Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
Ultibots / PIC AXE controller - NMO - Vic
We've been hard at work on our ultibots and have come up with a couple of bots.
FLAME BOT (unnamed)
Sentry bot with flamethrower for hiding the tennisball behind.
The plan is to have this working with a car fuel injection pump pushing kero. At this stage it isn't looking like this will be ready on time. Work sucks!!!
All terain bot (unnamed)
We've built a prototype all terain tracked robot. It takes insperation from Team Vertex's tracked bot.
At this stage it's weapon will be a water cannon, it has terible trouble turning and the tracks slip when we try. anyways we'll see how it goes on the weekend. We'll try to get photo's up before end of week.
Last edited by NMO on Sat Sep 16, 2006 7:00 pm; edited 1 time in total
Sun Aug 20, 2006 6:55 pm
NMO Experienced Roboteer
Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
MORE PICAXE STUFF
Mat and I have been working for the last couple of weeks on a picaxe relay controller that is simpler than the PRC. It only uses 3 relays instead of 8 but does loose 1 item of functionality, also at this stage it does not have any weapons control.
The one thing it can't do that the PRC can do is have one motor running forwards while the other runs backwards. however Vincent did have issues of control under these conditions anyway.
We have 2 issues to solve before it will be battle ready.
-1- The direction control realy welded itself after about 2 mins today. 30A DPDT relay with 2 100W scooter motors on it. I think using 2 of the 60A horn relays will fix this
-2- Some radio glitching, we have already placed caps in various parts of the circuit with some success.
Sat Sep 16, 2006 5:34 pm
Knightrous Site Admin
Joined: 15 Jun 2004
Posts: 8511
Location: NSW
The problem with welding the relays is because of the 24v, not because of amperage. Andrew can tell you how he fixed teh same problem in Sproing with just a capacitor wired onto it _________________ https://www.halfdonethings.com/
Sat Sep 16, 2006 6:09 pm
NMO Experienced Roboteer
Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
Maybe, it is a 24volt 30amp relay.
Sat Sep 16, 2006 6:28 pm
NMO Experienced Roboteer
Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
I just realised there's a problem in my schmatic with the way the motors are wired to the relays. the basic idea still works but this is the issue when you draw the scematic after you build the design
Sat Sep 16, 2006 8:28 pm
NMO Experienced Roboteer
Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
ok welded relay problem seams to have been fixed. and since I used many capacitors to fix it some of the radio glitches seam to have stopped as well.
The next step will be to play with the code a bit to improve things.
Mon Sep 18, 2006 7:52 pm
NMO Experienced Roboteer
Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
Here is a photo of the controller. it's working pritty well at the moment, with no real issues
Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
Here is the code
'2 channel robot onoff controller mixed
'by Team NMO
'19-9-2006
'THIS IS AN EXPERIMENTAL CONTROLLER USE AT YOUR OWN RISK
main:
pulsin 4,1,w0 'fb
pulsin 3,1,w1 'lr
if w0 < 90 or w0 > 210 or w1 < 90 or w1 > 210 then failsafe
if w0 > 175 then forwards
if w0 > 125 and w0 < 175 then neutral
if w0 < 125 then reverses
goto main
failsafe:
low 1
low 2
goto main
neutral:
low 1
low 2
goto main
forwards:
low 0
if w1 > 175 then fl
if w1 < 125 then fr
if w1 > 125 and w1 < 175 then fff
goto main
reverses:
high 0
if w1 > 175 then rl
if w1 < 125 then rr
if w1 > 125 and w1 < 175 then rrr
goto main
fl:
high 1
low 2
goto main
fr:
low 1
high 2
goto main
fff:
high 1
high 2
goto main
rl:
high 1
low 2
goto main
rr:
low 1
high 2
goto main
rrr:
high 1
high 2
goto main
Tue Sep 19, 2006 8:42 am
NMO Experienced Roboteer
Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
1. I noticed you have no provision in your code to prevent hysteris (sp?). Hysteris plagued my first controllers and after going back through some old code Ajax showed me, I was able to fix that problem easily. I created 5ms hysteris bands to prevent it.
I used the following definitions:
code:
;-RC Channel Definitions
symbol fail_low = 100 ;1ms - failsafe below here
symbol low_on = 135 ;low activate point
symbol low_off = 140 ;low deactivate point
symbol neutral = 150 ;where motor is off
symbol high_on = 160 ;high deactivate point
symbol high_off = 165 ;high activate point
symbol fail_high = 200 ;2ms - failsafe above here
The 5ms deadband between low activate and deactivate prevents the controller from getting confused. Is there any reason you didn't use any hysteris prevention code?
2. I also noticed you use just > or < for checking your pulses and comparing them to the byte words. Maybe it's just me, since I've done a little bit of computer programming, but usually >= (Greater then or equal to) will help code flow that little bit better in certain applications. I kinda just do it as a rule of thumb.
3. Why the complication of using 2 x SPST relays with 2 x DPDT relays? Why not just use 2 x SPDT relays wired in a H-bridge config for each motor, you'll still have 4 relays, but you'll have independant control of each motor (forward/reverse/braking) and you cannot get a short across the bridge if your controller glitches (It will just make the motors apply braking)
Next time your on MSN, I'll try to catch up with you in regard to some code and that nifty failsafe you seemed to have got working (Mine.... failed )
EDIT:
Just worked out why you've gone to the level of complication with the DPDT and SPST relays.... Only running a single PICAXE 08M for two drive motors and RX channels does make things a bit complicated. I "assumed" (To assume is to make an "ass" of "u" & "me") that you were using an 18X chip. _________________ https://www.halfdonethings.com/
Tue Sep 19, 2006 10:52 am
NMO Experienced Roboteer
Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
Some good points there Aaron,
-1- I haven't used histerisis at this stage purly to keep things simple, but you are right that it could improve things. Also I hadn't thought of it.
-2- <= well I new I had forgotten something, but I'll incorperate that into the next version of software.
-3- Yep 08M chips. I'm trying to build the cheapest controlers I can and the 18x would increase the costs by $16.80 using the pcb's from Microzed (I hate vero board with a passion so use it as little as possible.)
Thank's for the feedback. Much appreciated. Many minds make light work.
The cost so far is around $80 and half of that is relays.
Tue Sep 19, 2006 7:41 pm
Knightrous Site Admin
Joined: 15 Jun 2004
Posts: 8511
Location: NSW
lol. I have designed all my designs to run on 08M's simply because I'm too cheap skate to buy the 18X programmer
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
For Prototypes, I like "Donut Board" (The one with seperate holes instead of strips) from Jaycar better than Vero. I use single strand teflon wire-wrap wire (Kynar) to do point-to-point wiring rather than cutting Vero tracks all over the place.
The only catch is you need to find a wire-wrap-wire stripper. The look like a little v-notched razor blade. they can be difficult to locate, but once you have one, point-to-point is much easier than vero drilling _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
Tue Sep 19, 2006 9:13 pm
Totaly_Recycled Experienced Roboteer
Joined: 15 Jun 2004
Posts: 1346
I just use the long tail ends off the components lol
Tue Sep 19, 2006 9:53 pm
Grotto
Joined: 30 Aug 2005
Posts: 38
Location: Morisset NSW
I work best similar to spocky using the jaycar donut boards,
but I tend to use telephone / cat5 cable wires instead of
the teflon stuff.
That way I can still have multiple colors to choose from and
from a really cheap source. (dumpster diving )
After all, who doesnt have tonnes of telephone cabling or
dead network cables lying around being used as rope?
( or am I weirder than I thought? )
Also, what 18X programmer are you talking about? What
development tools (software) are you using? I'll edit them in
when I get home, but I use the same set of FREE (legit)
software tools, and a home-built programming cable to
do all versions of the 08 and 18 picaxes. _________________ "The future is not set. There is no fate but what WE make."
........CEO Cyberdyne Systems
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