Cont Servo Question

Question

I am sure this is someplace ( I can find it with search)

I learning to use the tracking for ez v4 and I was wondering if is is possible to use the 360 servo to have cam track in a circle? I have been trying, but it seems once the cam picks up something it just spins the servo ( with no stops) with no real regard to anything and does not behave like the regular servo with tracking. Is this something that is just a result of the 360 servo or is it something I can fix?

CochranRobotics · Answer

no, it isnt possible without some serious scripting. A 360 servo looses the ability to know where it is at, and thus looses the ability to be used in such a manner. Scripting could make this happen but it could get very extensive.

JustinRatliff · Answer

@Jayutmb - A standard servo has a potentiometer inside (a variable resister) and as the servo moves the resistance chances and this is what allows the servo to be moved incrementally. A standard servo also has a mechanical stop to prevent it from mechanically moving too far either way. A continuous rotation servo has no mechanical stop nor the variable resister feedback. Based on the pulses sent you can still control speed and direction of a continuous rotation servo, but not where it stops. So given that, lets consider for a moment what it would do to your EZbv4 and camera if it were on a continuous rotation servo. Wires have to go from the camera to the ezb, so if it rotates around and around the wires will coil and break. You don't want that. I assume you are pondering a radar type unit on your robot that can spin 360 degrees but not continuously? One method might be to use two servos and two ultrasonic sensors back to back with 2 radar modules in ARC - this would give you 360 degree coverage. Also note most standard servos rotate greater than 180 degrees so set the stop points so they don't bang into each other.

jdebay · Answer

@justinratliff great answer, i agree. j

JustinRatliff · Answer

Another thought is use two servos on top of each other. One would be the radar servo with the ultrasonic sensor. The other servo on the bottom could rotate the radar servo from front to back facing position. You could then use one radar control in ARC along with a script to rotate the bottom servo. In functionality your radar would sweep right to left facing forward. The bottom servo would turn the radar around and the radar could sweep back left to right. Or you could simply turn the robot around so it could get a 360 degree view that way. I could have swore at one time servo city sold a servo that rotated nearly 360 degrees but it was not continuous rotation, it was a stand servo. But I can't find it now.

Jayutmb · Answer

Thx guys! I will try the back to back and see how that goes

DJ Sures · Answer

As everyone said - Standard Servos have a sensor to know their position. Continuous Rotation Servos do not have a sensor and operate more like a motor + gearbox. Here how a servo works: Click for tutorial Here's the video but I do recommend clicking to read more

rgordon · Answer

There are also servos called Sail Winch Servos that can rotate 3 and 1/2 turns. Check out Robot Market Place.com The HS-785HB sail winch servo with it's large drum wheel has 3 1/2 revolutions of travel for hauling in even the largest of sails. With its dual ball bearing supported output shaft the HS-785HB will provide years of reliable service. SPECS: Length: 2.32" Width: 1.14" Height: 1.96" Weight: 3.88 ounces Torque: 152.75 oz/in at 4.8V; 183 oz/in at 6V Speed: 1.68sec/360deg at 4.8V with no load; 1.4sec/360deg at 6V with no load Bearing Type: 1 Bearing and 1 Oilite Bushing Gear Type: Karbonite Motor Type: 3 Pole Ferrite There may be others who sell them for less. Google is your friend.

DJ Sures · Answer

interesting! I have never seen those sail winch servos before!

rb550f · Answer

I have an idea.You could a curved mirror to see 360 degree view like the new Dyson robot vac.

Jayutmb

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