some advice on a new project

barneydog

Member
Hi all, its been a very long time.

not done any projects for a few years and am now getting back into it as have come up with a plan I would like to achieve!

I have decided to build a RC bus from scratch. (god help me)

I'm breaking all the circuits required down into separate ones before joining them altogether and make then fully remote control, and with the option of flicking a switch and some of the systems turn automatic depending on where the bus is at that current point.


Display board. Displaying destinations and also numbers on the right as you face it. Is it possible to get the OLED to use 3/4 of the display as two lines and then the last 1/4 to be large numbers? if not, just large letters and numbers using both lines.

a couple of the circuits will be operated by servo such as doors opening and the bus kneeling. which could be directly done by rc control, but my thinking is I want to be able to have a separate control, made from picaxe. Lets say for now it has up, down, left, right arrows, and two additional button. Left opens doors, right closes doors, up changes display to a higher number messaged, down to a lower number message. and the additional buttons makes it lower and raise. is this all do able with picaxe and limited electronics experience or am I starting to really punch above everything?

lastly what i would like to achieve is the remote has a switch, if its off, doors and kneeling is manually done via remote, flick the switch on and it does the following

shuts off remote buttons, and makes it all automatic.

have some bus stops made they will have for example IR built in and the bus has some built in, when it pulls up they send the information to the bus to open doors and kneel. certain bus stops will send new destination codes, so it will change the display. after a delay of 3 seconds it automatically closes doors raises.

trying to give it the manual touch, but if set out say 5 to 10 bus stops in a loop, it can travel along and automatically update and operate as you get to the stops in turn.

many thanks in advance for any advice given.
 

nick12ab

Senior Member
Display board. Displaying destinations and also numbers on the right as you face it. Is it possible to get the OLED to use 3/4 of the display as two lines and then the last 1/4 to be large numbers? if not, just large letters and numbers using both lines.
Yes, but the character OLED will have a one pixel wide gap between each 5x8 character block.

The eight character spaces can be assigned the eight CGRAM characters, then the CGRAM can be changed by the PICAXE to display the appropriate number.

If the gaps are unacceptable, you will have to buy a graphic OLED instead.
 
You might consider using shape memory-wire (muscle wire) instead of servos for the doors. I have seen these being used on N-gauge rolling stock to slide doors open and shut.

The IR idea sounds interesting, although it is not clear whether your proposed bus drives itself automatically or is driven manually from stop to stop.

Ian
 

goom

Senior Member
Perhaps a programmable multi channel (9 channel?) hobby RC transmitter/receiver could be used as the core of your set-up. Check out HobbyKing for some inexpensive examples. You can always use PICAXES to intercept the output from the receiver (using PULSIN) and take the values to direct appropriate logic, and send signals to such devices as servos, muscle wire, displays etc.
 

barneydog

Member
thank you for your replies. Your responses have been considered, but when writing the initial post, I suppose I took it for granted that you would already know those answers as I did lol.

thank you nick, I will read into the displays as everything you have said seems to me it would be very acceptable, will just need to check the screen sizes and the size of the hole its going to have to fit into.

Ian, I did look into the wire, but felt left with to many questions. This will be much larger than N gauge would it have the strength and how long does it normally last for? I will read any info picaxe shop has on it, as I'm sure its for sale there. The IR system would purely be for the doors, kneeling, and display to be automated not the driving. But after seeing the proximity sensors, they could be another interesting project for the future lol.

Goom, this I have already done will attach the youtube channel of previous pic projects surrounding model trucks and the layouts they use. I could make a RC switch that could open doors, then after a 0.5 sec delay lower the bus. wait an additional X second time delay then raise it close doors. This would tie up only one channel as the all the lighting, hazards took 3 channels.

You all have given me many things to think about and I now need to get planning on a paper basis and get things set on how i plan for it to work. I will keep posting as I progress to get feedback, advice, and never know may help someone else out whos wanting to achieve something similar.

youtube chanhttps://www.youtube.com/user/barneyhounddog

tamiya truck lights is the one using all the channels
 
Nitinol

Ian, I did look into the wire, but felt left with to many questions. This will be much larger than N gauge would it have the strength and how long does it normally last for? I will read any info picaxe shop has on it, as I'm sure its for sale there.
I think in terms of mechanical strength Nitinol is similar to mild steel wire so, correctly suspended, it can exert a fair old pull. Not sure about fatigue life: basically it has a low and a high temperature form, and it will try and recover its original shape when heated. (The "original shape" can be set by soaking at ~500C - apparently a small blowtorch will suffice, should you not have a muffle furnace handy).

(EDIT: doing a little digging, Nitinol is capable of accomodating far greater elastic strains than other metal alloys, but the fatigue properties seem to be still a matter of discussion)

One of the more interesting applications I have seen for it was a tiny P51 Mustang radio-controlled plane, where the control surfaces were all controlled by Nitinol springs.

When I worked in St. Leonards I did a few drawings for a Nitinol actuator for automating an industrial process: it was after I handed in my notice so I didn't discuss it with anyone. When I have the current (pardon the terrible pun) projects out of the way I might revisit the project: I am rather interested in using an IMU to sense robot arm position.

Ian
 
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Out of interest, are you looking at scratchbuilding the bus itself, or building from a kit? It's a while since I bought anything r/c which wasn't an aeroplane :) but radio-controlled buses seem to be thin on the ground.

Ian
 

barneydog

Member
Its all going to be scratch built, I drive buses so have complete access to everything on the one I plan to build. One week into planning now, and the old A4 pad is starting to fill up lol.

Only two parts which are becoming really difficult, is the OLED display, I can't get head around how to do the letters and numbers at different sizes, is there a sample code doing that I could read and get the basics of how to do it. Never used displays before! Have started to wonder if it might be worth have the display on rollers like the bus would have had, and motors drive it by using the sticks. be more authentic lol

Other part is scales! I never knew how complicated they could be.

The bus will be a Dennis Dart, more than likely the 10.7M one better referred to as a super dart. Drive them on a regular basis and they are much better than newer buses Dennis Dart
 

nick12ab

Senior Member
Only two parts which are becoming really difficult, is the OLED display, I can't get head around how to do the letters and numbers at different sizes, is there a sample code doing that I could read and get the basics of how to do it. Never used displays before! Have started to wonder if it might be worth have the display on rollers like the bus would have had, and motors drive it by using the sticks. be more authentic lol
Have you gone for a character or graphic OLED?
 

barneydog

Member
was thinking of AXE133Y, as it seemed to be the smallest and i dont think there is going to be huge amounts of space for a chunky board.
 

nick12ab

Senior Member
was thinking of AXE133Y, as it seemed to be the smallest and i dont think there is going to be huge amounts of space for a chunky board.
If you use a larger PICAXE as your main PICAXE you can control the OLED directly without using the AXE133's add-on board. You would have to do it that way if using a graphic OLED because the PICAXE-18M2 isn't fast enough to draw each small character between serial bytes.

If you were originally going to reprogram the PICAXE-18M2 and use it as your main PICAXE (on the AXE133 PCB) then either OLD will be fine.

But I would focus on the servos etc. first as they are more important to the operation of the bus.
 

barneydog

Member
servos are going to be receiver controlled and not picaxe controlled. I will upload a picture of the desired electronic set, which will be open for suggestions and change at any point.
 
was thinking of AXE133Y, as it seemed to be the smallest and i dont think there is going to be huge amounts of space for a chunky board.
That display has its own PICAXE chip included which drives the display - you send it serial data from another PICAXE. As it stands you cannot alter the size of the lettering, although if you alter the programming of the PICAXE it might be possible to. The code itself is open source :).

Ian
 
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