14-Alexandrite

Question

Non linear speed control

Forum|Forum|4 years ago
January 31, 2022
2 replies
6712 views

Hi community , Once again I call on you .

my problem:

I have a mechanism with a non-linear movement

in input, I have a linear displacement, and in output I have an angular displacement

this displacement follows a behavior curve

I want to drive the input with a motor, so here is my problem.

I want to find a max speed value of motor to reach a given angular position. But also that time is linear

that is to say, if I want to go from 0 degrees to 60 degrees (for example) what will be my lowest linear displacement time (constant speed value at output), and what will be my motor control curve

the solution I found is cut the curve with linear parts,but I don't really like it because it's DIY

I don't see the way to get there, maybe with the derivative

If someone has an idea

1_linear-and-angular-speed.zip

Mechanical_Engineering

W

Werner_E

25-Diamond I

I don't see your attempt in the file you sent.

As far as I understand you are looking for a function

alpha -> speed in rev/s

Can you show the calculations necessary and the result for one or two example angles?

X

XDN

Author

14-Alexandrite

I'm having trouble explaining myself because I don't speak the language well.

example

if i want to move Alpha =60deg ( row 61 in alpha matrix)

the imput stroke is 32.355mm (row 61 in s matrix)

For 1 motor rev the imput stroke is :0.069mm

Capture d’écran 2022-01-31 130442.jpg Finally, i need to make 32.355mm

and so my motor must do 32.355/0.069 = 468.913 rev

max motor rev speed :0.287 rev/s but is non linear

if i cut the curve, and if that I admit a linear part from 0deg to 10deg

for 10 deg , imput is 2.682mm

2.682/0.069=38.87rev

time is :135.436s for travel 0 to 10deg

and now i assume my curve is linear from 10deg to 60deg

imput stroke 60deg =32.355mm

imput stroke 10deg = 2.682mm

32.355-2.682 = 29.673mm

29.673/0.069= 430.043rev

430.043/0.287=1498s

I don't know if I'm clear, but I want to come to this:

find max speed motor for each target value (row of alpha matrix) for a linear travel time

i want to move 0deg to 60deg with lineartravel, for this I can see that my motor must turn slowly at the beginning, then as quickly as possible at the end

the max speed end is 0.287rev/s so it is this value which is measured to evaluate the speeds at small angles

sorry for these confusing explanations, I think there may be a way with the derivative, but I can't find anything

W

Werner_E

25-Diamond I

> for one rev, the nut travel 2mm thanks to the helical connection

One revolution of the screw, after the gear box, not one revolution of the driving motor, right?

> v.vis_vss33 = 0.575 mm/s mean the nut velocity translation

Still unclear to me. Is this a fictive velocity of the the nut if there would be no gear box and the real nut velocity is 0,02 mm/s as shown??

Anyway, here are my thoughts so far and I in no way claim that I am on the correct way with them. At least its an explanation why I thought it might be helpful to have a function alpha(s), either by interpolation or by regression. Of course as you probably know all dimensions of your mechanics, you may also derive the exact function alpha(s) using basic geometry.