Electronics > Electronics

hi... i got a question

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annoyin_kid:
hi there im new to these forums and i wanted to know some more about a robot that was on this site. the servos on stampy the sumo robot are they modded so they are one of those 360 degree turn servos? and wouldn't a motor on its own also be able to do the same job as the servo or was the servos used because they can turn foreward and backward without the h-bridge?

Admin:

--- Quote ---the servos on stampy the sumo robot are they modded so they are one of those 360 degree turn servos?
--- End quote ---
yeap, they are modded for continuous rotation


--- Quote ---wouldn't a motor on its own also be able to do the same job as the servo or was the servos used because they can turn foreward and backward without the h-bridge
--- End quote ---
motors will work too, and could probably go faster. however my limitation on speed was determined by how fast the scanner could get a reliable lock on a target, and servos made that easier to do.

but i also had two other limitations:
- i wanted to build the robot with as little effort as possible, and servos are reliable prepackaged solutions. i own wired up motor drivers, too, but i didnt want to bother figuring out PID control or using encoders. as a result, that robot took me only 25 hours to make . . . ~10 hours of it correcting dumb mistakes . . . ;D

- i already owned the high speed servos, giving me a strong preference over buying something else

annoyin_kid:
how much torque are those servos and what kind are they? what kind of rpm are you getting from the servos and what kind of motors would you use if you did and what are its specs?

i live down in new zealand and the parts avaliable here are quite limited so i gotta look around for ages to find a shop that sells the stuff i am after and the more specs i get about the stuff i need the easier it is to find something close to it.

also what do you mean by 'PID control' and 'encoders'? im new to electronics and i only learnt basic electronics last year at school and i only know how to use picaxe microcontrollers.

ps. nice job you did with this website and thanks for making it, it really is useful for beginers like me ;D ;D ;D

Steve Joblin:
Servos (modified so that they rotate continuously) have been used in small amature robotics for several reasons:

1.  they are relatively inexpensive
2.  they are easy to mount
3.  their internal gears create good torque and a reasonable speed
4.  they require no additional components (like H-Bridges)
5.  they don't require "constant" care... by this I mean that a servo only needs to be sent a comand every 20ms, so if you are using a single threaded micro processor, you can send a command, then go and do something else (like check a sensor) before you need to send a command again

annoyin_kid:
ohhhhhhhhhh!!! thanks steve

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