robotic wheel chair help

Hello Prajwal,  That question is a bit too general I'm afraid. Do you already have a wheel chair? Does it already have motors? Do those motors have drivers (like: boxes that take power and control, to drive the motor)? If  yes, do you know how those work?  If you report that, we could give you some directions on where to start reading next.  Victor

thank you victor for replying.

actually we are building this as our college project.we have thought of using DC motors and 2 axis joystick for conrtolling the directions.actually we don't what device drivers are!! where to use.:(

Hello,

This is your college project; I think it would be wise to first read some information on electronics and on, Arduino. Do some test projects with switches, potmeters and ontrol some LEDs before turning on a robotic wheel chair. 

Good luck in trying things out!

can u pls tell me what value of capacitor must be used for connecting external supply to H bridge for driving 12V dc motor..pls

No one can answer that question sensibly -  the capacitor size depends on the H bridge design, the size of the motor, the precise nature of the power supply, the length of the wires etc etc.

You are way out of your depth here - you need to learn a lot more about circuit design than you seem to know to design your own motor control stuff or alternatively find  a ready made design that does what you want.

There are companies that sell ready made motor controllers with instructions and support but they are not at Arduino type prices.

If you post a circuit (schematic) of your design so far it might be possible to advise about component values. (You need to put all the component values and types that you do know on the diagram and ideally explain how you got there.)

MK

When using PWM to drive H-Bridge type power amplifiers, use 1,000uF per ampere of motor current. For example, if you use a 12V 10A DC motors, each of their H-Bridge supplies should use 10,000uF 25V capacitors, connected as close as possible to the H-Bridge.

Rajiv,

It's good to have some rough estimates, but can you give a bit of background on this estimation? Do you know where this figure (10,000uF) comes from? Also, can you give a guideline for the ripple current needed in these capacitors?

Victor, I design and build DC servo drives. The figure of 1000uF per Ampere is derived from years of practice across over a thousand servo drives... Do remember, the capacitor is to be placed at the input to the H-Bridge, never at the output...

OK, cool. Just wondered whether there's a theoretical background for your experience. Not that I don't trust you, more that I'd like to know whether I could have done some back-of-the-napkin calculation to get to the same result.

Victor, you might want to read this article... http://sound.westhost.com/power-supplies.htm

A reading of theoretical articles / experimental results, coupled with practice, allowed us to reach a thumb-rule we apply successfully to our drives.

can u pls tell me how analog joystick works  and also help how to call interrupt depending on joystick..pls

can u tell me how to check the extream values of the joystick(left right top bottom) in serial port using arduino ide....

can u tell me how to check the extream values of the joystick(left right top bottom) in serial port using arduino ide....

Look up how to read a potentiometer via the analog port. A joystick has two potentiometers - one for X and the other for Y axis. The Arduino's 10-bit ADC will give you 0-1023 values between 0V and Aref (usually 5V). Obviously, whatever maximum and minimum values you get for X and Y axes, the centre-point of the joystick will be approximately at the middle of the two extrema. To get a feedback of the two extrema and the centre-point value, read the values and print them to the serial monitor with a serial.print command. Please look up how to use that... make use of the copious examples accompanying the IDE...

dear sir

               i have almost completed the code. I need u to check it once. if u provide me your email id I will send the code and the circuit diagrams so that u can check it.

You're welcome to send me the code, Prajwal. I'll comment in your code and send it back to you. But I hope you're keeping Alan Wood's advice in mind...

Send mail to rajiv.tctech AT gmail.com

ofcourse sir I learnt a lot with my project... thank you all...