Awful Gaudy project

[beomagi]

My goal isn't a comp crawler, or a crawler that adheres to the rules of what a current crawler should be using - I'm not going to be light, and I know my motor choice wont be best. I'm out for basic crawling capability and fun. Maybe I'll optimize a bit more later. I've learned a lot from this forum, so I know I'm heading in a direction most wont.

I doubt I can shave axles like many here do. If I try it, i'm sure I'd destroy something.

Most of the parts I'm using on this project are from clearance, or heavily discounted ebay sales.

This started as an open diff rock racer, and halfway through i changed my mind.


I originally picked up ax10 axles to make a "buggy".

And I really liked how it turned out. Sure my c-o-g was higher than a comparable RC, but this was mine - I sourced parts, figured out my mounting choices, made links - this was exhilarating. You guys remember your first build? Awesome right?!

So I had to make another.
PC295901

OK so that last one has undergone transformations with the shock and battery mounting constantly. I think I just need bigger wheels. Stepping over stuff is fun.


Anyhoo, sometimes when I see a deal - something on clearance, I go for it. After breaking the axle housings a couple of times (my first buggy) I realized the AX10 housings are ok for load, but bad for impact at speed. So I've been using aluminum housings (rc4wd housings on the first, golden horizon on the second).

A couple years ago I saw a deal on some ugly looking green anodized golden horizon axles, STRC 4 link plates, blue knuckles, lime green chubs and a Fast Lane RC 55mm SPV chassis.

A couple months ago I started getting interested in getting all my RCs working again, and saw these parts in a box. I decided well... why not.

So I layed out some available parts

P6235798
P6235796

Now you can see why i'm calling it "Gaudy"...
The different green shades clash, blue kills any uniformity.

A few weeks ago I thought to myself halfway to making this roller - I htink I should make a crawler instead. I have enough go-fast fun-vees. Ever change your mind way into a project? yup!

Changes: Diffs, motor, spur. I went from 14:36 open diffs, to 13:43 locked.
Holy crap it's annoying to get at AX10 diffs when you've got servos mounted and all.
The velineon went and in came a generic $20 1650kv brushless motor. I know - i know - it's better to to brushed. But I already had a $30 brushless ESC (hobbypower - a hobbywing clone - i.e. same esc as hpi flux v2) so this was cheap. Plus I kinda like the idea of not worrying about brushes. I saw spare few reviews on these motors, so I'm taking a chance. I've seen other people spend more on lotto, so this is probably a better deal.


Shafts are junfac I think it was from rc-recycler? $20 for a pair. Looked like it was never used. i've destroyed a few plastic ones, so my other ax10s are using MIPs - but I'm trying to be cheap here, and read decent review on the junfac.


On my faster builds, I use 32 pitch NTC3 spurs, so I'm jumping from a 56 tooth spur to 87. Pinion is down from 18 teeth to 14.


Up next links, shocks, electronics.


This is also going to be my first 4 wheel steer vehicle. I know digs are more capable from watching videos, but I'm not looking at competing in anything.

Couple more pics, since I'm REALLY BORED in-between waiting for different packages to come in... Waiting for some Solar servos to replace the MG996rs I've been playing with.
P7075927
P7115931

Found some old mini-t shock spring replacements from when I was a Mini-guy. those fit nicely on the Maxx shocks for a more narrow profile.

Something about the chassis I don't really like though. It needs some curves...

 

[Master Basher]

looks very pretty, but I would definitely ditch the aluminum axle housings and do the xr mod to the front and use xr shafts or better for steering. Those stock set ups that you are running will be frustrating if you ever plan on playing with other folks on the rocks at any type of comp.

Nice chassis adjustment capability though.

 

[beomagi]

Looked up the xr mod you spoke of.
http://www.rccrawler.com/forum/axial-ax-10-scorpion/385197-xr10-mod-ax10-axles-parts-list.html
http://www.rccrawler.com/forum/axial-scx-10/387262-how-do-narrow-xr10-mod-axial-axles-2.html

The beef tube thing looks like some work, though it's doable. Second post I can get into. In the future, my next crawler will use a dig, and I'll be going for more steering then. It's nice to know there's a name to the mod. Thanks.

No comp machine here. I'm going with 4WS/crabwalk - though the Bastens QuadSteer module I received today seemed to gimp any servo connected to it. I went through a box of spares using the Bastens QuadSteer, servo power, speed and smoothness drops. Under load, it moves with a stutter. At neutral, I can move the arm fairly easily. Without BQS servo is awesome. This is with me hooking servo power directly to the battery, so BQS signal seems faulty.

 

[jason1973]

you need a BEC to make sure your voltage doesnt drop in your servos when you switch to crab. 2 servos require more volts when being used at the same time.

search the forums too. i am sure i saw something about 4ws and crab walk in the super forum.

 

[beomagi]

I'm testing before adding to the crawler. This it's direct to battery.

 

[beomagi]

I've been going back and forth with Bastens support. It feels like i'm not being taken seriously. It's pretty much down to me taking a video to show them it's not working like it should (great way to keep clients... </sarcasm>).

Basically, I'm showing the difference between using the BQS (Bastens Quad Steer) and not - It's a single servo driven by a servo tester on oscillate. The load is a simple shock absorber.

Will update with video as soon as it's uploaded.

EDIT:

Video: https://drive.google.com/file/d/0Byn3RaVwsVuvTER3NEhpOEx4Vjg/edit?usp=sharing

 

[beomagi]

I wasn't liking the width of the body. Not at the front and rear - even without xr steering mods, large wheels would rub the shocks at lock.

So I used my vise and bent the front and rear inwards.

P8136665 by be0magi, on Flickr

Also finished getting around to my shock setup.
P8136666 by be0magi, on Flickr


Front:
P8136667 by be0magi, on Flickr
Rear:
P8136668 by be0magi, on Flickr

Losi 5mm Rod ends, brass sleeved all round.
P8136670 by be0magi, on Flickr


Enough room up front and rear for all my electronics - though I'm hoping to give the 18650 cells I picked up a proper shakedown. Not much space needed, and it should deliver 7.4 volts, 2600mAh with 30Amps continuous drain (on paper). Since as a crawler it shouldn't really draw that much I'm hoping it works out well.
P8136672 by be0magi, on Flickr

 

[Postclanker]

Interesting build....don't think I've ever seen a Losi mini spring in yellow (at least it looks yellow, hard to tell with all the other clashing colors :mrgreen. Was wondering where the tension sits in relationship to say an orange (stiff) or a green Mini-t rear spring....soft, medium, hard??? What is it?

Now I'm going to watch your video...

 

[Postclanker]

Try hooking up a BEC and see if that helps your steering....

 

[beomagi]

Pretty much the same with a CC 10amp BEC and bigger pack. Not much more power than the eneloops.

So I'm playing around with the BEC today not paying enough attention (my 3 yr old fell and had a booboo) hear a snap, pop, and smell burning... Yup, I put the BEC in wrong on my bandit's pack...
Weird though - the green light comes on, but there's almost no power available.

Ah well. Least I got my shocks and links bolted up. Missing 4 5x11x4 bearings, and fuel line I was using for spacers. I think gnomes hid em.

 

[beomagi]

Getting some good feedback from Bastens now. He also did a video, though with no load on the servo, but he's sending another Bastens Quad Steer over (that's class). We're suspecting a defective module.

I'm probably going to kick myself for this, but I tend to get into niche area of a hobby and spend a lot of effort there. I ended up picking up a mini oscilloscope that can output to CSV file (yay for easy scripting!) and an arduino nano to experiment with my own servo driver.
Never played around with arduino, so this should be fun

The gnomes apparently returned my fuel line, and some ax10 CVDs (or my eyes are just that bad). The stub axles in my first buggy are soo badly mangled, it's like a permanent drag brake.

 

[beomagi]

Got the Oscilloscope. Toyed with it for 5 minutes, but the signal shown explained the problem. It seems my Bastens module only sends every other pulse. Instead of a pulse every 20ms, it's sending one every 40ms, so the servo is getting a signal then interprets the lack of a pulse as no signal repeatedly, hence the lack of power and stuttering. I'll post pics and how to test later tomorrow.

 

[beomagi]

Here's a test with the Oscilloscope.
https://docs.google.com/file/d/0Byn3RaVwsVuvTE92WkhhcjRPVkE/

I'm hoping the one being sent will correct the issue. could be a bad clock, or if these are programmed pic controllers, a typo.

EDIT:
I've been able to have some success with the arduino nano to read servo positions on 2 pins.

Calculating the rear steer signal from this should be simple.
i.e. since I'm using a variable 3rd channel, when max, output signal=input signal (i.e. crabwalk). When the 3rd channel is at minimum, output signal is reversed (i.e. 4WS).

here's the code so far for reading 2 pin signals. The extremely basic mode algorithm will be extended a little to help keep glitching down.

volatile unsigned long leadingedge1;
volatile unsigned long leadingedge2;
volatile int pulsetime1; 
volatile int pulsetime2;

int ch1_1=1500;
int ch1_2=1500;
int ch1_3=1500;

int ch2_1=1500;
int ch2_2=1500;
int ch2_3=1500;

int servoin1 = 2; // pin 2
int servoin2 = 3; // pin 3

int servoout1 = 7;   // pin 7
int val = 0;     // variable to store the read value

void setup()
{
  pinMode(servoin1, INPUT);      // sets the digital pin 13 as output
  pinMode(servoout1, OUTPUT);      // sets the digital pin 7 as input
  leadingedge1 = 0;
  leadingedge2 = 0;
  pulsetime1 = 0;
  pulsetime2 = 0;
  attachInterrupt(0, chan1in1, CHANGE);
  attachInterrupt(1, chan1in2, CHANGE);
  Serial.begin(115200);
}

int mmode(int a,int b,int c){
  int d=(a+b+c)/3;
  if (b == c){
    d=b;
  }
  if (a == b){
    d=a;
  }
  if (a == c){
    d=a;
  }
  return d;
}

void chan1in1()
{
  if(digitalRead(servoin1) == HIGH)
  {
    leadingedge1 = micros();
  }
  else
  {
    if(leadingedge1 > 0)
    {
      pulsetime1 = ((volatile int)micros() - leadingedge1);
      if (pulsetime1>0){
        leadingedge1 = 0;
        ch1_3=ch1_2;
        ch1_2=ch1_1;
        ch1_1=pulsetime1;
        pulsetime1=mmode(ch1_1,ch1_2,ch1_3);
      }
    }
  }
}
void chan1in2()
{
  if(digitalRead(servoin2) == HIGH)
  {
    leadingedge2 = micros();
  }
  else
  {
    if(leadingedge2 > 0)
    {
      pulsetime2 = ((volatile int)micros() - leadingedge2);
      if (pulsetime2>0){
        leadingedge2 = 0;
        ch2_3=ch2_2;
        ch2_2=ch2_1;
        ch2_1=pulsetime2;
        pulsetime1=mmode(ch1_2,ch2_2,ch1_2);
      }
    }
  }
}
void loop()
{
  Serial.print(pulsetime1);
  Serial.print("--");
  Serial.println(pulsetime2);
  delay(20);
}

 

[beomagi]

Fun Weekend Shot a video of the oscilloscope test to BQS designer, so hope this helps figure out what the issue was. Hopefully it's a one off.

Because i'm without a working module for a while I tried my hand at arduino programming and am almost there - arduino nano boards are cheap <$12 easily online.

Figure I can use this for the next vehicle in my queue (bully). The mechanism I'm working on is to use the variable 3rd channel of my rc3s controller to smoothly transition from 4ws to crabwalk. It's essentially a signal multiplier if we were to map RC signals from -1 to 1.

P8246696 by BE0MAGI, on Flickr

 

[beomagi]

Woo - Heard back from the Bastens engineer.

I looked into the bug you brought to my attention. I see that that is exactly the cause of the issues you are having, kudos to you!! The funny thing is my servos (an my 20 or so other customers servos) don't have problems with this 40ms signal span. But to be 100% compatible I need to fix the code to have a 20ms span.

Based on my own testing, this seems to affect digital servos more than my analog servos - I don't have many analog servos, so could be just that couple that are less impacted.

He's sending a third module over - once tested, I'll run it though the scope and arduino to analyze the signal and post here how it's looking.

The interesting part :

P.S. are you interested in testing my winch control. I sell a separate module that controls a winch (seen on my website here Bastens Winch Control module works with either 2Ch or 3Ch transmitters ) but I can offer you a custom module that will control both functions of four wheel steering AND winch control … that is if you are interest.

So I may have the luck to test another module we'll see how it goes.

 

[beomagi]

Had major problems getting wheels on of all things....

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Most my hex hubs (not axial) didn't fit. Then my beadlocks - Gmade beadlock rims were in too far and rubbing on the knuckle's steering arm.

I ended up using some gmade 12mm hex hubs which offset the wheel 19mm - I think that's 12mm more than normal? it's a little wider than I wanted probably not too bad.

Of course I didn't have the right pins either (why not come in the packet with hex hubs?) so I ended up grinding down some other brand's pins to fit.

ლ(ಠ益ಠ)ლ

Still think I like how it's coming out. Kinda splitting time between finishing this and tinkering with the arduino. I think I now have a firm handle on processing RC signals and handling output. I'll probably wind up using my own 4ws solution, but I now have plans for the bully - namely I can use the arduino board to make my own "dig" unit cheaply there.

Also thinking I can use my 4th position switch to move about a camera mount when held, and drive the car when it's released. No clue what I'm doing about packaging it, since it's still on the breadboard, but I'll handle that when I need to.

 

[beomagi]

I guess It's a good thing I used the junfac 19mm width hex, because I finished getting on all the wheels. Worst case scenario for rub on shocks is turning at max articulation, where even with the slightly enhanced width and mini springs, the large masher tires still rub a little.


P8316759 by BE0MAGI, on Flickr

P8316758 by BE0MAGI, on Flickr

P8316757 by BE0MAGI, on Flickr

P8316762 by BE0MAGI, on Flickr



So I'm STILL waiting on my replacement Quad Steer. However I think I've figured out how to do it myself, and after much testing, logging output figures, hooking up and oscilloscope etc, I'm pretty sure of the results. It seems depending on when you send data to a servo you can interrupt other processes - like reading.

So I ended up using a short loop that only triggers if I've seen an end to the pulse from channel 1, then turns the triggering check off. The pulse comes in again, and end pulse turns trigger back on etc. This seems to keep the timing well enough to keep my pulses without any noise.

P8316765b by BE0MAGI, 4WS/CrabWalk smooth transition switch

My version doesn't use a third channel like a switch, instead it smoothly transitions from the rear signal being equal to the input signal, to the rear signal being the inverse of the input signal. So this is acting as what I'm calling a signal multiplier, if we map the input signal from -1 to 1.

to expand

where 1/0/-1 indicates servo direction, 0 being neutral.

chan1 │ chan3 │ output
──────┼───────┼───────
  1   │   -1  │   -1
  1   │    0  │    0
  1   │    1  │    1
──────┼───────┼───────
 -1   │   -1  │    1
 -1   │    0  │    0
 -1   │    1  │   -1
──────┼───────┼───────
  0   │    *  │    0

I'll post the code later. It's pretty final.
Figure I'll leave the board as is. It's easy to make changes this way and swap out a board if I have a need to. I have other plans - though shipping from china takes a while, I now intend to add to this project a more electronic slant - current/voltage datalogging, possibly angle warnings and readouts.

 

[beomagi]

I received a package from Bastens yesterday evening and got a chance to check out the new Quad Steer Module (Bastens QuadSteer 4 wheel steering control module works with either 2Ch or 3Ch transmitters)

The new version works great, so if you're after a complete plug and play setup, I can recommend it easily.

The vendor also sent a bunch of stuff for helping out - battery testers and displays, an arduino pro mini, really fun stuff

 

[MattTheGenus]

Dang man, no misleading title here lol.

Easy off oven cleaner eats anodizing like nobodies business, if you ever decide to make it one color.

 

[beomagi]

I have used that method before, though sometimes the finish under the anodized layer can be a little less than uniform (or maybe I left it in too long...).

I'll leave it on till it's scratched off through use



This project is somewhat changing from just making a 4WS crawler off clearance parts to playing around with what I can do with an arduino on a RC platform. Have some LCD panels and other arduino sensors on the way.


For this one I'm thinking of having a display in the top or rear read out pitch and roll angle, with a warning to signal danger points.

I've loads of stuff I'm planning for the next one which would be on bully axles - hoping to see how best I can monitor temperature of components, voltage from battery, current to motors, angle of tilt/g-forces. Have some ideas on monitoring wheel speed/motor speed, and figure i can use the 4th channel to switch from controlling throttle and steering to moving a servo mounted camera.

Wondering what else makes sense to monitor or control using the arduino.