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Ultimate running companion

Better than human

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Human runners telling you to get lost because you're not rich, bald, & fat? Need a way to carry your junk, get video of your running form, pace your workouts, light your path, play music?

When it was introduced in 2013, it was a modified G-buggy no-one cared about. 3 years later, it was still no more than an RC car, but self driving car startups saw their valuations explode & anyone in Silicon Valley who saw this machine suddenly wanted to write a $65 million check. Should have really driven it down Sand Hill Rd & fielded buyout offers.

The key development was the remote control.

The object of the robot is manetaining a constant speed & heading on its own.  This is just automated enough for a lion to drive it with 1 paw.  The journey began in Jan 2014, with a $40 G-Buggy the lion kingdom got for free:

It was a very poor at setting a pace, couldn't carry cargo, but could carry a camera.  There was no easy way to measure speed & the steering was binary.  With enough tuning however, the steering could be made proportional enough to hold a heading.  

The steering mechanism was an interesting reduction of a servo into a spring that centered the wheels & a clutch plate that applied a steering force proportional to the speed of a motor.   The controller it came with could only do binary steering, but with a fast rate sensor & feedback loop, the steering could be made somewhat proportional. 

The inner clutch plate & outer ring it pressed against while spinning, but not while stationary.

With a constant voltage applied to the traction motor, it achieved poor speed regulation but infinitely better than lions trying to pace themselves.  

The final form of the 1st model.

Several models came afterwards, as budgets increased, culminating in the Tamiya Lunchbox.   The steering was finally proportional & the speed could finally be regulated.

Attempts to make it self driving all failed, for reasons startups are too familiar with.  

Key to making it all work was a paw controller.  Proportional steering & throttle would be nice, but weight & durability dictated binary tact buttons.  China simply never made a durable, compact, proportional sensor.

The  final design had 2 buttons for slow steering, 2 buttons for fast steering, 1 button for throttle.  This was proportional enough for all needs, with the computer automating speed & heading.  1 switch controlled reverse.

  • Servo testing

    lion mclionhead09/07/2018 at 05:39 0 comments

    So paid $30 for 4 new servos, reflowed the QFN's solder joints, & made a servo exerciser to thrash it all night.  Naturally, it would never fail on the bench, but the new servos alone stood a good chance of reviving it.  The last order of standard servos was 2001.  They were $6 Tower Hobby branded, but shipping was much lower.   Those hobbyking servos are now $5, but shipping has followed inflation. 

    Signs started pointing to a glitching battery connector crashing the microcontroller on the servo.  The mane CPU also had glitches, but didn't lock up.  The servo may just lock up under certain power glitches.

    After cleaning all the battery connectors, the Trackstar was revived & didn't crash again for 400 miles. So it's a lot more sensitive to electrical noise than a brushed servo. It must run at a much higher clockspeed. 

  • New tires & servo death

    lion mclionhead08/26/2018 at 23:24 0 comments

    The rear tires lasted most of the year, but eventually wore down enough to become front tires.  Nylon straps have done the best of any material on the front tires, despite the problems getting them on.  The nylon has all come from an old camera bag which the lion kingdom twice ran 32 miles with.  Old lions wouldn't do such a thing, because there are lighter solutions.

    Getting them on has best been done by tacking on a quarter of the strap at a time with high airflow.  The high airflow sets it quickly.  Then do a 2nd pass sealing the gaps.  It still needs 24 hours to  cure.

    After 2 months, the $60 brushless servo died & it went into the street.  The death was intermittent, as it briefly came on again.  Back on the bench, it managed to still have a fault.  All the voltages were normal, with no voltage going to the MOSFET gates.  Power cycling it a few times in the street didn't bring it back, but it did come back after a power cycle on the bench.  Nothing that suffered mechanical wear seemed to be worn out.  It was a microcontroller that had become flaky.

    It's a Silicon Labs F330, 8051 core.   Dave would check all the pins & try to fix it.

    After all the servos, there's a real need to build a servo from scratch to last forever.  The $60 one has enough useful parts to work again with a custom board, but this would be a significant investment in a rare time when the lion kingdom's time is actually worth more than a servo.

    Expensive, high performance servos have consistently died much faster than cheap servos.  The longest lasting might be the Tower Hobby brand from 20 years ago.  Futabas are in the middle.  Servos might have too many moving parts, moving too fast, in too little space.

  • Wheel alignment woes

    lion mclionhead07/11/2018 at 22:52 0 comments

    After some hard driving with high speeds & heavy payloads, the transmission was dried out in no time.  The mane issue was high power consumption with no payload & high wheel wear, so the last alignment with a full payload didn't work.  Another round of 1.4 mile repeats with no payload also failed.  Tried charging without the balancer.

    Definitely more erratic charging totals when the balancer wasn't used.  Temperatures over 93 & the lack of payload could have also done it in.  The next step is recording throttle PWM over a smaller route.  It should be much easier, but much less sensitive & still require a full charge.

    The easiest solution is a serial port interface which allows starting recordings in RAM & dumping the recordings.

    Eventually just tweeked it over many 10 mile runs.  The range came back to 15 miles on a 4500mAh battery, depending on terrain & payload.

    Lion tip:

    Run with the robot on your left.  It drives a lot straighter than a lion can run, so tends to keep the lion on the right & piss off fewer bikers.  

  • July 4 results

    lion mclionhead07/08/2018 at 06:43 0 comments

    The final cruiser swore allegiance to the god emperor & chief.

    A test drive didn't reveal any problems.  The phone got better radio reception than the 30 year old FM banger.

    The 8 year old glow stick barely lit up.  Either it expired or lion vision has deteriorated too much to see anything since using those as a kid.

    The fireworks were pretty minimal.  It was an overcrowded street with limited visibility & humans who were too busy yelling at each other to notice their god emperor.  It was a pretty awful place for a fireworks show.  The speaker wasn't needed, since they had barely audible music & the radio station didn't seem to be broadcasting the soundtrack, anymore.  The FM banger came in a lot better in downtown.  Then, during the 1 mile drive from the show, the $60 steering servo died.  The metal gear came undone from its servo horn.  

    This part never got threadlock because of its tendency to crack plastic.  The next idea was to threadlock just a bolt in the metal gear, let it dry, then install the servo horn.  This is why you should never overhaul less than 50 miles before an important mission.

    Also, the shoelace strap got ground up a lot faster than last time.  Glued another shoelace around it, but a way to bind a wider strap to this conical section must be found.  Kevlar rope is increasingly tempting.

  • The July 4 cruiser

    lion mclionhead07/03/2018 at 07:40 0 comments

    It's time. Socialism sux, but it's fact everywhere in the world. If the lion kingdom was in Thailand, it would use a Thai flag, but if it was in England, it would use a 13 star US flag.

  • The brushless servo arrives

    lion mclionhead07/02/2018 at 04:53 0 comments

    The $60 TS-940HG was the only one in stock.  They sure made a big deal about the helical gears.  

    It's heavy, but fast.  Standby current is no different than normal servos.  

    CNC milled case.

    A 3 phase motor with 3 hall effect sensors, but not anything you can get separately.  

    The servo saver was the only thing which fit & could reach the pushrods.  There were no changes needed in the feedback.

    Instead of electrical tape, applied duct tape to the transmission with small electrical tapes just over the holes.  This gave good protection without contaminating the oil.

    In other news, the nylon straps were a failure.  They were too wide & inflexible to get around the conical wheel shape.  A conical section from a sheet of fabric would do it.  Back to shoe laces.

  • July 4 test 1

    lion mclionhead06/21/2018 at 10:02 0 comments

    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.

  • July 4 cruiser

    lion mclionhead06/19/2018 at 19:03 0 comments

    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.

  • Another dead servo

    lion mclionhead06/02/2018 at 06:54 0 comments

    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.

  • Refrigerated transportation

    lion mclionhead05/30/2018 at 03:03 0 comments

    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.

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