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mini wheelchair controlled by PIC18F452

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kupikupi

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hi guys, im designing a mini wheelchair controlled by PIC18F452...

this are the requirements:
1. it's a mini wheelchair ... enough to fit a barbie dol
2. the direction of the wheelchair will be remote controlled.
3. the wheelchair has to avoid obstacles by turnining to another direction

so, i actually have a rough idea on how to do it .. but i dont know how correct it is .. this is wat i think ..

i use a joystick to control the direction of the wheelchair using IR telemetry .. the signal from the joystick will be transmitted to the PIC and the PIC send instruciton to move to motor of the wheelchair.

my question is ..
wat kind of motors do i need and how do i make it bi-directional ??
wat does the IR telemetry consist of and how does it work??
i was told that an amplifier is needed for the motor .. why is it ??
the wheelchair avoids obstacles in front of it .. i think by using a sensor ... wat sensors do i use ??

can anyone help me ??
 
yea start to study electronica from the ground up ! all motors r bidirectional just reverse polarity. u need to amplify for the motor in the sense that u will at least need a transistor a power one to control i hope u were not thinking of using a direct output of the pic. automatic obstical advoidance is not going to be easy and what do u want for it to change direction ? then in wich should it go or should it just stop ?
all your requirments and ideas are very vague for something that involves:
1 pic control ie programming
2 remote control
3 translation of the pics signals into power control
4 perhaps a laser detector for the obstical advoidance
5 some luck judging from ur experince and don't get me wrong i havn't the foggiest about pics and remote control so good luck
 
u need to amplify for the motor in the sense that u will at least need a transistor a power one to control i hope u were not thinking of using a direct output of the pic.

well... i was planning to use sonething called L293D to control the motors?(is that called an amplifier?? is it ok ?? a silly question ... how do i choose to motor voltages?? 3V, 6V , 9V, 12V..
 
u may use what ever motor u like it depends on the power u use. to control the motor u will need a power transistor or a relay that will be activated by a trasistor but a transistor should do like a BDX53 but u must determine the power supply and there for the motor u will need
 
wat kind of motors do i need and how do i make it bi-directional ??
you can use DC motors with an H bridge driver circuit in order to drive the motors forward or backward, and use PWM in order to control the speed of the motors.

wat does the IR telemetry consist of and how does it work??
I'm not familiar with Josticks, but in my opinion, use the SONY IR remote control. You can find the source code at Nigel's website http://www.winpicprog.co.uk

i was told that an amplifier is needed for the motor .. why is it ??
You should build the chassis first to know if it's working well with the motors then u decide if u need some kind of amplifications

the wheelchair avoids obstacles in front of it .. i think by using a sensor ... wat sensors do i use ??
well you can go for the ultrasonic sensor (transmitter+receiver). You can find some schematics on the net

good luck
p.s:why u need it 4 barbie? :)
 
kupikupi said:
hi guys, im designing a nini wheelchair controlled by PIC18F452...

this are the requirements:
1. it's a mini wheelchair ... enough to fit a barbie dol
2. the direction of the wheelchair will be remote controlled.
3. the wheelchair has to avoid obstacles by turnining to another direction

so, i actually have a rough idea on how to do it .. but i dont know how correct it is .. this is wat i think ..

i use a joystick to control the direction of the wheelchair using IR telemetry .. the signal from the joystick will be transmitted to the PIC and the PIC send instruciton to move to motor of the wheelchair.

my question is ..
wat kind of motors do i need and how do i make it bi-directional ??
wat does the IR telemetry consist of and how does it work??
i was told that an amplifier is needed for the motor .. why is it ??
the wheelchair avoids obstacles in front of it .. i think by using a sensor ... wat sensors do i use ??

can anyone help me ??

You've got a long road ahead of you.. I commend you for jumping right into the fire (you'll have a few of those before you're done)

My advise is to thoroughly plan your design ahead of time. You wont appreaciate undoing months of work because of an insurmountable problem down the road that could have been designed out intially. Consider things like:

1) Is IR the best way to talk to the controllers? Know that if you have one receiver sensor, when the chair is faced away from you, you will lose the ability to give it a command. Maybe a license-free RF transceiver is better suited.

2) Learn about all the electronics you think you need before you try and use them. Before you commit, you will have changed your mind about alot of it and be glad you did. Read up on motor theory and how they are specified & what it all means so you can properly choose one. Read up on power supplies.

3) Ask lots of questions. If you have an idea, show it to others to get feedback. very often, others have an immediate insight and experiences that can save you lots of time & money down the road. Weeding out ideas quickly is more valuable than you probably can appreciate now.

Good luck!
 
well... i actually have only 4 weeks left to finish this project ... we've got no help at all from the lecturer .. i've been searching high and low for help till i found this forum.. where great ppl like all of u really help me alot .

You should build the chassis first to know if it's working well with the motors then u decide if u need some kind of amplifications
could u explain more?? i don really get it, i think i get the rest of ur suggestion ... i just have to learn more bout it ..

p.s:why u need it 4 barbie?
it's not for barbie actually ... it's just the size of the chair that could fit barbie.. :lol:

Is IR the best way to talk to the controllers? Know that if you have one receiver sensor, when the chair is faced away from you, you will lose the ability to give it a command. Maybe a license-free RF transceiver is better suited.
gosh.. i never thought of that, but that's the requirement of the project... could i put the receiver at all four corners of the chair ?? or maybe i could just control it from behind because if im behind, when the chair turns left, right , move forward or reverse , the receiver would always be facing me... i think i dont have to make turn chair turn so much that the reciver will turn away from me ...
 
gosh.. i never thought of that, but that's the requirement of the project... could i put the receiver at all four corners of the chair ?? or maybe i could just control it from behind because if im behind, when the chair turns left, right , move forward or reverse , the receiver would always be facing me... i think i dont have to make turn chair turn so much that the reciver will turn away from me ...
i just found out something bout the IR transmission: i missed that out

" communications with the robot must be conducted from an IR transmitter mounted on a gantry above the maze"

and since it's a mini wheelchair .. i guess i'll the place the receiver on top of the chair .. is it ok ??
 
kupikupi said:
gosh.. i never thought of that, but that's the requirement of the project... could i put the receiver at all four corners of the chair ?? or maybe i could just control it from behind because if im behind, when the chair turns left, right , move forward or reverse , the receiver would always be facing me... i think i dont have to make turn chair turn so much that the reciver will turn away from me ...
i just found out something bout the IR transmission: i missed that out

" communications with the robot must be conducted from an IR transmitter mounted on a gantry above the maze"

and since it's a mini wheelchair .. i guess i'll the place the receiver on top of the chair .. is it ok ??

Yeah thats fine. Whatever solves your issue. Well with 4 weeks left, I advise you to get something put together right away. Buy everything that you can instead of designing it. You'll be lucky if you can get 3.9 weeks of time debugging to get the thing to work. Buy your IR modules. By a uC that comes with sample code for using them. Save as much time as you can. With a project like this and 4 weeks to do it in, I cant see it being anything better than a HACK job. If it were my project and I had 4 weeks left my schedule would look something like:

2 hours brainstorming time saving approaches. Can you buy the chair? What control modules can you buy? Can you buy an RC race car and strip it down and build a wheelchair around that? Think of all the design time that saves. etc.. etc...

2 days to put together a schematic & diagrams of the whole systems electronics. Designing in pre-existing modules wherever possible.

2 days to work on mechanical design. Figure out motor requirements and power supply. Cobble together the wheelchair itself. Make sure that my motors can move the chair with all the added weight.

3 days writing code non-stop to "rough-in" the most essential & critical functions. I.e. motor control.. forget about collision detection for now etc... immediately give up all the NICE features to have more time writing all the CRITICAL features.. It's gotta start & stop. Its gotta move forward & maybe turn.

THEN

use all remaining time debugging the final system and if there is time, add features back in. There a good chance you'll still be trying to get it to drive right with 0 days left.. no one will enjoy a chair that can avoid obstacles but cant properly turn a corner.
 
Buy your IR modules. By a uC that comes with sample code for using them.

for the uC.. i have already got it done... since i have never used IR b4 i really dont know how i could go about doing it ...wat does an IR module consist of and how does it actually work with the uC?? i think i should be ok with the motor part....
 
use the SONY IR remote control. You can find the source code at Nigel's website http://www.winpicprog.co.uk

u just need an IR receiver and the code is on Nigel's website..you can control ur device by a SONY remote control which is everywhere, or u can build ur own remote (i dont recommend u because of lack of time)..
Good luck
 
ChArLyZzZ said:
use the SONY IR remote control. You can find the source code at Nigel's website http://www.winpicprog.co.uk

u just need an IR receiver and the code is on Nigel's website..you can control ur device by a SONY remote control which is everywhere, or u can build ur own remote (i dont recommend u because of lack of time)..
Good luck

u mean i just need the IR receiver at the PIC to receive transmission form the joystick ? how bout the transmitter? where is it ?? could u give me more detail ?? i dont really understand how the IR works....
 
how bout the motor drivers??? do i need L293D or L298?? i just need toget the motor running 2direction .. that's all...
 
thanx.. but wat about IR.. are there different kinds of IR modules?? which type should i get?? i really need urgent help ... anyone please??
 
Sorry i didnt notice you are using a Joystick
Well you have 2 possibilities:
1- Forget about the Joystick and simply use the SONY remote control, so u will only have to build the receiver and buy the remote
2- You have to build your own Infrared transmitter from the Joystick itself. On Nigels' website, you have to build the Jostick module with its software and an IR module with its software. So you have to come up with a combination of these 2 programs in order to build an IR Joystick transmitter:) (that sounds a good name) and in this case you need 2 microcontrollers (you dont have to use the PIC18 family)

Hope you got the idea
Good luck
 
Nope..the IR Receiver is simply a 38 KHz demodulator that detects only this frequency (which is used by IR remote controls)...But the software on Nigel's website is made only for SONY SIRC remote controls that use PCM modulation
 
I'm now facing problems in programming the PIC .. ist, im really bad in assembly, i learning .. but i dun think i can finish learning it on time .. then my C language is better but still not enough to do programming for PIC.. which one should i continue with ? assembly or C?? the project deadline is in 3 weeks.. ans i'm stuck here... someone please help me...thanx...
 
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