Giant servo question....
Hi!
I have two Giant scale, very strong (343 oz/in) servos, and i'm wondering, if i could use them, a GPS and a Stamp to control a 1/5 scale car to go on a specific route?
I searched the archives for servo projects, but every one of them uses modified servos.
I have a BS2sx and a BS2p24, and i don't want to modify the servos, because if anything goes wrong, then if a servo as strong like this goes over the "end" then it can brake many things.
in a few words:
Two srtong servos, a radio reciever, a 1/5 scale car, a BS2sx/p24, and a controller.
Please help me!
Many thanx
p.s.: i will use the Stamp to watch the voltage too:-)
I have two Giant scale, very strong (343 oz/in) servos, and i'm wondering, if i could use them, a GPS and a Stamp to control a 1/5 scale car to go on a specific route?
I searched the archives for servo projects, but every one of them uses modified servos.
I have a BS2sx and a BS2p24, and i don't want to modify the servos, because if anything goes wrong, then if a servo as strong like this goes over the "end" then it can brake many things.
in a few words:
Two srtong servos, a radio reciever, a 1/5 scale car, a BS2sx/p24, and a controller.
Please help me!
Many thanx
p.s.: i will use the Stamp to watch the voltage too:-)
Comments
Are you trying to race your car without controlling it on a specific track [noparse];)[/noparse] ?
A 'Modified' servo is modified so that it no longer allows you to select a position. Instead, the servo can run continuously (like a wheel) and you select the speed of rotation. Any time a servo runs a driving wheel, it MUST be a 'modified' servo. The nice thing about a 'modified' servo is that a BS2 can control them very easily, and the price is good too (compared to every other speed controlled motor approach).
So, if you are going to put them in your car, what is your car going to use for moving forward? Does it already have electric motors?
When 2 servo's are used in a robot, typically differential speed is used for steering. This wouldn't work very well in a model car. What you need is one powerful servo to drive the driving wheels, and one un-modified servo to steer.
I am a nitro modeller, and i use nitrous engine for driving the car forward, and the servos are for pulling the gas on the carb. and the brakes, and for steering the model.
So i need to get the servos working and positionable.
for someone's attempt at this problem. There are a couple problems with this approach. The heading· and bearing only update once per second in most GPS units. so most of the time is spent guessing where you are going.Also, since the Stamp spends most of its' time in a serin statement waiting for new GPS info, it only goes through its; loop once per second!
I now use one BS2 Stamp to read the GPS, and a BS2p to do everything else. The BS2p·Stamp uses the polled interupt feature to detect when the BS2 is ready to send info. You may want to use a compass or rate gyro to keep the vehicle moving in the right direction between updates.
As to the Servo being big, Our robot used a power window motor big enough to break your hand if it were in the wrong place.
'Larry
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I have a 2P and a 2sx, so it's possible to do it, just the controlling is the question for me! Thanx for the link.
btw: We do shows with the models, so it's enough to go slowly, because it's just for the show
And we are thinking about a "following act", and a Stamp is ideal for it
Post Edited (Paul Baker) : 2/7/2005 5:53:31 PM GMT
cordless screw driver for a very effective powerful servo.
Anyway since you already have your servo's you don't need to hack a cordless screw driver.
Years ago I made a large scale (20 inch wheel base) remote car powered by a gas weed eater. One of the biggest challenges
was steering. I decided to make a rack and pinion steering frame from stock aluminum. Then I needed to convert the
rotational servo (screw driver) into a linear servo. To do this I used a semi large spring (2 inch diameter about 5 inches
long with 10 turns) I welded washers (1/4 inch ID) on each end of the spring (used silver solder and a torch -- heat both
spring and washer until glowing, and then spot wick the silver solder until it flows between spring and washer) On one end
of the spring I connected the screwdriver via a 1/4 inch bolt (also welded). On the other end of the spring I used a 1/4 inch
steel dowel bent in the shape of an "L" . The short leg of the "L" stuck out past the spring coil and rode along an aluminum
guide track and wala a linear servo adapter that I could use to move the rack and pinion steering. (See images below)
Note: The spring was an added benefit to absorb steering shock on rough terrain.
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Beau Schwabe - Mask Designer III
National Semiconductor Corporation
(Communication Interface Division)
500 Pinnacle Court, Suite 525
Mail Stop GA1
Norcross,GA 30071
Post Edited (Beau Schwabe) : 2/8/2005 4:13:02 AM GMT