Go Down

Topic: Driving Linak actuator and 4 Electric braking Castors with a Joystick (Read 1 time) previous topic - next topic

Peted

Hello, I am designing a Electronic Lift office chair with Electric Brakes. I have all the main parts but to cut costs down would like to use an arduino board to make it all work.
Parts:
1 x Zippy Joystick - 4 x micro switches
1 x Linak BL1 Actuator
4 x Trinity Electonic Braking Castors (each one driven by a small servo motor)
1 x Linak BA18 (Rechargeble battery) - 24 volt

I have attached pdf's with information regarding actuator, EBC's and battery

On the Joystick we are wanting to use:
UP - as unlock all 4 braking castors
DOWN - as lock all 4 braking castors
LEFT - as making actuator go up
RIGHT - as making the actuator go down

My question is how do I put it together and what extra parts do I need?
What code would be the best code to use or would it need to be written specifically?

JimboZA

It's not clear (to me, anyway  8)) if you're using the joystick itself as the hand-control or merely the switches....might be worth clearing that up to get suggestions.
Arduino ethernet server here.... http://jimboza.gotdns.com:8085/

No PMs for help please

JimboZA

I'd suggest the first thing to do is to get the joystick working- most are simply 2 potentiomenters are right angles.

This tutorial explains how to read a pot.... check the data sheet for your joystick, but it's likely that you just need to double up the code in the tutorial sketch, using a different pin for each axis of course :) and using variable names like sensorValueX and sensorValueY.

Then you can at least see that you can read the joystick on both axes.
Arduino ethernet server here.... http://jimboza.gotdns.com:8085/

No PMs for help please

Paul__B

Muscular dystrophy it is actually, the spelling.

As in all such projects - any project - you need to take it one step at a time.  I would suggest testing your algorithms with a simpler emulation, such as getting your joystick (which I suspect is actually a switch array rather than potentiometers, but may be wrong) to smoothly operate a servo in one dimension.

Your concern here is a variation of "debouncing" - if it is in fact switches, you not only need to compensate for contact bounce, but on a second level probably have to compensate for enhanced physiological ("essential") tremor so that you can obtain smooth operation of the servos not just when you manipulate the joystick, but so that the intended user can achieve the same effect - this requires rehearsals.  When you have it working on one axis, go to two axes on the test rig - two servos - then swap the servos for your final effectors.

Note that servos generally consume power continuously to hold position - I haven't looked, but check that out with what you will be using.

And you need a switchmode regulator to efficiently power your Uno from the 24 volts.

JimboZA

I had a quick Google... at work so didn't spend too long, and looked at some photos.... it seems to me that the joustick might merely be 4 switches, one in each direction, and simply therefore an on/off on each direction. I may be wrong: should be easy to fathom out with a meter across the terminals?

If it IS simply 4x switches, then it's a much simpler proposition I reckon.
Arduino ethernet server here.... http://jimboza.gotdns.com:8085/

No PMs for help please

Paul__B


JimboZA

Arduino ethernet server here.... http://jimboza.gotdns.com:8085/

No PMs for help please

LROBBINS

Only one suggestion for now.  As you just want to drive the Linak up or down with no control over speed etc., I'd suggest using a pair of 24V SPDT (automotive type) relays in an H-bridge configuration. 

e.g. Mouser 893-896H1CHCR1U2424V (these particular relays have built-in snubber resistors, you will have to add a driver transistor (NPN low-side switch is simplest) to go from the Arduino to the relay coils.

Simpler and cheaper than designing a MOSFET H-bridge for 24V, and wired up as in the attachment (clipped from a larger schematic, but should give the idea) shorts the Linak motor when not driving, hence providing braking.

Add a couple microswitches and diodes as limit switches.

Ciao,
Lenny

Go Up