Ultimate running aid

Eliminate everything from running but the running part.

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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 while doing something else.  The journey began in Jan 2014, with a $40 G-Buggy the lion kingdom got for free.

This was the seed of the idea.  The lion kingdom would probably have never developed the complete robot if it wasn't for the original free G buggy.

It was a very poor at setting a pace, couldn't carry cargo, but could carry a camera.  The potential for documenting runs was there.  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.

The stick was further refined with 900Mhz frequency hopping radios, 4" packing tape to insulate the switches from sweat.

The current system is a modified lunchbox with a very large container.

Suspension was lowered.  Wheels were reinforced.  Tires were wrapped in nylon. 

Current mail order parts which have yielded the best results, after thousands of miles:

bearings    10.48

Lunchbox kit    147.2

motor discontinued

1:10 2400kv size 540 35mm diameter 3.17mm shaft.  The 2848 descriptor is not reliable.

bec    6.86

Brushless servo    50

battery  ...

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  • Yet another carbon fiber attempt & failure

    lion mclionhead9 hours ago 0 comments

    with a reversion back to good old aluminum. Carbon fiber just needs better farsteners. Duct tape stretches over time, allowing the pole to flop around. Aluminum can be bolted, making it solid but heavy.

  • Another dead CC1101

    lion mclionhead7 days ago 0 comments

    This one died 5 miles from home, so it was another 5 mile walk back with the robot using its bluetooth interface.  It was here when the lion kingdom realized the bluetooth interface should have fully proportional steering with very low deadband & a way to detect when the driver's paw stops moving due to a GUI bug.

    It momentarily worked after cleaning off the pads, but completely failed after a full reflow.  The lion kingdom has never reflowed a CC1101 without killing it.  The moral of the story is they can't be reflowed.

    The CC1101 got a hot glue blob which has proven a very effective barrier on the raspberry pi zero's.  That operation revealed all the other problems which arise after a few hundred miles.

    Cracking of the chassis continued, so it got a thorough teflon doubler.

    The nylon straps which proved so effective in the past became shredded very quickly.  The decision was made to try expensive Vibram rubber in a conic section.

  • Transporting a DSLR by robot

    lion mclionhead05/20/2020 at 02:26 0 comments

    The lion kingdom last attempted to transport a DSLR in a robot 5 years ago.  It was a failure, especially without frequency domane PID controllers.  Today, DSLR's have shrunk enough that a full frame EOS RP with giant lens finally could be transported in the largest robot & the frequency domane PID controllers make the steering bearable.  It might fit in the smaller robot with enough coersion.  That leaves enough room for a government mandated mask, a shirt, & speaker.

    The power consumption goes to 470mAh/mile.  It could reach 4 miles from the apartment.  The tire wear is a bigger problem with transporting heavier objects.

  • Neural networks, neural networks

    lion mclionhead04/25/2020 at 19:04 0 comments

    Since realizing neural networks were just glorified lookup tables 15 years ago, lions have only lightly reviewed the newer uses. The media doesn't like to talk about the sad truth, but sometimes it leaks through.  The most effective ones today are still trained by humans tagging thousands of photos. The more they change, the more they stay the same.

  • The race for the perfect speaker

    lion mclionhead12/31/2019 at 07:03 0 comments

    The lion kingdom had run with a dedicated speaker battery for years, having never found an affordable DC-DC converter which could power them reliably. They would all disconnect after a short time.  These speakers could all run on a common USB cable & charger, but taking out the battery & giving them 4.2V through the battery leads made them so much lighter.   It was only after accidentally plugging an Auvio into 12V & blowing it up did the solution reveal itself.

    Fortunately, it only blew up the amplifier chip, a HT6871.  The radio & leds were still intact.  It would take 1 month to order a new amplifier from China, so went ahead & got a new speaker.  With this experience, it was decided to put in different connectors for the 12V side than the 4.2V side on the DC-DC converters.  

    The Auvio was such a good speaker during its 3 year lifespan, the lion kingdom pondered putting in a different amplifier chip & finding other uses for it.  The only amplifier chips sold outside China are obsolete class B chips from 1980 which cost more than a new speaker.

     There was also swapping an amplifier chip from another bluetooth speaker.

    It turned out the amplifier from the very 1st speaker, an ANT8110, had the same pinout & worked.  It just had a higher gain.

    While reviewing the datasheets, it became clear that all current speakers had separate amplifier & radio chips.  The amplifiers were all rated for 6V & the radio chips were all using voltage regulators which could take in 12V.  The speakers could run off a cheap 5V USB charger instead of an expensive 4.2V buck converter.  

    2A USB chargers had just become available for $1, so the lion kingdom started using those.  After years of 1A buck converters failing, the 2A USB chargers finally managed to power the speakers.  It was the amperage rather than the ripple or motor noise that made the difference.

    An Anker came in to replace the burned out Auvio & it didn't take long for the lion kingdom to realize it was running hundreds of miles in silence. The Anker was no louder than a phone speaker. There are 2 ways to make a bluetooth speaker louder. The HT8692 amplifier in the Anker has a gain adjustment resistor, but it has a very low maximum gain. Anything below 65k made no difference.

    The next step was putting an op-amp between the ATS2815 radio & amplifier. All it took was a bare LF353 with a gain pot. The Anker provides a virtual ground & dividing resistors to combine the 2 channels.

    The maximum gain of this circuit was limited by the input offset voltage of the op-amp. Above the maximum gain, the DC offset of the output mutes the signal. The lion kingdom tuned it just below the maximum gain & relied on the phone volume to limit distortion. 

    Lions have now gone through 5 speakers, originally directly wired & then bluetooth.  The 1st one was directly wired & arrived in Aug 2016.  Before then, lions spent 6 years running in silence, using painful earplugs meant for humans, or hearing the faint crackle of a phone speaker.

    The 1st speaker used an amplifier from a soundblaster 16 & speakers from a TV.  It needed 12V, but the vehicle it ran in had only 8.4V, so it still needed a spare battery.  It sounded terrible but got the lion through 1.5 years.  The running robot was like a city on wheels, with its speaker.

    The next speaker & 1st bluetooth experience arrived in Jan 2017.  It was too heavy to put in the robot, so its amplifier replaced the soundblaster 16 in the 1st speaker.  It still sounded terrible, but was more convenient.  Here, lions became familiar with the constant dropouts of bluetooth audio.

    In Feb 2017, the Auvio with its future burned out amplifier arrived.  There were finally 2 speakers for lions to have audio at the day job & home.  The home robot was top heavy & couldn't fit much...

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  • Robo Rudulf year 2

    lion mclionhead12/23/2019 at 01:08 0 comments

    The decorations keep getting better, with the discovery of brown pipe cleaners at Hobby Lobby & the order of giant red LEDs for the LED animation.

  • Refurbing vehicle 1 & phone holster tweeking

    lion mclionhead11/30/2019 at 05:38 0 comments

    After 6 months, it was time again.  The transmission was dry & just lubed instead of rebuilt.  Other changes were lowering the front suspension to try to shorten the steering pushrods, grinding out access ways to more easily remove the transmission.

    The battery compartment got taller standoffs to make room for puffing.

    The struts got washers to prevent indentation.

    Wheels got aluminum knuckles & the pushrods had to be realigned again.  Some attempts were made to try to improve the steering, but the right wheel needs a custom pushrod to do the job.

    Green & blue were the same alignment.  Orange was toed out.  Yellow was toed in.  There's no way both toing out & in could give lower power usage than the start.  All of them were within the error bounds.  Hopefully, it just means lions are good enough at aligning by eye that they didn't need any pushrod adjustments.  Noticed the uphill direction was more variable because it was going into the wind.

    Electronicals got some hot glue for strain relief.

    Phone got some hot glue to try to stop the scratching.

    With velcro busted, it was time for a magnet wrapped in suede.  Plastic falls apart very quickly & scratches the phone.  The hope is an entire holster made of suede, but it's quite heavier than plastic.

    Notice all the LEDs got the zip tie treatment.  This has worked best for LED mounting.

    The mane concern is the hot glue coming undone.

  • Steering failure

    lion mclionhead10/15/2019 at 05:07 0 comments

    It broke after only 6 months. The only replacement part is the fabled Tamiya Shaft Bag 58347, long out of production. There are aluminum ones in China with a 6 week waiting time.  Lacking any replacement parts, the lion kingdom attempted a teflon repair. The bolt isn't long enough to reach through the teflon. Teflon is softer than the original nylon.

    During this process, it became clear the steering rods could be 1 hole shorter, so the wheels would have to be realigned for the teflon repair & aligned again next year when the China shipment arrived. All this wheel alignment had the lion kingdom searching for a better way. Lions traditionally aligned the wheels by driving a mile, recharging the battery, & measuring the charge. The charge depended on the wheel alignment as well as the battery temperature & how charged it was yesterday.

    The ideal way is to drive a certain distance & record the PWM, but this requires a constant battery voltage. A Rudeng/RIDEN voltage regulator is still the ideal solution for getting a portable, constant voltage. Getting one is another 6 week China shipment.

    It was while searching for a voltage regulator that lion kingdom realized this was what Sparkfun sold, 15 years ago. What did Sparkfun sell nowadays? Dumbed down educational kits for large schools, big ticket items for corporations, & some standard connectors. Their power supply offerings where now the laptop bricks office supply stores sold 20 years ago instead of the bare boards they used to sell.

    Exotic parts for starving college students & programmers are now only available in China. There's no money to be made in exotic parts just for building other things, partly because Chinese aren't allowed to use imported hardware in their own products.

    A Rudung was sacrificed.  The lion kingdom can remember no time when it needed 2 power supplies simultaneously.  They were only used for remembering different settings or having different connectors.  Manely, they were hoping for a future need that never came.

    The new butter surprise created a stable 9V from a 12V battery.  It had a 0.5V dropout.

    Subjectively, the results were more realistic than without a regulated voltage.  There was a steep drop in PWM for the 1st turns, then a leveling off.  Finer precision was still a matter of complete drives & measuring charge.

    The 1st 9.2 mile drive burned 246mAh/mile.  

  • Tire adhesive

    lion mclionhead09/28/2019 at 07:42 0 comments

    Lions run in hotter conditions than they did before. The wheels tend to spin inside the tires. When it's hot, the tires expand & they never move. The 1st attempt was hot gluing the tires on. That failed. The 2nd attempt was rubber cementing them on. The next attempt will be epoxy resin. The ideal adhesive would be tree sap.

    After 34 miles of hard stop & go driving, the rubber cement was still holding.  The motor definitely cogs more when the tires don't slip.

  • Button & switch failures

    lion mclionhead09/02/2019 at 03:08 0 comments

    So the throttle switch failed on, on the 900Mhz vehicle.  The 400Mhz vehicle which was modified had no further problems.  The stronger pullup resistor & lamination of the switch would have to be done to the 900Mhz vehicle.

    The next problem was the steering buttons.  These have to be replaced every year.  They got some life extension through  wrapping in packing tape.  The last wear comes from sweat which manages to get around the packing tape, holes in the packing tape, & the amount of abuse.  They's constantly banged for minor steering adjustments.  Eventually, getting good contact requires pressing the buttons sideways.  Later on, they lose their springiness.  

    Attempts to make the steering buttons more tactile involved making the center buttons closer together.  This provided clues as to what buttons were in the center., but it meant they couldn't be pressed sideways.  A new idea is to space all the buttons enough to press them sideways, while grinding the buttons at different angles to indicate which button they are.  

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