Hi everyone,
I'm designing a Celiometer <> it's a IR sensor which permiss clouds' temperature measurement to estimate their altitude.
I need to control a deflector in rotation to clean my sensor's head.
I need a waterproof solution but I don't know what will be the best actuator.
I imagined on continuous rotation with some location switch but this reduce deeply the list of choices.
Is there some one to advice me?
A diagram of the mechanical arrangement you want to implement would be very useful.
You don't say how big is the area to be cleaned
or how frequently it needs to be cleaned
or what will be doing the cleaning (a brush? a squeegee? what?)
or what forces are required to move the cleaning device.
If a servo is suitable then it is a very convenient option.
Maybe a simple geared DC motor would be adequate? It would have the advantage of consuming no power when not being used.
You have provided no information to support the idea that the precision of a stepper motor would be useful. And stepper motors are very inefficient.
...R
I don't know what you need...
Windshield wipers on a car use a DC motor. A DC motor (possibly geared-down or reduced with pulleys) and one or more position sensors might be appropriate for you too.
Stepper motors & servos are both "positional" motors. i.e. If you want to move a certain (variable/programmable) distance, they might be the solution. I don't think you need that... I think maybe you only need one or two end-points.
Servos are angular motors, and they can't rotate 360 degrees. Steppers can rotate more than 360 degrees, but they step 1.8 degrees at a time, so they are less precise (unless they are geared-down). A stepper also needs one or two home/position sensors so the software knows where it is when it starts counting steps. If a stepper motor looses a step, the software doesn't know 'till it gets back to the home position. A servo always knows where it is and where it's supposed to be and will self-correct.
Oh, servos have a driver circuit built-in so you only have to provide power and a position signal. DC & stepper motors require a driver circuit.
OK,
this is some additional features.
The deflector should turn each 180°, to assume a right position I'll place 2 switches.
A clean up action could be request by the sequence if the IR measurement indicate bad consistency (in due of water or condensation over the sensor's head)
I imagined an anti-icing function and in this case I'll have to manage frequent rotations to avoid ice.
Under the rain I'll need also a sequence of clean up but limited with the consistency test (for ex, after a rotation, we test the IR response during 10s, if it's again bad we hold the max cycle rotation because, the rain is probably to strong and we can't do anything more)
The surface to clean is a germanium disc for IR transparency (diameter:25mm)
You could find a 3d pix in attachement.
Today the sensor is running and covered with a fixe deflector. I'm just at the beginning but I would like to remove deflector to place a bearing with the servo an the rotating new deflector.
I can't figure from the diagrams what part needs to be kept clean. I'm guessing it is the little black spot in the first image.
I would be very tempted to put a long arm on a servo and make it into a miniature windscreen wiper.
...R
