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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 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 which lions could provide semi autonomous control from.  Proportional steering & throttle would be nice, but weight & durability dictated binary tact buttons.  China simply never made a durable, compact, proportional sensor.

In May 2014 came the 1st controller which lasted a reasonably long time.

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.

Attempts to make it self driving continued through 2015.  Attempts to go beyond pacing & make it carry stuff began in Dec 2015.

This was the shift from a toy to a practical logistical solution.  It was also the moment lions realized it's better to have a semi autonomous solution that works than to perpetually search for self driving while having nothing useful.

The final lunchbox system had 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    https://www.amazon.com/gp/slredirect/picassoRedirect.html/ref=pa_sp_atf_aps_sr_pg1_1?ie=UTF8&adId=A07934293L95IQDPPTPD4&url=https%3A%2F%2Fwww.amazon.com%2FTamiya-Lunchbox-Precision-Bearing-Rubber%2Fdp%2FB00V1QZ86S%2Fref%3Dsr_1_1_sspa%3Fie%3DUTF8%26qid%3D1549922090%26sr%3D8-1-spons%26keywords%3Dtamiya%2Blunchbox%2Bparts%26psc%3D1&qualifier=1549922089&id=4383766425134616&widgetName=sp_atf    10.48

Lunchbox kit    https://www.amazon.com/Tamiya-TMYTAM58347-1-12-Lunchbox/dp/B000BMVIGW/ref=sr_1_3?ie=UTF8&qid=1549922090&sr=8-3&keywords=tamiya+lunchbox+parts    147.2

motor    https://www.hobbypartz.com/96m276-2848-2400kv-16t.html discontinued

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

bec    https://hobbyking.com/en_us/turnigy-5a-8-40v-sbec-for-lipo.html    6.86

Brushless...

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  • Remote controlled Camera system

    lion mclionhead10/12/2020 at 01:04 0 comments

    The lion kingdom designed a 13:1 gearbox for camera panning, only to encounter exponentially growing complexity when it came to structures to support the gears, enclosing it, making it as compact as possible, & making it printable. It ended up being a 4" wide enclosure. Maybe it could be shrunk by using the highest possible printing quality, allowing the enclosure to be less optimized.

    Gearboxes are a pretty high value item, even more than lion machine interfaces. There is a limit to 3D printing imposed by the amount of work required to design the part. There has to be a huge need for a custom gearbox, but in this case there are much smaller, geared stepper motors which could do the job more efficiently.  The original wishlist only called for a common hobby servo.

    In lieu of a gearbox, it was the world's ugliest overextruded shroud. It needs to slide on inner rails to allow access to the inner fittings.

    When moved over to the latest paw controller, the panning appears to stutter more, but it was also 60fps instead of 24fps.  It might only look smooth because of the gopro stabilization.  


    The motion was so bad without a brushless gimbal feedback loop & the ugly shroud proved so useful, work resumed on a single stage 4:1 gearbox.  The servocity pan/tilt mount uses a large 3.5:1 gear with winch servos to achieve real smooth panning.  The winch servos perform a finite number of rotations before requiring a reset, though.

    Was surprised to find the sharp corners of the paw controller weren't noticeable in the real world.  It could be wrapped in rubber for extra bling, but it would just be heavier.  The paw controller with square corners was much more comfortable than the wooden ones lions used since 2013.




    A new 4:1 gearbox reduced but didn't eliminate the cogging. Most of the last stuttering was caused by a firmware bug, but the mane contribution of the gearbox was increased torque.   This used a lot of horizontal expansion tweeking in Cura to align the pinion gear.  The pinion gear took only 20 minutes to print, so it was the easiest point of alignment.

    This was a horrid enclosure, but it just needs to keep clothing out of the gears. It was manely a study in isogrids.  Isogrids are the key to future plans.  Didn't think a lion would ever be able to replicate the crew dragon isogrid pattern. Didn't even realize it was just an isogrid until starting to model isogrids. Thought it either came from aliens or it was an example of humans evolving into their science fiction notion of aliens.

    There is an amazing amount of engineering involved in printing strong isogrids.  Isogrids really do have structural value in the small scale plastic world.  They must be modeled as a single polygon to get the line segments joined with a contiguous filament.  It took a long time to discover the reason top surfaces are rough is because of a lack of a gap between the top & bottom surfaces.  .4mm of infill is ideal.  A 1mm piece with .2mm of infill is stronger than a solid 1mm piece because the isogrid has a flatter bond & because more material is devoted to the structure instead of ridge artifacts.

    More isogrid test pieces. They can be printed facing the bed without support or infill. There's enough give to get flat tops. Helas, the subdivided isogrid would require support. The lion kingdom would also consider modeling custom supports for the subdivisions. A .6mm subdivision layer & 1.2mm triangle layer with custom supports might work, but require a lot of work to either melt or snip off the supports.

    The final paw controller ended up with an isogrid exterior, clamshell, countersunk screws, temporary screw for retaining the spring, larger joystick.  It was frustratingly large compared to the boosted board.  There were always a few things to improve, but it was beyond the point...

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  • Better lion machine interface

    lion mclionhead10/05/2020 at 17:52 0 comments

    Lions long dreamed of fully proportional steering & throttle.  You can't buy the ergonomic knobs & sticks in game controllers as standalone parts. The mechanicals have to be custom designed. The only standardized parts are hall effect sensors & potentiometers buried inside the controls, which are not ergonomical.  Spring loaded sticks in commercial controllers fell apart when subjected to hours of running.

    3D printing finally allowed some progress.

    The journey began with a spring loaded wheel module for steering. The lion kingdom developed a mechanism with a common pen spring, hall effect sensor, & PLA. It's quite bulky compared to the boosted board, which uses an expanding spring.  A fully waterproof remote control would have to be even bigger still.

    This module revealed it's not possible to jockey a steering wheel & throttle in the boosted board arrangement with 1 paw. Boosted boards use the throttle position as a safety rather than a throttle. They always have the safety down when jockeying the wheel.

    A few more prototypes yielded a modernization of the remote control lions have used for 8 years.  The steering wheel goes straight through, making it ambidextrous.


    To lower the bar, this one would only be used for camera panning.  A later remote control for the vehicles would have 2 spring loaded wheels for throttle & steering, along with 2 speed buttons & a power button.  Reverse would be built into the throttle wheel.

    Making it functional only needed 6 hours for final assembly. It was the lion kingdom's 1st experience with .4mm pin spacing on a home made board. A microscope is definitely required.

    Lions are fans of inductive charging, since connectors do so badly in salt water.  The only exposed contact is the power switch.  

    TODO: need a way to temporarily capture the spring for assembly. Electronicals don't fit. Need to make a thicker enclosure. Need guides for the wires. More room on top for wiring & on the bottom for the antenna. Maybe move the power switch down. This prototype is good enough for end to end testing of a gearbox.


  • Motorized camera mount

    lion mclionhead09/29/2020 at 18:44 0 comments

    After being stalled by the automated tracking for over 8 years, the decision was finally made to make a remote control for panning the camera manually.  3D printing finally enabled the custom bearings.  The remote control has 8 functions.  4 timelapse movements are enabled by holding a button during power on.  4 smooth panning movements are performed by the buttons after power on.  The camera is panned by a brushless gimbal motor.

    It was after laying this out that the lion kingdom realized how much its philosophy changed in the last 20 years. An ARM is seriously overkill for controlling a 3 phase motor & receiving packets from the radio.

    20 years ago, a lion would have used an 8 bit PIC, developed the routines required to generate 3 PWM waveforms in software & receive packets from the radio. It's just so much easier to get that working on an ARM & there are enough spare ARM chips in the apartment, it's no longer worth the trouble. If it was 20 years ago & lions had only PIC's, it would have been done the old way.

    Then, after playing with the spectrum analyzer, it was revealed that the giant loop antennas lions used for the last 11 years are unnecessary. They were seen as a way to use balanced antenna pins without a balun. In reality, a monopole gives good results with just a 16nH inductor shorting the outputs & a 100nH inductor in the 3V supply position. If a loop antenna is used, it doesn't need the 16nH inductor.

    Lions had always based their usage on the balun circuit in the MRF49XA datasheet & never tested the signal strength of different antennas, even with the RSSI functionality built into the radios. They just spread the radios apart on a golf course until they stopped receiving.

    The extra parts for the MRF49XA may have been to match a 50 ohm load. When this part was rebranded later as the SI4421, the new datasheet only showed a loop with no inductors, but lions never saw it. They even left out the 100nH inductor that supposedly chokes the RF from entering the 3V rail. The 100nH would only be needed for transmitting & FCC certification. Not sure where the 16nH came from. The MRF49XA datasheet showed a 22nH.

    Sadly, 3D printing can't form metal so we're still stuck with ugly metal motor mounts.

    Hopefully the last plywood remote control lions ever make. This one proved without a protrusion, lions tend to hold it like a TV remote instead of a gun.

    What allows lions to point guns is thumb pressure. Otherwise, they need another protrusion to grab. The boosted board remote has a thumb wheel to keep it pointed like a gun. Lions have used a pinky protrusion for 7 years to free up their thumbs. It's not the most comfortable.

    With that discovery, the waterproof version is probably going to be as similar to the plywood as possible.


    The remote continued the tradition of 4 steering buttons.  Lions settled on this design 3 years before the boosted board remote became popular & indeed long before there were any electric skateboards.  It's worth reviewing how modern skateboard remotes work with some stills from https://www.youtube.com/watch?v=kXDz

    It uses a single hall effect sensor & 2 magnets for the proportinal speed.

    It has some weather proofing but not enough to withstand years of lion sweat.  Sweat getting through the LED holes would instantly destroy it.  They're designed for high paid executives who can afford a $2000 skateboard, who don't exert themselves.  The key to waterproofing is hall effect sensors.  All buttons could be waterproof if the magnets were small enough, but the size of the magnets limit hall effect sensors to proportional inputs.  The only option for buttons is the rubber dome.

    4 button steering has proven advantageous because it doesn't require thinking.  The real slow trimming that comprises 99% of a lion's run is a lot easier with buttons.  A proportional wheel might be useful for...

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  • 3D printed camera mount

    lion mclionhead09/26/2020 at 07:29 0 comments

    3D printing finally allowed lions to mount the gopro on a carbon fiber rod instead of aluminum angle rod.  It was much more stable & the energy burn was much less.  It only burned 280mAh/mile.    That may be a charging anomaly, but it would be a natural outcome of increased stability.  Helas, the farsteners started coming apart as the lion kingdom figured E6000 would bond to PLA.  E6000 does not bond to PLA.  CA glue seems to work best.

    This would be a really shmick set of carbon fiber farsteners if it was on amazon.com. Lions never were impressed by 3D printed prototypes from startups, but carefully designed & manufactured parts can look really professional. 

    The gopro mount is the mane item limiting progress on the next rover.  It's essential for it to eventually pan & track the lion.  How it's done determines what's in the next remote control.  A panning mount can now be 3D printed, but the tracking part is hard.

    1 option is machine vision.  It entails a haar cascade for detecting all the faces & openface for ranking the faces.  Openface is over 5 years old.  It would require a $100 confuser just dedicated to the 1 task & wiring on the pole to capture video.  The confuser is rated at 10W or at least another 100mAh/mile.

    The other option is finding the direction of the remote control RF signal.  A rotating parabolic antenna might do it.

  • Better robots through 3D printing

    lion mclionhead09/11/2020 at 19:19 0 comments

    It's been an incredibly noisy decade with those tamiya transmissions with spur gears.  An earlier rover used a direct drive power system to reduce the noise.  That proved impractical because of the fragility of the motor bearings & the low torque.  The arrival of a 3D printer opened the door to custom drivetrains & revived the idea of noise reduction.

    1 path to noise reduction is a belt drive.  Electric skateboards perfected the low profile belt drive since the lion kingdom's direct drive rover.  You can now easily get belt & pulley systems.   Mounting it all is what requires custom plastic.  The problem is the belt drive is heavy & still noisy.

    The preferred path is hub motors inside the tires.  Any hub motor can be matched with the right tires by 3D printing.  Skateboard hub motors are now mass produced with heavy duty bearings, but a lighter option is a brushless gimbal motor.  The motor should have sensors to improve the starting torque.

    The mane problem is replacing the drive train requires replacing the steering.  There's not enough of the original lunchbox left to justify the cost of using just the steering.  Lions are limited to PLA by money.  Any noise reduction plan would have to begin by fabricating a new steering section out of PLA.  Steering knuckles would be stock, but pushrods & suspension would be custom.  This would yield a completely custom chassis.

    The chassis being custom could now be enhanced to better serve lion needs.  The tires could be replaced by something longer lasting & lower profile.  The electronicals have to be waterproof.  The battery has to be enclosed.  More storage should be provided below the coroplastic container.  The ship should be made longer.

    Another idea that 3D printing could revive is the robotic dog.  Given unlimited money, there are probably fast enough servos to create a bounding motion.  At minimum, 3D printed gears with high wattage airplane motors & spring systems could probably do the job.  It would be for minimal cargo or just pacing.  There is a use case for something that just paces.

    Even harder than the steering is the need for a waterproof remote control.  Even without rain, the sweat from a lion eventually causes the electronicals to die.  Fully encasing the remote control in ninjaflex would do the job & require a $100 investment.  Another idea is molding silicone in PLA.  The gopro is the model for rubber waterproofing.  Ninjaflex couldn't cover sliding switches.  A way to get waterproof buttons & switches from PLA is ideal.  It doesn't have to be submersible, just deflect rain & sweat.  Rubber O rings could theoretically seal every button.  

    The gopro doesn't give a positive sensation of button presses.  EIther ninjaflex or o rings would require more button travel than tact buttons.  

    There are momentary buttons with more travel than tact buttons, yet a somewhat low profile.

    The sliding switches could be replaced by push button switches.

    https://www.digikey.com/product-detail/en/MHPS2283/679-3532-ND/1795387/?itemSeq=339789471

    https://www.digikey.com/product-detail/en/MHPS2283N/679-4052-ND/1795382/?itemSeq=339789423


    The waterproof cap would make the profile higher.  There's no way around a waterproof controller being chunkier.

    Other wishes:

    Inductive battery charger:

    https://www.digikey.com/product-detail/en/MCP73833-AMI%2fUN/MCP73833-AMI%2fUN-ND/1223157/?itemSeq=339790597

    Motor sensors:

    https://www.digikey.com/en/products/detail/silicon-labs/SI7213-B-00-IV/7323038

    Servo BEC:

    https://www.digikey.com/product-detail/en/OKY-T%2f5-D12P-C/811-3419-1-ND/7313703/?itemSeq=340498523

    Speed buttons adjusting the number of steps above or below the configured speed.  Aural cues for the current speed setting.  Broadcast a continuous code...

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  • Tire coatings, silicone grease

    lion mclionhead07/03/2020 at 18:44 0 comments

    In the face of worn nylon straps, another phase of tire coatings began. Aquarium sealer was the absolute toughest adhesive lions ever saw but had trouble adhering to the tires. Vibram rubber showed similar wear to nylon. There was a trend with nylon where impregnating it with E6000 made it more robust. To save money, later nylon straps weren't impregnated with E6000, which may have made it wear out faster. Using 1" wide straps is definitely better.

    The news last covered the Mars rover tire wear in 2019. After traveling 13 miles, it was much more beat up than lion tires after 100 miles. Lions can get hundreds of miles out of tires by frequently replacing nylon straps, but the idea is to reduce the manetenance.



    Then, it was time to rebuild the transmission.


    The mane interest was applying a new grease to try to reduce the noise & to increase the manetenance interval.  After at least 15 years, lions finally narrowed down the ideal lubrication for plastic gears to silicone grease.  It's not sold in the lubricant sections of any stores.  It doesn't show up in any searches for axle grease.  It's only in searches for plumbing grease.  This is the transparent grease used in plastic toys & plastic servo gears. The key ingredient is Polydimethylsiloxane.

    As usual for grease, the 1st few miles were a lot quieter, followed by a gradual return to the usual noise.  Range wasn't abnormally affected.

    UPDATE:

    Silicone grease eventually became a lot louder than stock & decreased efficiency.  It appears to create an adhesive layer on the gears, rather than help them glide.  This may actually not be the grease in toys or it might be an excessively viscous version.  


    Aquarium sealer on the tires wore down faster than vibram rubber, but it managed to stay stuck to the tires.  Vibram rubber actually did pretty well compared to everything else.  Still need to try kevlar.

  • Yet another carbon fiber attempt & failure

    lion mclionhead07/02/2020 at 04:39 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 mclionhead06/25/2020 at 21:31 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.

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