Quote:
Originally Posted by Mr V
The gear ratio needed depends on what is happening after the transmission. What is the diameter of the drum or drive sprocket?
Define what you mean by lift 6 totes plus 1 bin in 3-4 sec, how far do you want to lift it in that time? Once you have created a 6T + 1C stack you only need to lift it a little more than 2" to place it on the scoring platform. That should be able to be done in a fraction of a second. So how are you creating that stack, ie what is the heaviest load and how far to you need to lift it and what is the highest distance you need to lift and how much is that weight.
Here is the JVN design calculator page. http://www.chiefdelphi.com/media/papers/2755? On the first tab copy the motor you wish to use and paste it into the linear motion tab motor fields.
You can then select the motors per trans, gear box efficiency (I use 10% per planetary stage), the amount of weight you wish to lift (don't forget the weight of the mechanism and a fudge factor to overcome the friction), the distance you want to lift the load and then play with gear ratios. For the planetary it is easiest to put 1 in for the drive and the ratio of the stage in the driven fields. For stages you are not using just put 1 in both fields. It is a good idea to make sure that the stall torque is significantly more than the load you want to lift in case the load "sticks". Personally I wouldn't design for less than 2X the actual weight.
Personally I'd recommend the Mini CIM or CIM for this application despite that it is more involved to mount. The 775 is a fan cooled motor so it doesn't like spinning slowly and really doesn't like being stalled. The CIM families on the other hand are much more tolerant of operating at slow speeds and being stalled. |
Agree!
We use a CIM motor last year for our winch and it performed well and tolerate stalling very well. The load we put on last year is way higher than this year's lift requirement. We did fried one CIM motor on our practice bot but that was only after practicing for 3 hours non stop. The motor was so hot we could fry an egg.
We use the JVN calculator to decide on the sprocket size and versaplanetary gear ratio for this year's lift. What we observe in real life is very close to what we predicted.