scissor jack math

scissormath.txt

import math

### Input variables

# distance from end pin to center pin on scissor arm
c = 12
# minimum height, when arms are touching
a = 3

### calculated variables

# c^2
c2 = c ** 2
# maximum height
m = math.sqrt(c2 - (a ** 2))

### Utility functions

# transform Z position
# parameters:
#   z; requested Z position
# returns:
#   number of units motor must turn from lowest position

def z_scissor_transform(z):
    if ((z + a) > m):
        raise ValueError("Can't move here!")
    return (m - math.sqrt(c2 - ((z + a) ** 2)))

# get Z delta
# paramters:
#   cz; current Z position
#   dz; destination Z position
# returns:
#   number of units motor must turn to get from cz to dz. may be negative

def z_scissor_delta(cz, dz):
    return z2steps(dz) - z2steps(cz)