Let's Make Robots!

Tilt sensor/switch for an RC rideable vehicle

The Project:  I am building a 1/4 scale radio controlled Ford F150 pickup.  The body style was chosen for me when I was given a free 1/4 scale fiberglass body.  The drive-power was originally going to be a small 2-stroke engine, but I was also given a free Pride Mobility Scooter/wheelchair that came without a controller or batteries.  Speed and direction control will be in the form of a SyRen 1X50 from Dimension Engineering, which in turn will be controlled from a common RC transmitter and receiver.

Here is my question:  I want to be able to do a little all-terain driving with this truck.  It won't have good enough suspension for rock crawling and such, but even so, I would like to add some sort of tilt-sense.  The truck will be large enough and powerful enough to be ridden on or to pull a trailer that is being ridden on.

 

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A note before we continue..

Yes, I joined this forum to ask this question.

Yes, I will very likely stick around this forum after this question is answered.

Yes, I am a beginner to 99% of this.

Yes, I am aware that my project, being radio controlled, isn't exactly a "robot" as these pages tend to define robots, however the equipment and techniques used are similar, so I am asking for help here.

Yes, I did do some searching, but, all that I found seemed irrelevant.

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I'm not entirely sure what I want the tilt sensor to CAUSE, either slowing down the truck or stopping it or reversing it or shutting it down completely, but I want something very simple.  I am more-than-willing to make my own sensors of the ball-in-tube style, but am worried about the ball bouncing around and causing false readings.

I understand that a potentiometer can easily be added to the SyRen to set the max speed.  Could a tilt sensor add a pre-determined voltage or resistance in place of the pot idea to simply put the truck in "half speed" if it tips too far?  If so, could a different voltage or resistance be assigned to each sensor so that more tip = slower speed or right/left tip - 1/3 speed and front/rear tip = 1/2 speed?  All this should be doable without logic, just using the sensors to switch more voltage or resistance into the max-speed input on the SyRen..

 

I'd like to know what you all think, good or bad, about all this..

 

Mike, from DieCastoms.

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car window wiper or power window motors will be strong and fast, google rc pocket quads and look at youtube also 

Yes, it finally arrived (this post is very late as I've only gotten to mess with things this week) on April 16th.  Not terrible, really, 19 days from placing the order..

I borrowed the RC out of a plane that we've had laying around and connecting the SyRen really IS as simple as DimensionEngineering makes it out to be!  I cut the pigtail off a broken servo..  black to ground, red to 5v+, and white to "S1" signal input.  + and - from a car battery to the appropriate terminals on the controller, and + and - from the scooter motor to the remaining screw terminals.  No soldering, no adjusting, no programming (had to flip one DIP Switch to put it in RC mode).  Hit the stick on the transmitter and immediately ran over my sneaker :D  Flip the servo-reverse on the transmitter and all was well!!!!

I CAN load a video if anyone cares to see, but at this stage the scooter still has no remote steering what-so-ever, and with someone sitting on it, it is no more than a mobility scooter..

I did learn that 12 volts will *NOT* be enough for what I want..  it is too slow and with someone sitting on it, it struggles even in grass on flat ground ...  will have to be 24 volt (as the scooter originally was) or even 30 volt if I can source an appropriate charger without killing my budget (which isn't much).

Next BIG step will be finding a servo for the steering.  Like the motor controller, I want enough overkill that I do not need to worry about breaking the gears, but also like the motor controller, I need to be able to afford the servo >.<  I have seen many that will work, but with price tags OVER $200 for a single servo, it's not really possible right now....  I have seen several accounts of people using modified servos for position feedback while using car window wiper or power window motors, but all seem to agree that there isn't enough power or speed..

 

So now I look to LMR for more advice!  I need a servo to steer this thing...  I HOPE to be under $100 for the servo...  I wont terribly mind using two servos but I am a little worried about the extra complication as well as the servos fighting each other.

 

Hoping to get plenty of replies,

Mike, from DieCastoms.

now that you are asking a different question you should make it a different forum post, if you want people to look at it. The other bonus is, people looking for answers to how to steer a heavy model with a servo or servo like mechanism will be able to find it rather than find a post about a tilt sensor and wonder what it has to do with steering.

but on the other hand, the one fact that keeps me from being pissed off is simply knowing that I am getting a BRAND NEW controller RIGHT off the assembly line.

 

Kinda neat to know, but I would rather have been informed when I ordered it, I shouldn't have had to email them and ask where my shipment was, they should have emailed me and notified me of a delay or there should have been notices at the time of purchase .... 

 

Oh well.  Spilled milk, right?

 

Mike.

Which company is it? 

I had ordered direct from Dimension Engineering

not sure if any of you care to know or not, but..  here's an update on my project..

I ordered the motor controller on March 29th.  It was nice of the company I ordered it from to never tell me that they were out of stock and that it wouldn't be shipped out for at least two weeks after I ordered it..  I had to email and wait a week for a response..

 

When the controller ever gets here, I will post another update.

Mike.

now you know you are dealing with a quality company. :P

Thanks again for commenting, airuno21.

By "RC" in this case I am referring to radio control.  I will try to be more careful about that in the future.

I suppose the way to answer your question about whether or not I would need to have a micro controller to handle the input is to simply say that there is one built into the motor controller..

The SyRen motor controller that I purchased has two inputs.  When set up correctly, the input referred to as "S1" uses zero to five volts analog to determine both motor direction and speed.  0 volts is full reverse, 2.5 volts is full stop, 5 volts is full forward.  Max Speed Mode allows you to connect another potentiometer to S2 and set the max speed.  If you set this potentiometer to 50%, the potentiometer on S1 will scale between 0% and 50% over the entire length of its travel.  What i was figuring was, if I supplied 2.5 volts to the tilt switch so that when the switch closed it supplied that 2.5 volts directly to the S2 input on the controller, it would put the controller in 50% max speed mode.  

 

Mike