new robot project

[aladdin83]

hi all,

i got this old project from my advisor

its an electric cart

it has two dc motors, each has its own driver circuit on the back

they are connected to an analog circuit and a joystick

i replaced the analog circuit with a PIC16F877A ucontroller IC

and I kept the joystick and used it to send signal to the uC

anyway, now I have to find a speed sensor that I can use to measure the speed and display it on LCD

any ideas for the sensor?
I cant use a hall effect sensor cause i have no place to fit it on the project!

 

[Nigel Goodwin]

You just need a sensor to detect the wheel rotation, hall effect, reed relay, IR beam (either broken or reflected) - there are loads of different methods.

 

[aladdin83]

how is the IR sensor work?
do I point it at the wheels and it detects motion?
what is making the task a bit difficult is that I cant attach anything to the wheels and also the cart will be used outdoors, so, dert getting on the wheels has to be taken into concederation

 

[Nigel Goodwin]

Any optical system has to be kept clean.

 

[dknguyen]

how is the IR sensor work?
do I point it at the wheels and it detects motion?
what is making the task a bit difficult is that I cant attach anything to the wheels and also the cart will be used outdoors, so, dert getting on the wheels has to be taken into concederation

A magnetic and a hall sensor would be more rugged in that case.

 

[aladdin83]

A magnetic and a hall sensor would be more rugged in that case.

i am using rubber tires and i cant stick magnets on them !!

i will try to figure out a way for it to work

thanks for the help, appreciate it!

 

[Nigel Goodwin]

What about the wheels - tyres are only part of it.

 

[junior000]

hi,
you can calculate the speed using normal ir sensors(and the method is very economical and cheap)

step 1>build an ir sensor
step 2>make sure your wheel has 4 holes in them
step 3>on one side of the wheel make sure you keep ir sensor aligned to the holes and on the other side a white sheet so that a signal a can be sent back to the ir when a hole is detected.

so one rotation the ir sensor goes high 4 times.

if the sensor goes high for 32 times,the number of rotations are 8 (32/4)

regards.

my first bot