Demonstrate the use of the smooth friction model

------------------------------------------------------------------------- See also Plot2D, TimeLabl, RK4, FrictionSmooth -------------------------------------------------------------------------

Contents

------------------------------------------------------------------------- Copyright (c) 2003 Princeton Satellite Systems, Inc. All rights reserved. -------------------------------------------------------------------------

For an Honeywell HR2020 RWA from datasheet S61-7030-7.0-0

%----------------------------------------------------------
pMax       = 35; % W
wMax       = 6400*2*pi/60; % RPM to rad/sec
fViscous   = pMax/wMax; % From holding power
bViscous   = fViscous/wMax;

nSim       = 1000;
xPlot      = zeros(2,nSim);
clear d;
d.fCoulomb = 0.1*fViscous; % A guess
d.kCoulomb = 1;
d.fStatic  = 3*d.fCoulomb;
d.kStatic  = 10;
d.bViscous = bViscous;

fprintf('Viscous coefficient = %12.4f Nm/rad/s\n',d.bViscous)
fprintf('Coulomb friction    = %12.4f Nm\n',d.fCoulomb)
fprintf('Static friction     = %12.4f Nm\n',d.fStatic)

x          = 1;
dT         = 0.2;

Viscous coefficient =       0.0001 Nm/rad/s
Coulomb friction    =       0.0052 Nm
Static friction     =       0.0157 Nm

Simulation of the effect of friction

%-------------------------------------
for k = 1:nSim
  f          = FrictionSmooth(x,d);
  x          = RK4('FSRHS',x,dT,0,d);
  xPlot(:,k) = [x;f];
end

[t,xL] = TimeLabl((0:(nSim-1))*dT);

yL = ['Rate  (rad/s)';...
      'Friction (Nm)'];
Plot2D(t,xPlot,xL,yL, 'Smooth Friction Demo')

Friction as a function of rate

%-------------------------------
f2 = FrictionSmooth(linspace(-1,1),d);
Plot2D(linspace(-1,1),f2,'Rate (rad/s)','Friction (Nm)','Friction Curve' )


%--------------------------------------

Published with MATLAB® R2019a