Path: SC/Dynamics

% Momentum bias spacecraft model
 Computes the state space description of a momentum bias spacecraft where the
 internal momentum is fixed. If dT is not input it returns the continuous time
 plant. If dT is input it returns the discrete time plant. In either case, the
 plant is linearized about wo. The state vector is


 Where the state vector is with respect to the rotating frame
 defined by wo.

 The outputs are the angles, i.e. the first three elements in the
 state vector.

 If h and wo are not in the same direction or inr is not diagonal,
 dxdt will be nonzero and you will get constant disturbance torques.

 If only one output is specified it gives the right hand side 
 of the nonlinear dynamical equations of motion. You need to use
 the kinematics routines to get the nonlinear kinematics equations.

   [a,b,c,d,dxdt] = MBModel(inr,h,wo)
   [a,b,c,d,dxdt] = MBModel(inr,h,wo,dT)
   [wDot]         = MBModel(inr,h,w,torque)

   inr           (3,3)  Inertia matrix
   h             (3,1)  Internal momentum vector
   wo            (3,1)  Orbit rate vector
   dT            (*,1)  Sampling period (1) or torque vector (3)

   a             (6,6)  Plant matrix
   b             (6,3)  Input matrix
   c             (3,6)  Output matrix
   d             (3,3)  Feedthrough matrix
   dxdt          (3,1)  Steady state derivative


   wDot          (3,1)  State derivative



Common: Control/C2DZOH
Math: Linear/SkewSymm

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