should I use servo or stepper motor for locomotion

jenko

Hi all,
could some one please help me with the following. I am new to robotics.

1. should I use servo or stepper motor for locomotion. I intend to use two rear
··· motors for differential drive and steering.

2. I need to carry a weight of 10kg on a flat surface at apprx 1.5 feet/sec. what should be the load torque of my motors.
··
3. can you point me to some good links where I can find info regarding hw to use a infra red emitter/detector
·· pair[noparse][[/noparse]not of parralax make] with BS2 mC for remote controlling my robot.
··

Post Edited By Moderator (Chris Savage (Parallax)) : 2/23/2007 3:49:35 PM GMT

Warrlok

DC motors and stepper motors reqire the use of motor controllers , servos can be controlled with just a BS2 but servos are not meant for continues duty they overheat and if u use servos u,ll be looking for continues rotation one but most can be converted to CR 10kgs if u have a good base and the weight is not resting on the servo,s shaft 4 of the parallax CR servos would do but
i would expect it to last to long sounds like u might need to go to gearhead motors

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Zoot

www.robotmarketplace.com/store.html has lots of powerful gearmotors -- some of which should be great for your purposes (10kilos is not a small payload). Combine some of those motors with the Parallax HB-25 motor controllers or the Devantech MD03 motor controllers and you'll be set.

Not sure I understand your IR question -- you want to use IR for remote control? Indoors I guess (flat surface)? What kind of control do you need? You have a number of options if indoor:

- use a TV remote (IR) and some IR detectors, plus some code to interpret the IR sent by the remote

- use a regular R/C (Radio Control) transmitter and receiver -- like those used for remote-controlled cars, plus some code to interpret and use the R/C signal

- wireless Playstation controllers (search the forums -- there are a number of threads on this topic, plus a good Nuts n Volts article by Jon Williams on using an SX micro to handle the PS2 controller)

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jenko

hi,

thanks for your replies.

can I create my own motor controller using bs2. does it require special hardwares? or only softares are the trick to do it.
if i use of those geared motors from the website-can I control them with bs2 alone?

I have two ideas for the locomotion part of the robot:
1. use two continuos rotation servos at the rear to provide forward motion and turning abilty.at the front I would use a static or castor wheel.
2. use a fixed stepper/dc motor at the font[noparse][[/noparse]only one] and use a servo at the rear to rotate the two rear wheels for turning abilty.

with 10 kg load and need of rather sharp turning ability-which approach should be good.

my robot would have to run for 15 minutes continuosly.must find and extinguish candles and pot red/green colored balls in baskets-while
avoiding obstacles and no entry zones. must enter the competion zone following a line.

i am still in the locomotion part of this thing. lots quesions are on the way :-)

jenko

Post Edited (jenko) : 2/17/2007 7:01:00 AM GMT

Zoot

Sounds like this is for a firefighting contest? Do you really need to carry a large payload for the contest?

Somebody said...
can I create my own motor controller using bs2. does it require special hardwares?

For DC motors YES you will need hardware, for servos, NO, you don't need hardware and can use just the BS2

If your robot will not be that big, continous rotation servos will be fine.

You might want to start checking out projects that others have built to get some ideas.

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When the going gets weird, the weird turn pro. -- HST

jenko

Thanks Zoot,

actually the contest includes firefighting, line following, obstacle avoidance, object detection/potting in the right place,maze..... it is a hybrid of all popular types of robotics contests.

we intend to use duel ccd camera for stereo vision·with onboard laptop for image processing and multiple BS2 for
sensor data processing, hardware control. the robot shall also have to carry battery[noparse][[/noparse]12v], firefighting equipments, mechanical
scoop/arm etc.

may be the weight will not be more than 5/6 kg. but we wan't to purchase motors with good safety margin.

I have got the infrared part sorted out.
*still need advice on how to develop a stepper and DC motor controller with BS2. any good links?
*also could you please suggest me any robotics simulator-where we could test various algorithms in a customizable environment.

thanks

j



Post Edited (jenko) : 2/19/2007 8:56:36 AM GMT

Zoot

Simulators someone else will have to speak to -- I know there are some out there, and MS Robotics Studio does this, and I think someone wrote a simulator for the Boe-bot, but this is not a subject I've explored.

Stepper and DC motor controllers are sold by Parallax -- www.parallax.com/html_pages/products/motorcontrol/motor_control.asp. The HB-25s are the super heavy-duty controllers for big DC motors. There are controllers there for a range of DC and stepper motors.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
When the going gets weird, the weird turn pro. -- HST

Henrymou

Personally, i am new to robotics 2.
don't use dc motors(the ones in your garage)
use servo motors for an uncomplicated project, like a robot
it seems that some strong servos are required for your robot that is 10kilograms
do all your caluculations in metric!
stay here on the forums for great responses at even 1:00 in the moning
NEVER EVER GO TO roguerobotics.com!
their coustomer support is (expletive)!
THEIR products are stupid!
I FREAKING HATE THOSE GUYS!!
good luck
-Henry the master