Description
A rotation q=f(s) provided from a rotation sample, continuously updated by the user, behaving as a ZOH (zero order hold) of FOH (first order).
You must keep the setpoint q updated via multiple calls to SetSetpoint(), for example calling SetSetpoint() at each timestep in the simulation loop. It is assumed that one will later evaluate Get_q(), Get_w_loc() etc. in close vicinity of the setpoint (setpoint history is not saved), preferably ecactly at the same s, but in vicinity of s there will be extrapolation (after last s) and interpolation (before last s) according to: If in ZOH mode: rotation q will persist indefinitely until next call, angular velocity and angular acceleration will be zero. If in FOH mode: rotation q will interpolate linearly from the previous value, angular velocity will be constant, angular acceleration will be zero. Default: uses FOH mode. Use SetMode() to change it.
#include <ChFunctionRotation_setpoint.h>
Public Types  
enum  eChSetpointMode { ZOH, FOH, OVERRIDE } 
Type of setpoint interpolation/extrapolation  zero order hold, first order hold, etc. More...  
Public Member Functions  
ChFunctionRotation_setpoint (const ChFunctionRotation_setpoint &other)  
virtual ChFunctionRotation_setpoint *  Clone () const override 
"Virtual" copy constructor.  
void  SetMode (eChSetpointMode mmode) 
Sets the extrapolation/interpolation mode.  
eChSetpointMode  GetMode () 
Gets the extrapolation/interpolation mode.  
void  Reset (double ms=0) 
Use this to go back to s=0 (the SetSetpoint() function works only if called at increasing s values)  
virtual void  SetSetpoint (ChQuaternion<> q_setpoint, double s) 
Set the rotation setpoint, and compute its derivatives (angular speed, angular acceleration) automatically by backward differentiation (only if s is called at increasing small steps, most often s is time). More...  
virtual void  SetSetpointAndDerivatives (ChQuaternion<> q_setpoint, ChVector<> w_loc_setpoint, ChVector<> a_loc_setpoint) 
Set the setpoint, and also its derivatives (angular velocity, angular acceleration). More...  
virtual ChQuaternion  Get_q (double s) const override 
Return the q value of the function, at s, as q=f(s).  
virtual ChVector  Get_w_loc (double s) const override 
Return the derivative of the rotation function, at s, expressed as angular velocity w in local frame.  
virtual ChVector  Get_a_loc (double s) const override 
Return the derivative of the rotation function, at s, expressed as angular acceleration in local frame.  
virtual void  ArchiveOut (ChArchiveOut &marchive) override 
Method to allow serialization of transient data to archives.  
virtual void  ArchiveIn (ChArchiveIn &marchive) override 
Method to allow deserialization of transient data from archives.  
Public Member Functions inherited from chrono::ChFunctionRotation  
ChFunctionRotation (const ChFunctionRotation &other)  
virtual void  Estimate_s_domain (double &smin, double &smax) const 
Return an estimate of the domain of the function argument. More...  
virtual void  Update (double t) 
Update could be implemented by children classes, ex. to launch callbacks.  
Member Enumeration Documentation
◆ eChSetpointMode
Type of setpoint interpolation/extrapolation  zero order hold, first order hold, etc.
Enumerator  

ZOH  Zero Order Hold: q constant, w = a = 0 in neighbour of setpoint s. 
FOH  First Order Hold: q linear, w constant, a = 0 in neighbour of setpoint s. 
OVERRIDE  p, w, a are set via SetSetpointAndDerivatives() and will be considered constant in Get_q(s) regardless of s until next SetSetpointAndDerivatives() 
Member Function Documentation
◆ SetSetpoint()

virtual 
Set the rotation setpoint, and compute its derivatives (angular speed, angular acceleration) automatically by backward differentiation (only if s is called at increasing small steps, most often s is time).
Note: each time must be called with increasing s so that internally it add sthe 'new' setpoint and scrolls the previous samples for computing extrapolation/interpolation, but if called multiple times with exactly the same s value, the buffer of past samples is not scrolled: it just recompute setpoint and derivatives according to the 'updated' setpoint. If in ZOH mode: rotation q will persist indefinitely until next call, angular velocity and angular acceleration will be zero. If in FOH mode: rotation q will interpolate linearly from the previous value, angular velocity will be constant, angular acceleration will be zero.
◆ SetSetpointAndDerivatives()

inlinevirtual 
Set the setpoint, and also its derivatives (angular velocity, angular acceleration).
Moreover, changes the mode to eChSetpointMode::OVERRIDE, so all values will persist indefinitely until next call, that is multiple calls to Get_q(s) Get_w_loc() etc. will give same results (non interpolated) regardless of s.
The documentation for this class was generated from the following files:
 /builds/uwsbel/chrono/src/chrono/motion_functions/ChFunctionRotation_setpoint.h
 /builds/uwsbel/chrono/src/chrono/motion_functions/ChFunctionRotation_setpoint.cpp