Error using predict.
2 views (last 30 days)
Show older comments
I try to run the program based on "Modeling an Industrial Robot Arm" but I got error using predict (line 112). Is there any method to solve this problem?
FileName = 'robotarm_c'; % File describing the model structure.
Order = [1 1 5]; % Model orders [ny nu nx].
Parameters = [ 0.00986346744839 0.74302635727901 ...
3.98628540790595 3.24015074090438 ...
0.79943497008153 0.03291699877416 ...
0.17910964111956 0.61206166914114 ...
20.59269827430799 0.00000000000000 ...
0.06241814047290 20.23072060978318 ...
0.00987527995798]'; % Initial parameter vector.
InitialStates = zeros(5, 1); % Initial states.
Ts = 0; % Time-continuous system.
nlgr = idnlgrey(FileName, Order, Parameters, InitialStates, Ts, ...
'Name', 'Robot arm', ...
'InputName', 'Applied motor torque', ...
'InputUnit', 'Nm', ...
'OutputName', 'Angular velocity of motor', ...
'OutputUnit', 'rad/s', ...
'TimeUnit', 's');
nlgr = setinit(nlgr, 'Name', {'Angular position difference between the motor and the gear-box' ...
'Angular position difference between the gear-box and the arm' ...
'Angular velocity of motor' ...
'Angular velocity of gear-box' ...
'Angular velocity of robot arm'}');
nlgr = setinit(nlgr, 'Unit', {'rad' 'rad' 'rad/s' 'rad/s' 'rad/s'});
nlgr = setpar(nlgr, 'Name', {'Fv : Viscous friction coefficient' ... % 1.
'Fc : Coulomb friction coefficient' ... % 2.
'Fcs : Striebeck friction coefficient' ... % 3.
'alpha: Striebeck smoothness coefficient' ... % 4.
'beta : Friction smoothness coefficient' ... % 5.
'J : Total moment of inertia' ... % 6.
'a_m : Motor moment of inertia scale factor' ... % 7.
'a_g : Gear-box moment of inertia scale factor' ... % 8.
'k_g1 : Gear-box stiffness parameter 1' ... % 9.
'k_g3 : Gear-box stiffness parameter 3' ... % 10.
'd_g : Gear-box damping parameter' ... % 11.
'k_a : Arm structure stiffness parameter' ... % 12.
'd_a : Arm structure damping parameter' ... % 13.
});
nlgr = setpar(nlgr, 'Minimum', num2cell(zeros(size(nlgr, 'np'), 1))); % All parameters >= 0!
for parno = 1:6 % Fix the first six parameters.
nlgr.Parameters(parno).Fixed = true;
end
present(nlgr);
load(fullfile(matlabroot, 'toolbox', 'ident', 'iddemos', 'data', 'robotarmdata'));
z = iddata({ye yv1 yv2 yv3}, {ue uv1 uv2 uv3}, 0.5e-3, 'Name', 'Robot arm');
z.InputName = 'Applied motor torque';
z.InputUnit = 'Nm';
z.OutputName = 'Angular velocity of motor';
z.OutputUnit = 'rad/s';
z.ExperimentName = {'Estimation' 'Validation 1' 'Validation 2' 'Validation 3'};
z.Tstart = 0;
z.TimeUnit = 's';
present(z);
figure('Name', [z.Name ': input-output data'],...
'DefaultAxesTitleFontSizeMultiplier',1,...
'DefaultAxesTitleFontWeight','normal',...
'Position',[100 100 900 600]);
for i = 1:z.Ne
zi = getexp(z, i);
subplot(z.Ne, 2, 2*i-1); % Input.
plot(zi.u);
title([z.ExperimentName{i} ': ' zi.InputName{1}],'FontWeight','normal');
if (i < z.Ne)
xlabel('');
else
xlabel([z.Domain ' (' zi.TimeUnit ')']);
end
subplot(z.Ne, 2, 2*i); % Output.
plot(zi.y);
title([z.ExperimentName{i} ': ' zi.OutputName{1}],'FontWeight','normal');
if (i < z.Ne)
xlabel('');
else
xlabel([z.Domain ' (' zi.TimeUnit ')']);
end
end
zred = z(1:round(zi.N/10));
nlgr = setinit(nlgr, 'Fixed', {true true false false false});
X0 = nlgr.InitialStates;
[X0.Value] = deal(zeros(1, 4), zeros(1, 4), [ye(1) yv1(1) yv2(1) yv3(1)], ...
[ye(1) yv1(1) yv2(1) yv3(1)], [ye(1) yv1(1) yv2(1) yv3(1)]);
[~, X0init] = predict(zred, nlgr, [], X0);
nlgr = setinit(nlgr, 'Value', num2cell(X0init(:, 1)));
clf
compare(z, nlgr, [], compareOptions('InitialCondition', X0init));
3 Comments
Answers (0)
See Also
Categories
Find more on Robotics in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!