Compare friction models

This simulation compares a standard friction model with a bristle friction model.

Contents

%--------------------------------------------------------------------------
%   Copyright (c) 2015 Princeton Satellite Systems, Inc.
%   All rights reserved.
%--------------------------------------------------------------------------
%   Since 2016.1
%--------------------------------------------------------------------------

Default data

d = RHSFriction;

% We have just one state
d.friction.cDampingRWA        = 4.0e-5;
d.friction.torqueCoulombRWA   = 2.45e-3;
d.friction.torqueStictionRWA  = 3e-3;
d.friction.alphaStictionRWA   = 8;

% Initial state
x   = [-4;-4;0];

% Motor torque
d.torque	= 0.008;

% Time
dT    = 0.002;
tEnd  = 1;
nSim  = ceil(tEnd/dT);

Simulation

xP        = zeros(5,nSim);
for k = 1:nSim
  [~,fS,fB]	= RHSFriction(x, 0, d );
  xP(:,k)   = [x;fS;fB];
  x         = RK4( 'RHSFriction', x, dT, 0, d );
end

% Plotting
[t,tL]	= TimeLabl((0:nSim-1)*dT);
yL      = {'\omega', 'bristle state','friction'};
Plot2D( t, xP, tL, yL, 'Friction Comparison','lin',{'[1 2]' '3' '[4 5]'})
legend('Standard','Bristle','location','southeast');

Simulation

Initial state

x         = [-0.25;-0.25;0];
tEnd      = 0.25;
nSim      = ceil(tEnd/dT);
d.friction.useSigmoid = 1;
d.friction.betaSigmoid = 300;

% Motor torque
d.torque	= 0.001;


xP        = zeros(5,nSim);
for k = 1:nSim
  [~,fS,fB]	= RHSFriction(x, 0, d );
  xP(:,k)   = [x;fS;fB];
  x         = RK4( 'RHSFriction', x, dT, 0, d );
end

% Plotting
[t,tL]	= TimeLabl((0:nSim-1)*dT);
yL      = {'\omega', 'bristle state','friction'};
Plot2D( t, xP, tL, yL, 'Friction Comparison','lin',{'[1 2]' '3' '[4 5]'})
legend('Standard','Bristle','location','southeast');


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Published with MATLAB® R2019a