Hi all,
I was reading about this servo actuator and was wondering if someone could please help with a couple of questions: pololu.com/catalog/product/501
Will this lift a few grams and accurately keep its position when powered off? (whilst holding the load). If it is not suitable for this purpose then could anyone please recommend something that might do the job?
Can these be directly connected to an arduino without suffering from jitter or is a special servo controller needed?
We list the stall torque under the Specifications tab on the product page for that servo. Using the stall torque you should be able to determine if that servo will be able to lift your load. This blog post on force and torque has more details on how to do that.
Once the power is removed from the servo, the only thing holding the servo in position is the internal friction of the servo. If that internal friction is not enough to hold your load in place, the servo would need to be powered to hold its position.
You can control a servo directly from an Arduino without any special servo controller, but the Arduino will have more jitter than a dedicated servo controller like our Maestro servo controllers.
Hi,
Thanks for your help, I checked the stall torque and worked out that it should be fine to lift the load.
If I use a maestro controller like you suggested (connected to Arduino) and keep the power on, then would it be accurate enough to hold it’s position within a millimeter of movement?
The idea is that I would use 4 of these to lift a small piece of glass (one at each corner) and keep it in position for 2-3 hours or more.
Could you also please tell me the approximate power consumption of one of these for about an hour, I couldn’t figure it out from the datasheet.
Thanks!
Regarding my previous post, I just realised that a digital servo may be a better way to go.
Could you please tell me if your ‘PowerHD’ range of micro servos would be accurate enough to hold their position when powered without moving (within 0.5 mm) if combined with a Maestro controller (The load would be well under the maximum).
For example: pololu.com/catalog/product/1047
(or can you recommend another servo - the servo weight is not important but accuracy is)
Also, how long can such servos hold their position safely without overheating etc? (minutes? hours? or days?)
When talking about RC servos, which have rotational movement, it is not very useful to specify an accuracy in a linear distance like millimeters. The distance in millimeters that your load moves will be dependent on other things in your system like the length of your lever arm. Instead the accuracy would be specified in angular units like degrees.
If you are worried about accuracy, then choosing to use the Maestro over just the Arduino (like it seems you have) is a good choice. When using the Maestro, the accuracy is almost always going to be limited by the servo itself, rather than the Maestro. Unfortunately, we do not have the accuracy characterized for our servos. To find out what the accuracy is for a servo, you would probably have to try it.
In regards to power consumption and how long the servo will hold its position, it will depend on your specific servo and system. However, if the torque needed to support your load is only a small fraction of the stall torque, I would not expect the servo to overheat.
