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Offline ktsheoTopic starter

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New and Need some ideas
« on: January 14, 2012, 09:07:39 PM »
Ok, so I am pretty technically inclined but not the most when it comes to robotics.

I am trying to create a simple device remote controlled that will adjust the throttle of a small gas engine.
The remote would have about 2 functions. Kill and up/down throttle. the smaller the better also.

I see the throttle controller being something similar to how the front linkage of an RC car works. (gears or levers)

I thought about tearing part a simple RC car and making it, but I need something that can transmit at about 300 feet (direct path). The motor/ throttle controller has to be to be strong enough to pull the linkage of the carburetor on the small gas engine.

Thoughts???

Offline ktsheoTopic starter

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Re: New and Need some ideas
« Reply #1 on: January 15, 2012, 09:22:16 AM »
OK... so  I did a little more looking around. 

I am looking for a simple homemade 4 channel remote/transmitter and a system to control 2 servo motors

The remote needs to be no larger than 4x4x1.5 and have about 3 switches on it.

check out my quick sketch (Paint).

Still need some help!

Thanks!

Offline Soeren

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Re: New and Need some ideas
« Reply #2 on: January 15, 2012, 02:06:46 PM »
Hi,

I am looking for a simple homemade 4 channel remote/transmitter and a system to control 2 servo motors
Going for pushbutton control, you'd just have full on/off - is that what you want?
You may find it easier to use a cable from a servo horn/arm, rather than a rack and pinion setup.

You can buy simple 4-channel sets with a key chain transmitter cheaper than you can build it yourself and HF is absolutely not for beginners.

An small to medium size cheap R/C car does not have the strength for this and before choosing a servo, you need to measure the needed pull strength of the gas flap (use a luggage scale).

The kill button should probably be a relay with wolfram/tungsten contacts or have serious snubbing at the contacs.


The remote needs to be no larger than 4x4x1.5 and have about 3 switches on it.
4x4x1.5 what? feet, inches, centimeters, mm?
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline ktsheoTopic starter

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Re: New and Need some ideas
« Reply #3 on: January 16, 2012, 08:40:45 AM »
Soeren, Thanks for the help!!


Going for pushbutton control, you'd just have full on/off - is that what you want?
You may find it easier to use a cable from a servo horn/arm, rather than a rack and pinion setup.


I would think something like a momentary on/off/on would work best for me (similar to electric windows in a car) This would allows me to turn the servo in either direction (throttle up or down).

I am guessing a "servo horn/arm" would be something like a 180 or 90 or 60 degree rotation?  I thought about that but I was not sure what kind of distance I would need cable to pull.

As for the "strength" it would need, It is not much at all. most of the time, the throttles are very sensitive


You can buy simple 4-channel sets with a key chain transmitter cheaper than you can build it yourself and HF is absolutely not for beginners.


The kill button should probably be a relay with wolfram/tungsten contacts or have serious snubbing at the contacs.


The remote needs to be no larger than 4x4x1.5 and have about 3 switches on it.
4x4x1.5 what? feet, inches, centimeters, mm?


As for the 4channel transmitter that you speak off... you have a link to what you have in mind?

The Kill button would not be hard to do, I figured a relay like you said would be simple enough. I am not too worried about the kill switch (yet).

For the transmitter, those dimensions are in Inches (sorry for the confusion). I just want something the size of a cell phone or something that can be held in one hand or clipped to a belt and not be awkward.

I am a fast learner, if you have any products in mind, feel free to share the links!

Thanks again!

Offline Soeren

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Re: New and Need some ideas
« Reply #4 on: January 16, 2012, 08:00:53 PM »
Hi,

I would think something like a momentary on/off/on would work best for me (similar to electric windows in a car) This would allows me to turn the servo in either direction (throttle up or down).

I don't know how you need to apply it of course, but with linear control, you could do the same, just with variable speed.


I am guessing a "servo horn/arm" would be something like a 180 or 90 or 60 degree rotation?  I thought about that but I was not sure what kind of distance I would need cable to pull.

Well... You're the only one of us who can actually measure it *nod-nod-wink-wink-know-what-I-mean*


As for the "strength" it would need, It is not much at all. most of the time, the throttles are very sensitive

"Not much at all" compared to what? The pull strength of an ant or of an elephant?
(This is why we have evolved measuring standards/references during most of the time man has existed) ;)


As for the 4channel transmitter that you speak off... you have a link to what you have in mind?

I'll have to dig one up in my link collection, but I just got another thought...
If you're going to use a servo (which you aren't if it's gonna run all day), an R/C TX/RX set like this can be bought for $23,- in both 4 and 6 channel versions (same price), it gives you linear control (if you want it, on/off as well) and you cannot get a 4 channel push-button set cheaper (most are a fair bit higher).
You just plug the servos into the receiver with nothing extra (except power) and Bob's your uncle.

Another thing is the environment it's gonna be used in. If it's a Rough&Tumble wotkshop with a concrete floor, you may need something more rugged or you could build it into a sturdy box made for taken some abuse.
That way you can pack the internals of the transmitter into a smaller box as well, as I assume there's a lot of air inside the box, but it's made a size where you can hold it in both hands when controlling whatever, with a thumb on each stick.


The Kill button would not be hard to do, I figured a relay like you said would be simple enough. I am not too worried about the kill switch (yet).

You should be, as one day it might save an arm or a leg (or worse) from injury, so it's the most important part and should be given top priority.


For the transmitter, those dimensions are in Inches (sorry for the confusion). I just want something the size of a cell phone or something that can be held in one hand or clipped to a belt and not be awkward.

For on/off only you can get it much smaller


I am a fast learner, if you have any products in mind, feel free to share the links!

Just on/off with a small transmitter...
Receiver:


Transmitter:


A more rugged transmitter:

Beltclip for this:

The site is a little confusing and doesn't give price info, so don't be surpriced if they cost an arm and a leg plus your soul and then some.

The size can be judged from this pic:


You cannot use this readily with R/C-servos, but a regular DC motor may be a better solution after all.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline ktsheoTopic starter

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Re: New and Need some ideas
« Reply #5 on: January 16, 2012, 11:52:15 PM »
This is great stuff!! thanks!

Ok... option A) The "Hobby King" cheapo
  • The transmitter would have to be "repackaged" for something smaller and more rugged
  • The transmitter hast to be water proof, so I am thinking that would be hard to get this version to be able to do that.
    • I like how simple the receiver is!
    • this one is the only one that I can see servo direction change occurring easily. What about the others
Option B) "Seco-Larm" 4 button transmitter
  • The size and style is perfect for what I am thinking
  • Can the buttons be "easily" programed to control a horn/arm? how can I get to change directions?

Option C) http://www.solidremote.com/products/69-rf-remote-control-transmitter-3-channel-w-50-150m-range-waterproof-model-sr-tx-113.aspx
  • The fact this one is water proof makes me really like this one!
  • Is the matching receiver as easy to use as option A?

Back to the "kill switch" the reason I am not too worried about it is because my "project" will have 2 people... one controls the throttle from a distance away, and another "supervises" the engine. There is also no blade on this engine... (sorry for being secretive)


Offline ktsheoTopic starter

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Re: New and Need some ideas
« Reply #6 on: January 17, 2012, 01:00:05 AM »
I wanted to add that I want the throttle to increase and degrease much like you shift a transmission. I dont want to have to hold a button to stay at a throttle I want to increase the throttle either by holding and increasing and when I let go, it stays there.(same concept on decreasing throttle)

This is why I thought a rack and pinion would be a good idea bc i could just turn the servo for however long I want, let go and it would stay there, reverse the survo and it would degrease and stay there.

If a horn/arm servo can do this, than that is an option too.

Offline newInRobotics

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Re: New and Need some ideas
« Reply #7 on: January 17, 2012, 01:37:50 AM »
If, say, You decide to go with bowden cable between the engine and rack/pinion setup, I'm not sure that it will withstand tension as rack can be moved by pinion as well as pinion can be moved by rack, meaning that servo will have to be powered all the time to counterforce spring loaded throttle.

Why not simply use DC motor with worm gear and pinion setup? With high torque low rpm motor and ON/OFF type (nonlinear) transmitter You will be able to adjust throttle and not to have all-day powered servo. With linear type transmitter You will be able to achieve greater precision.
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Offline ktsheoTopic starter

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Re: New and Need some ideas
« Reply #8 on: January 17, 2012, 02:23:25 AM »
Thanks for the idea. I figured I would have a servo with a gear reduction low enough that it would provide low RPM's and smooth throttle control and provide plenty or resistance against the spring of the engine's throttle.

Like I said, engine throttles are typically very sensitive! a pinky finger can easily provide enough force to move the throttle.

I am also now thinking about making a tracked actuator. A simple geared servo spinning a threaded rod that has a moving platform with internal threads that would slide up and down the threaded rod as the servo spins.

Make sense?


I am already learning a lot and i feel pretty quickly! Thanks! Keep it coming!

Offline newInRobotics

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Re: New and Need some ideas
« Reply #9 on: January 17, 2012, 03:13:25 AM »
I am also now thinking about making a tracked actuator. A simple geared servo spinning a threaded rod that has a moving platform with internal threads that would slide up and down the threaded rod as the servo spins.

Make sense?
I was just thinking about that.
It would increase space required. If that isn't a problem, then go for it.

Why do You want to go with servo so much? DC motors are cheaper.

What sort of signal does receiver output?
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Offline Soeren

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Re: New and Need some ideas
« Reply #10 on: January 17, 2012, 07:58:19 AM »
Hi,

Ok... option A) The "Hobby King" cheapo
  • The transmitter would have to be "repackaged" for something smaller and more rugged
  • The transmitter hast to be water proof, so I am thinking that would be hard to get this version to be able to do that.
  • I like how simple the receiver is!
  • this one is the only one that I can see servo direction change occurring easily. What about the others

It's the only one, of the 3 mentioned here, that you can connect a servo to without further circuitry, but (most) servos are not very rugged and was not build to do daily 8-hour duty.

The others (at least #2) can connect to a (gear head) DC motor used as you originally depicted it.


Option B) "Seco-Larm" 4 button transmitter
  • The size and style is perfect for what I am thinking
  • Can the buttons be "easily" programed to control a horn/arm? how can I get to change directions?

Yeah, I gathered that it would appeal to you, I just shy away from stuff that doesn't show a price, as it always mean "more expensive than it has to be".
But it does look like it would be a good solution in a workplace (the pad-like one with the optional belt clip, not the key ring model).
There is nothing to program. Each button makes one of the receivers outputs feed 12V to whatever you connect.

Each output can switch up to 10A(!) at 24V and it won't be much difference when using 12V.

As it says...
Quote
4 Separate Channels / 4 Output Modes Each:

    a. Timed Momentary (1, 2, 3, 4, 5, 10, 30, 60 sec.)
    b. Toggle (On/Off)
    c. Latch (Output stays on until manually reset)
    d. Continuous or Validity (Output for as long as signal is received)

All outputs are independently controlled. (i.e. Channel 1 can be toggle, Channel 2 can be one second momentary, etc.)

That's the only "programming to do and it is is done like this:
Quote
Mode switch (one per channel):
Enter Learn Mode:    Press tact switch.
Learn Transmitter Code:    Within 15 seconds of entering learn mode press button 1 and hold for 3 seconds.

Whatever it means exactly you'll have to check the user manual about, but I guess it's for pairing the transmitter to the receiver. How the modes are selected will be in the manual as well.

One thing you can't do with it, is having different timed values. The timer is common to all momentary outputs, but I believe it is of no concern to you, as you'd most likely be using mode "D" for the direct control.


Option C) http://www.solidremote.com/products/69-rf-remote-control-transmitter-3-channel-w-50-150m-range-waterproof-model-sr-tx-113.aspx
  • The fact this one is water proof makes me really like this one!
  • Is the matching receiver as easy to use as option A?

Waterproof can mean so much... The #2 choice is described as...
Quote
Extreme Durability - Rubber buttons eliminate damage caused by electrostatic discharge and helps make transmitter water resistant. Gold-plated battery clips and contact points extend the life of the transmitter.

At least it's splash proof (I don't know the IP rating for either), but using gold plated battery contacts is a mistake, they should be nickel plated to minimize the possibility of electrolytic material migration (not that it will matter all that much, you ain't supposed to use the remote under the hot shower anyway).
This "option C" is a wholesale business and you'd have to take at least 200 pieces and select receiver(s) to match. In my opinion this one looks too small and too fragile for real work.


Back to the "kill switch" the reason I am not too worried about it is because my "project" will have 2 people... one controls the throttle from a distance away, and another "supervises" the engine. There is also no blade on this engine... (sorry for being secretive)

You be the judge of that, but any moving/revolving machine is potentially dangerous. Not as much when you're alert and it's all new, but when things get old hat, people starts to lax and then bad things can happen.
There's a reason for safety light curtains around machines in most industrial settings.
But as said... You be the judge :)

How will it take over the world without revolving blades?... Minigun? Grenade launcher? ;)
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline Soeren

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Re: New and Need some ideas
« Reply #11 on: January 17, 2012, 08:22:40 AM »
Just a few comments to the other posts...

We still haven't seen any hard data on the needed power, nor the length it hs to move??

Bowden cable is used in some cars for the clutch! (But the cable is many times the diameter of a bicycle gear/brake cable).

There's a lot of ways to shave this goat, but to be easy on yourself, don't be too inventive - simple is often the most stable.

Having to keep the button pressed will be an extra safety, like a Dead Mans Handle, so shouldn't be discarded too lightly.

Servos will die screaming in a short time, the motor in a servo is ridiculously small and not of a very good quality. Servos are build for occasional Sunday afternoon flying/driving/sailing.

Don't degrease your transmission! ;) :P ;D

If you want a linear actuator, nick the power seats in your boss' Beamer/Mercer/whatever - or get a similar Acme screw and nuts.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline ktsheoTopic starter

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Re: New and Need some ideas
« Reply #12 on: January 17, 2012, 09:04:55 AM »
Ok... so there is a lot to process here lol

Start with this... I would probably do a DC motor. I was not sure how much current some of these receivers handle and I am familiar with servos being used with RC.

The transmitter must be water proof. My project will be used for water recreation. (one more hint  :D)
 - So option C is the closest thing. (but I have the ability to make my own waterproof box for a transmitter). Obviously a prototype will be a good start.

Question: from that website, is there a Matching receiver you see??

Question: would I want...
 Fixed Code    or    Learning Code    or   Rolling Code  ???

Again, I understand the reason for having a throttle that you need to hold down, but this is something that will control speed of another mechanical device.... like having a conveyor belt with multiple speeds :D You want to be able to set it and get back to work. :D No my project is not a gas powered conveyor belt haha but I hope you see the picture.


I apologize for not giving data on the distance and strength require, but I dont have a small gas engine to test it on. I am estimating that it will have to pull MAX of 4 inches and no more than 1-2lbs.   

I really appreciate the help guys. 

Thanks for the tips about a the actuators... I have abilities to make one to my specs and I have no boss that drives a Beamer lol

Offline ktsheoTopic starter

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Re: New and Need some ideas
« Reply #13 on: January 17, 2012, 10:29:16 AM »
I found this!! http://www.rfcontrolsystem.com/index.php?main_page=product_info&cPath=360_246_275&products_id=482 
this may be the perfect combination!  thoughts?

Offline ktsheoTopic starter

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Re: New and Need some ideas
« Reply #14 on: January 17, 2012, 10:46:22 AM »
I may have spoke too soon about that last one... it may not have the distance I need.

 


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