Servo Positioning Values

Question

Afternoon All

I'm having trouble getting any positioning on my 180 degree servos. No matter what values I put in the unit does a complete arc. I can add speed control but that's about it. My goal is to use the servo to open a panel door. I could live with the complete ARC but would rather limit the range.

Any advice is welcome.

Thanks,

Daniel

edison2 · Answer

Can you give us the model of your servo?

Dave Schulpius · Answer

Hi Daniel, How are you moving this servo? With a movement panel or script? Can you post a copy of your project? You'll find it somewhere in your EZ-Robot Inc folder and have a .EZB extension. Just use the "Attach File" tool in the lower right hand corner of your screen and upload it. I'd love to take a look and test it to see if there is anything I can see. If your using a script this is an example:
 Servo (servoPort, position) Move servo to the specified position Servo position is between 0 and 100 Example: Servo(D14, 25)

If using a movement panel make sure you have your ports inserted right. Good luck, Dave Schulpius

R2D2 · Answer

For radio controlled aircraft with retractable landing gear, there are some specific servos with tours of: 180 degrees (all or nothing). These Sevos not allow variations in the rotation and can only move from 0 to 180 degrees without intermediate positions. I wonder if you're using one of those servos, to rule out other problems.

Mulberry · Answer

This is a standard servo that came in the EZ kit. Model is S08NF STL. I'm not using script but a movement panel. My current settings are below. No matter what locations I use (and I've tried all combinations) the servo still does a complete 180 arc. Daniel

Rich · Answer

The control you are using is for a modified servo control not a standard servo control. Click on project Add Choose Servo Select either Horizontal or Vertical servo depending on it's orientation  Click on options and adjust the port, min and max values  Alternatively you could use a script to open and close the door. You will need to figure out the servo positions but just adjust the positions I've used below (positions are the second part in brackets of the Servo() command) Open Door
 Servo(D4,100)

Close Door
 Servo(D4,1)

Mulberry · Answer

Thanks Rich. So I calibrated and now the question is how do I activate it? I've used the control panels for my modified servos but that isn't available with this. I've reviewed the videos but am stumped. I hit center and release but get no movement. Daniel

Rich · Answer

Once you have the Horizontal or Vertical servo control added and set up all you do is click on the big number in the box and drag left or right for horizontal (or up and down for vertical). Excuse the poor framerate (I need better screen recording software) but here's an example from start to finish.  P.S. A small tip and little known fact, in the video I right click on the servo positions in the config to bring up the list of positions rather than scroll through. The same can be done when changing the position on the control.

Mulberry · Answer

Thanks Rich. Still no movement from the servo and I get a disconnected message when I click on center or release. I assume the center and release are how I activate, correct? Daniel

Rich · Answer

Centre will move the servo to it's centre point (that being max position - min position / 2 so centre between max and min) Release will release the servo - when you move a servo to a position the control will hold it at that position (if you try to manually move it you will feel resistance, if released it will freely move). If you drag the number part and the number goes up or down the servo should move to the position indicated. I assume you have connected the EZ-B to the PC correctly? If you are getting a disconnected message it may be that you have an issue with the power somewhere. Either a bad servo (possibly, but worst case scenario) or the board is browning out due to a low battery.

Mulberry · Answer

Ok. Just had a major incident. I'm using a external 12 volt power source and thought my grounds should be connected such as with a H-Bridge. I did that and my servo wires melted. The board seems ok but I had to peel the fused mess from all over my work bench. Tough day

Rich · Answer

You should have a common ground for everything. I'd be checking all wiring not just grounds if that had happened. Melted cables usually are a sign of excessive heat, which usually indicates a short from Vcc to Ground.

Dunning-Kruger · Answer

Dude, are you sure your servo is rated for 12V? Most servos use max 7.2 volts (but yes there are higher voltage ones)... However, it sounds like you shorted something with bad wiring...

Rich · Answer

That's a point... The Servos in the EZ-Kit are not suitable for 12V. If you have applied 12V to the Vcc that could have been the cause of the problem. If they were plugged directly in to the EZ-B then you have nothing to worry about on the wiring side (12V power supply in to the EZ-B, Servo hooked up to the Digital port (Ground towards the centre)

Mulberry · Answer

Yep. Too many bloody wires and servos connections going on. I grabbed the wrong wires and connected to a 5 volt servo instead of a 12 volt. Totally my fault. I think I've figured out my blind spot. These servos are to be controlled by scrolling and not the center and release. I thought I would have a button to move the servo into one position and then a button to move it back. Is that it? Daniel Gonna be two martini's tonite.

Dunning-Kruger · Answer

Dudes drink beer, not martinis... ... My girlfriend drinks wine which in my opinion taste like battery acid, but that's just me...

Rich · Answer

If you are switching between 2 positions you may find scripting is the way to go, which would mean using 2 scripts (as posted earlier).
Servo(D4, 100)

Servo(D4,1)

You have the choice of script manager and EZ-Script (and keyboard, joystick etc. too I guess) so depending on how you add the scripts will depend on the way to use the controls. Here is a project with 2 EZ-Scripts, one called Door Open and one called Door Close. Download it, save it and then in your project choose Merge. Select the 2 scripts and OK it. They should be imported in to your project (on Desktop 1). You may need to adjust the port and position but clicking on the start button of each should move the servo in to the required position.

Dave Schulpius · Answer

@rryerson, wine and martinis make a great change of pace. Beer is good for watching a football game or cookout. However it's just too filling.

@Daniel, Sorry your having these troubles. Looks like your rounding the learning curve though.

Nice progress

Mulberry

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