so efficiency is a goal.  The other problem is starting a new learning process when most everything that can go wrong with the lunchbox has been found.  Fixing wheels & transmissions isn't the only thing lions do.

$7 later, there was this.

This was very expensive, but worth trying.

Another 1.4 mile test, but with no cargo & speed reduced, dropped back to 328mAh/mile & theoretically the most efficient toe in should be the same in both camber settings.  

Another 9.45 miles with 2.6 at 7m12s/mile flaked the coating completely off.  That burned 2775mAh or pretty much what it was before lowering the suspension.

At least, it showed the friction was concentrated on a small part of the edge & this small contact area was probably the key to great efficiency.  The toe in with stock camber was the same as the best efficiency with vertical camber, so there wasn't a cross talk between camber & toe in.

Did 1.4 mile repeats in the apartment complex, with different wheel alignments.

It was very inconsistent, but had a bit of a local minimum.  A 6.3 mile drive with the spherecam & 2 batteries burned 519mAh/mile.  Looks like either increased contact area or bad transmission fluid is killing it.  If the wheels wear down as fast as before, it'll definitely go back to the stock camber, but it might be worth just letting the stock camber wear them out in exchange for longer range.  It'll probably go 400 miles with tire rotations, which is 1/2 as far as shoes can go.  Another idea is coating the wear pattern in an expendable but cheaper coating.  Rubber coating paints abound, for a price.

The new servo continued to show problems with its center point drifting right, so it wasn't a bad pot.  It could be pushrods slipping, a bad connector, or voltage going off.  The left wheel tends to turn more right while the right wheel stays centered.

A new wheel arrived, so did the teflon treatment, whacked it in & realigned everything.  The wheels wore down the middle instead of the edges, but it burned a horrendous 460mAh/mile.  It never burned that much with even a brushed motor & stock suspension.

The gyro started glitching, so cleaned the contacts & it appeared to be recovered.  Washing the vehicle seems to get contamination in the contacts.  

Toed in by 1 turn & it burned 425mAh to go 1.17 miles before the servo started centering on a right turn.  The key does seem to be toeing in.  Maybe the forward motion pushes them out or the camber is still off enough to require it.  1.17 miles isn't long enough to determine efficiency.

Toed in another 1/2 turn & replaced the servo again.  Pots seem to go more often than brushes.  It could be water intrusion from truck washing.  The next 7 miles burned 3206mAh or 458mAh, so it could be the larger contact area on the tires.  2 miles of that were at 10mph, but still.