Sabertooth 2x25, and wheelchair motors

[jfischer]

I am going to be building a bot to move things around and decided to use wheelchair motors for it, and  control by R/C.

What I am wondering is I have read some on the Sabertooth, and looks like the R/C mode should work for me. Going to be using a Spektrum receiver, and a BEC for it to power the receiver off the 24 volt batteries.

The radio and receiver are both three channels, have the choice of using a Futaba 3PK or a Spektrum DX3R radio I have, of which both have extra channels I can program for other things.

One questions for those that might have done it, and running the Sabertooth in the R/C mode, what are you using to release the brake on the motor? I could use a relay, and be able to turn it off or on from the radio before wanting to move the bot, or are you hot wiring it so when you turn the main switch on that it gives power to the two brake wires on each motor to release them.

Just wanted to get some input on what might be best.
Jeff

[SmAsH]

do you still want the brake to be there? most of the blogs/sites ive seen the people have just broken the brake off as you can just make the motor brake on its own.

[jfischer]

I am not talking about the mechanical brake, but the electronic brake here, ususally the two white wires which are used when the chair is just sitting there so it won't roll when the chair is turned off. (I would assume you just run positive voltage to them to release them, like other motors I have seen that use a electronic brake)

This will be a heavier bot, as it is not a fighting one, and is going to be used to carry things, and will be in the weight range from 200-300 pounds, and I have some small hills where this will go, and will use it to load or help me get things into my trailer,  of which has a ramp door, and I might want to have it half way up the ramp and stay in place. I don't think that if the power was turned on it would stay in place on a ramp, or small hill if there wasn't some kind of brake still available.

Guess that is why I was asking here, as I had seen relays I could use, and put it on the 3rd channel to activate it if needed.

do you still want the brake to be there? most of the blogs/sites ive seen the people have just broken the brake off as you can just make the motor brake on its own.

[SmAsH]

do you have the wheelchair motors with you as you could always test whether voltage going through it does anything? and do you know what brand/model the motors are as you could look up the datasheet as it may have something along the lines of what you want.

[Razor Concepts]

Any reason why you want those 3 channel land based radios? You could get a DX6 or DX7 for just about the same price.

[jfischer]

Because I have them, and hate stick radios. I am not flying a plane, or heli, and have gotten used to driving with a wheel radio after racing for many years with them, and they have as many mixes as the air stuff does.
Why might you ask?

Any reason why you want those 3 channel land based radios? You could get a DX6 or DX7 for just about the same price.

[aludra_55]

I just bought a DX7 about 3 weeks ago and it costs $339 including the receiver, charger, battery, and 4 standard sized servos.  Anyway, I think that Sabertooth has an electronic brake mode that would prevent movement.  Probably check the datasheet on your Sabertooth.  I have the 2x10 version. 

After reading your post a second time, it appears that you're talking about a totally separate device that prevents the wheels from moving.  It appears that a separate channel controlling the relay would be a good idea.  But then again I'm still a newbie.  =)

[tank]

Hi,

Has anyone here tried the sabertooth 2x25 with PPM servo.write comands from the arduino? Will that work flawlessly? In my point of view, that is the easiest way to control the saber..but hopefully it works.

Which is better. PPM or PWM with the sabertooth?


Any form of help would be greatly appreciated