|Jan 15, 2011, 06:43 PM|
Using old servo control boards as actuator driver/motor ESC for PROPORTIONAL control
Here is one little experiment of converting a toy car to proportional control;
Yep, both steering and throttle control are proportional. Steering is spring type, actuator driven;
The idea is to use the servo controller board as H-Bridge ESC drivers for the car motor. The same is also true for the steering magnetic actuator. The steering mechanism is spring centered thus you can actually vary the actuator magnetic strength to define the deflection of the wheels. This can be adjusted further by defining the EPAs and D/R rates on the steering channel at the TX side.
For the Main Motor, i used an old Futaba S3003 servo control board ...
For the steering actuator driver, i used an ESky 8g servo control board.
You need to retain the pots on the servo boards and adjust them for a 0-volt center on the motor/actuator output.
The setup is powered by a small 1S lipo thus a charging port is required;
a simple schematic;
Steering EPA at 30% on both sides.
Steering D/R at 40%
Throttle EPA at 30% on both sides. Motor achieving full rotation at such rate thus you only need to spread out the throttle curve on the entire swing of the TX throttle trigger Same case also for the steering.
Motor and Steering actuators in action as controlled by a Futaba 2.4Ghz FHSS
Table Top run testing proportional control on both steering and throttle;
Full tests on proportional control on both steering and throttle on the ground;
|Jan 16, 2011, 08:33 AM|
And since we already have the servo control board inside, we can actually replace the steering actuator control with a full blown micro servo using the already existing e-sky servo as motor drivers. This is done by connecting the motor and the pot that is built-in on the servo. Both actuator driven and servo driven steering mechanism can provide full proportional control. However, if you have access to a very small servo for your micro rc car,why not mount that one instead ?
Here she is again in action;
Proportional control tests done on the floor for both steering and throttle ...
and a good ol table top run also testing the proportional control;
|Jan 16, 2011, 08:54 PM|
Just to give a comparison and a couple of options too, here are a possible combination of this proportional control mod;
1. Kyosho AM transmitter with magnetic actuator steering. Esky 8g servo as steering actuator driver and Futaba S3003 board as ESC for the main motor drive.
2. Futaba 2.4Ghz + R603GF combo with with magnetic actuator steering. Esky 8g servo as steering actuator driver and Futaba S3003 board as ESC for the main motor drive.
* The programmable TX is actually a better option for the actuator steering as you can vary the strength applied on the magnetic coil by adjusting the D/R rates and EPAs.
3. Futaba 2.4Ghz + R603GF combo with full sub micro servo steering. Esky 8g servo as steering motor driver and Futaba S3003 board as ESC for the main motor drive.
Of the three options, obviously the 3rd one would be the best as it consumes less current than using actuators but it may be hard to access a good micro servo and specifically mount them on a very small scale car. Actuators work well on proportional steering as long as you can properly adjust the D/R rates and Endpoints so that you can maximize the entire steering wheel curve.
|Jan 19, 2011, 12:32 AM|
|Jan 21, 2011, 06:22 PM|
Here is a new one - Small Kart racer with the proportional control steering and throttle.
1. 1S Lipo Power
2. 2.4Ghz Efly RX/TX combo
3. 2 Servo Control boards - one for steering and driving an actuator and another one for throttling.
4. a couple of centering pots (5kohm) to put both the actuator and motor to 0 volts at tx center stick
Using the bulky TX with the programmable TX parameters
With the onboard electronics;
Electronics neatly attached;
Gas time (Lipo charger)
Proportional Control Actuator and Steering in action
|Jan 21, 2011, 08:20 PM|
|Nov 27, 2012, 07:36 AM|
Joined Feb 2005
I realize this thread is old and while the OP may not respond i would love some clarification from anyone on this subject. I'm just getting back into "micro" rc after many years.
I have a LOSI TX / RX combo from a micro T. If i am understanding EQMODS simple schematic correctly (hopefully) i would only need to purchase 2 servo boards (sticking with the example EQMOD gave - the Futaba 3003) in order to add proportional steering and throttle to any non proportional / magnet steering car. Is this correct? It seems so but i'm trying to shake the rust off as i ease back into the hobby.
BTW OP...i think the go kart is simply fantastic. I'd love to be able to create to fully proportional version of the vehicle for my loved ones to race with.
|Nov 30, 2012, 02:39 PM|
Joined Jun 2010
From your explanation your assumption sounds correct, one board for the motor, one for the magnets. Remember these are usually only for very small RC cars due to the limited power output of the boards though, anything much larger and you'd be far better off with a true brushed ESC and replace the magnets for a servo, even in these small RC cars I've replace the steering with a 2g servo from HobbyKing.
If you have some time to explain your intentions further with specific information you may be able to get some more valuable information.
|Dec 20, 2012, 09:05 AM|
Joined Feb 2005
Thank you very much for the reply. My apologies for late response but i've spent the last few weeks researching what would be required for a conversion from non proportional to proportional in a smaller rc and i've come to the same conclusion you offered in your advice (i.e. the 2g servo).
It's the preferred method to achieve what i want anyway as wiring multiple boards didn't fill me with enthusiasm (nor did keeping magnetic actuator steering). Hopefully i can utilize my LOSI rx as i'd hate to have to buy another. It boils down to whether or not the Go Kart pictured above is large enough (even after modification) to fit it.
Thanks again ! It's nice to know i can post a question here and receive some valued input
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