Hey guys.. I know just enough so far to get me in trouble
My question is, I picked up a bunch of the firgelli PQ12 linear actuators. I have been doing some reading to figure out what needs to get done to get them interfaced with an arduino (since they have no actual motor control built in). These are the ones with potentiometer feedback.
here is the spec sheet
link 1 in the next post (since I am not able to post links since this is my first post lol)
So as I understand it, the actuator has two power lines, supply positive to one and negative to the other, and the motor goes in one direction, reverse that and it goes in the other direction. I have been going over many different options.
Option 1 is a H-bridge type motor controller, but they are designed to deal with large amperage, and I think these actuators use up to 550ma. So being able to drive 2A for 2 motors would be pointless. Also, I need to drive 10 of these actuators. So a lot of h bridge motor controllers would cost a decent amount.
Is there a single chip solution I could use like a L298N? Or this little guy?
link 2 in the next post
I would much rather use one that is already setup to use serial or PWM to control them. Possibly something like this that can run more than 2 motors and doesnt need to drive 2A per motor
link 3 in the next post
I know this post seems all over the place.. thats how it is when I brainstorm.. stuff just flys around inside my head till something sticks lol
Would you be clearer about what you need?
Let me try to summaries:
The actuators need to be driven in both directions, so the voltage on the connectors will need to be reversed.
The actuator needs 550mA at 6V.
There are 10 actuators that need to be driven.
Do you want to control the speed of the actuators (e.g. with some form of PWM)?
Do you want the position feedback from the built-in potentiometers?
If you do want position feedback, do you want it from all 10 actuators?
Do all of the 10 actuators need to be driven simultaneously?
Yeah I know it wasnt the clearest post ever.. I was brainstorming and searching as I was typing it
to answer your questions, really, yes to all.
10 actuators at 550ma 6v
Speed of actuators would be great
all 10 should be able to be driven at once
potentiometer feed back would be important for limiting travel but could probably be handled by the arduino instead of the driver?
The L293 will handle the current with a nice margin of safety. Each L293 will drive two motors. You will need external port expanders or shift registers to control them all.
Pot feedback for ten actuators is going to require some sort of external A/D or muxing in order to get them all in.
The safest way to rig things is with some sort of inline limit switches to stop the actuator movement as the ends.
10 actuators at 550ma 6v
Speed of actuators would be great
all 10 should be able to be driven at once
potentiometer feed back would be important for limiting travel but could probably be handled by the arduino instead of the driver?
To reverse the travel, you'll use H-Bridges (or equivalent, I can't find the parts I was thinking of :-()
The SN754410 is cheaper if you shop around then variants of L293's which have back-EMF diode protection built in, but, you'll need diodes for back-EMF protection (so cheaper, but more board area).
The SN754410 and L293D are pin compatible, so you could change part way through.
As rocketgeek says, you can drive two motors with each chip.
With external logic inverters, you can get the control pins down to 2/actuator, one for forward/reverse and one for a PWM signal.
You could use shift registers, and if PWM speed control isn't needed, that would be a fine way to go.
If you do want PWM speed control, it might be as easy to make yourself a second Arduino, talk to it over I2C or SPI, and have it control half, or more, of the actuators. This approach would also give you plenty of analogue inputs for the potentiometer feedback.
If you need lots of PWM, you could use the TLC5940, which gives you sixteen channels of sink-mode PWM. There's even an Arduino library to deal with its oddities.
If I were you I would get some of the below el cheapo servos and use the boards from them to drive the PQ12 actuators. The motor in the below servo probably pulls more current at stall than the actuator motors, so the h-bridge should be safe. Just abandon the motor and pot in the servo and connect the servo board to the motor and pot in the actuator.
If I were you I would get some of the below el cheapo servos and use the boards from them to drive the PQ12 actuators. The motor in the below servo probably pulls more current at stall than the actuator motors, so the h-bridge should be safe. Just abandon the motor and pot in the servo and connect the servo board to the motor and pot in the actuator.
The Toshiba TB6612FNG is used by Polou in their robot controllers. Those folks are pretty smart.
I've bought five to experiment with, but haven't got round to using them (too many projects on).
Are you willing to try surface mount soldering?
If you are then you could get the chips straight from Digikey
They are only $2.07 each.
If you can make PCBs, then you could make your own driver board.
If you can't then you could get 24pin SSOP24 adapters for abut $0.70 each, and make your own solution.
The Toshiba TB6612FNG is used by Polou in their robot controllers. Those folks are pretty smart.
I've bought five to experiment with, but haven't got round to using them (too many projects on).
Are you willing to try surface mount soldering?
If you are then you could get the chips straight from Digikey
They are only $2.07 each.
If you can make PCBs, then you could make your own driver board.
If you can't then you could get 24pin SSOP24 adapters for abut $0.70 each, and make your own solution.
HTH
GB
I tried smd soldering once.. it was ugly lol I dunno if I should try again.
I was thinking about this polou, but its a little pricey
it has the ability to daisy chain them together where the $8 one from sparkfun doesnt I dont think.. but thats 3 times the price
Sparkfuns approach of choice is an electric skillet. I use a toaster oven and a multimeter with a thermocouple. The advantage of the toaster oven is it's a bit easier and safer with children. A local school teacher showed me the technique, and he gets extremely high success rates with 11 year olds.
You apply solder paste to the board (like micro-miniature cake icing), place the parts on the board, and 'cook'.
When the solder paste melts, surface tension aligns the parts.
If you put too much solder on, use a piece of solder braid to remove excess.
It produces a lovely finish.
Using the Futurelec adapters, you could make 5 H-Bridge boards pretty cheaply.
The servo's control algorithm was so incompatible that it oscillated and vibrated.
Large motors may not play well with PWM power (if it was a large motor being used). I think they prefer to be solid on/off. The below is sitting in the corner awaiting some monster servo tinkering. Possibly ~2,000in-lb torque at ~150 amps.
