Hello, I'm learning Sympy and trying to replicate a solution for the Euler pitch and roll angles as described in a well-known Application Note:
https://cache.freescale.com/files/sensors/doc/app_note/AN3461.pdf In particular, Equations 24 through 26. Here's the set up matching the reference frame used in the note. import sympy as sy def x_rotation(angle): return sy.Matrix([[1, 0, 0], [0, sy.cos(angle), sy.sin(angle)], [0, -sy.sin(angle), sy.cos(angle)]]) def y_rotation(angle): return sy.Matrix([[sy.cos(angle), 0, -sy.sin(angle)], [0, 1, 0], [sy.sin(angle), 0, sy.cos(angle)]]) def z_rotation(angle): return sy.Matrix([[sy.cos(angle), sy.sin(angle), 0], [-sy.sin(angle), sy.cos(angle), 0], [0, 0, 1]]) phi, theta, psi = sy.symbols("\\phi, \\theta, \\psi") x, y, z, g = sy.symbols("x, y, z, g") g_v = sy.Matrix([[0, 0, g]]) # gravity vector acc = sy.Matrix([[x, y, z]]) # acceleration vector I can certainly reproduce the referred rotation matrix in Eq 8 (`tilt_0' below), with a slight modification to my convention of post-multiplying a row vector by the rotation matrix: xyz_mat = (x_rotation(phi) * y_rotation(theta) * z_rotation(psi)) tilt_0 = g_v.subs(g, 1) * xyz_mat.T However, solving for pitch angle `theta' doesn't give the same result as the paper: In [10]: sy.solve(acc - tilt_0, phi) Out[10]: [(pi - asin(y/cos(\theta)),), (asin(y/cos(\theta)),)] What am I missing in this derivation? -- Seb -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/2d2b2cda-e448-4703-9cd6-a1dc13551ae4%40googlegroups.com.
