user_ExtForces module¶

Module for defining user function required to compute external forces.

user_ExtForces.user_ExtForces(PxF, RxF, VxF, OMxF, AxF, OMPxF, mbs_data, tsim, ixF)¶

Compute an user-specified external force.

Parameters

PxF (numpy.ndarray) – Position vector (index starting at 1) of the force sensor expressed in the inertial frame: PxF[1:4] = [P_x, P_y, P_z]
RxF (numpy.ndarray) – Rotation matrix (index starting at 1) from the inertial frame to the force sensor frame: Frame_sensor = RxF[1:4,1:4] * Frame_inertial
VxF (numpy.ndarray) – Velocity vector (index starting at 1) of the force sensor expressed in the inertial frame: VxF[1:4] = [V_x, V_y, V_z]
OMxF (numpy.ndarray) – Angular velocity vector (index starting at 1) of the force sensor expressed in the inertial frame: OMxF[1:4] = [OM_x, OM_y, OM_z]
AxF (numpy.ndarray) – Acceleration vector (index starting at 1) of the force sensor expressed in the inertial frame: AxF[1:4] = [A_x, A_y, A_z]
OMPxF (numpy.ndarray) – Angular acceleration vector (index starting at 1) of the force sensor expressed in the inertial frame: OMPxF[1:4] = [OMP_x, OMP_y, OMP_z]
mbs_data (MBsysPy.MbsData) – The multibody system associated to this computation.
tsim (float) – The current time of the simulation.
ixF (int) – The ID identifying the computed force sensor.

Notes

For 1D numpy.ndarray with index starting at 1, the first index (array[0]) must not be modified. The first index to be filled is array[1].

For 2D numpy.ndarray with index starting at 1, the first row (mat[0, :]) and line (mat[:,0]) must not be modified. The subarray to be filled is mat[1:, 1:].

Returns: Swr – An array of length 10 equal to [0., Fx, Fy, Fz, Mx, My, Mz, dxF]. F_# are the forces components expressed in inertial frame. M_# are the torques components expressed in inertial frame. dxF is an array of length 3 containing the component of the forces/torque application point expressed in the BODY-FIXED frame. This array is a specific line of MbsData.SWr.
Return type: numpy.ndarray