C1986
Mechanical
- Feb 14, 2011
- 1
Hello all,
I'm building a dynamical model of an exoskeleton. To determine the inertial properties Solid Works is used (version 2010).
If I look at the output in the mass properties section, something strange happens to my opinion.
If the rotation matrix is pre- and postmultiplied with the diagonal inertia matrix(Equation used: Iout = inv(R)*Iinert*R
), the solution does not correspond with the other output (numbers are correct but minus signs are wrong). An example is included below.
Can somebody help me?
Mass properties of selected components
Output coordinate System: Coordinate System4
The center of mass and the moments of inertia are output in the coordinate system of 100_Exoskeleton-without motors-update_20sim_07022011
Mass = 146.3293 grams
Volume = 50645.2787 cubic millimeters
Surface area = 23236.8002 millimeters^2
Center of mass: ( millimeters )
X = -48.3769
Y = -0.8218
Z = 82.9338
Principal axes of inertia and principal moments of inertia: ( grams * square millimeters )
Taken at the center of mass:
R: Ix = (-0.6466, 0.0162, 0.7627) Iinert(diagonal matrix with Px,Py and Pz on diagonal)
x = 53372.2917
Iy = (0.7625, 0.0442, 0.6455) Py = 546886.0625
Iz = (-0.0233, 0.9989, -0.0409) Pz = 560232.1085
Moments of inertia: ( grams * square millimeters )
Taken at the center of mass and aligned with the output coordinate system. Iout
Lxx = 340561.7431 Lxy = -4846.6654 Lxz = -243381.0661
Lyx = -4846.6654 Lyy = 560073.6574 Lyz = 6627.9462
Lzx = -243381.0661 Lzy = 6627.9462 Lzz = 259855.0621
I'm building a dynamical model of an exoskeleton. To determine the inertial properties Solid Works is used (version 2010).
If I look at the output in the mass properties section, something strange happens to my opinion.
If the rotation matrix is pre- and postmultiplied with the diagonal inertia matrix(Equation used: Iout = inv(R)*Iinert*R
), the solution does not correspond with the other output (numbers are correct but minus signs are wrong). An example is included below.
Can somebody help me?
Mass properties of selected components
Output coordinate System: Coordinate System4
The center of mass and the moments of inertia are output in the coordinate system of 100_Exoskeleton-without motors-update_20sim_07022011
Mass = 146.3293 grams
Volume = 50645.2787 cubic millimeters
Surface area = 23236.8002 millimeters^2
Center of mass: ( millimeters )
X = -48.3769
Y = -0.8218
Z = 82.9338
Principal axes of inertia and principal moments of inertia: ( grams * square millimeters )
Taken at the center of mass:
R: Ix = (-0.6466, 0.0162, 0.7627) Iinert(diagonal matrix with Px,Py and Pz on diagonal)
x = 53372.2917Iy = (0.7625, 0.0442, 0.6455) Py = 546886.0625
Iz = (-0.0233, 0.9989, -0.0409) Pz = 560232.1085
Moments of inertia: ( grams * square millimeters )
Taken at the center of mass and aligned with the output coordinate system. Iout
Lxx = 340561.7431 Lxy = -4846.6654 Lxz = -243381.0661
Lyx = -4846.6654 Lyy = 560073.6574 Lyz = 6627.9462
Lzx = -243381.0661 Lzy = 6627.9462 Lzz = 259855.0621
