Added identification data and scripts from students

data/students/scripts/ident_nonlinear_model.m

+% Run nonlinear model identification
+
+clear variables;
+
+load_ident_data;
+
+idd_to_use = merge(idd_longsweep, idd_sweep2, idd_forcesweep, idd_forcesweep2, idd_forcestep, idd_faststep);
+
+
+% see the as_model_nl.m file for explanation of parameters
+i_ks = 990.38;
+i_ku = 2259.4;
+i_r  = 1.8947;
+i_bs = 1.4388;
+i_bu = 2.7914;
+i_fs = 0.52346;
+i_fu = 0.45989;
+i_gf = 0.7386;
+
+
+i_vars = [i_ks, i_ku, i_r, i_bs, i_bu, i_fs, i_fu, i_gf];
+model = idnlgrey('as_model_nl', [2 2 4], i_vars);
+model.SimulationOptions.Solver = 'ode4';
+model.SimulationOptions.FixedStep = idd_to_use.Ts{1};
+model.InputName = {'road', 'actuator'};
+model.InputUnit = {'m', 'N'};
+model.OutputName = {'zs', 'zus'};
+model.OutputUnit = {'m', 'm'};
+
+
+opts = nlgreyestOptions('Display', 'on');
+opts.SearchOptions.MaxIterations = 50;
+
+model_est = nlgreyest(idd_to_use, model, opts);
+% see model_est.Parameters.Value

data/students/scripts/load_ident_data.m

+% Load identification experiments into iddata objects
+
+% road sweeps
+idd_sweep       = load_road_experiment("../data/road_sweep_normal.mat");
+idd_sweep2      = load_road_experiment("../data/road_sweep_normal_2.mat");
+idd_lfsweep     = load_road_experiment("../data/road_sweep_lf.mat");
+idd_longsweep   = load_road_experiment("../data/road_sweep_long.mat");
+idd_hurak       = load_road_experiment("../../measured_and_simulated_open_loop_responses.mat");
+
+% road steps
+idd_slowstep    = load_road_experiment("../data/road_step_slow.mat");
+idd_faststep    = load_road_experiment("../data/road_step_fast.mat");
+
+% actuator sweeps
+idd_forcesweep  = load_actuator_experiment("../data/actuator_sweep.mat");
+idd_forcesweep2 = load_actuator_experiment("../data/actuator_sweep_lf_longer_v2.mat");
+
+% actuator steps
+idd_forcestep   = load_actuator_experiment("../data/actuator_step.mat");
+
+
+function idd = load_road_experiment(filename)
+    mat_file = load(filename);
+
+    Ts = mat_file.measured_pos_ol_response.time(2) - mat_file.measured_pos_ol_response.time(1);
+    padding = 1000;
+
+    zr   = mat_file.measured_pos_ol_response.signals.values(:,1);
+    zus  = mat_file.measured_pos_ol_response.signals.values(:,2);
+    zs   = mat_file.measured_pos_ol_response.signals.values(:,3);
+    full_y = [
+        zeros(padding, 2);
+        [zs, zus]
+    ];
+    full_u = [
+        zeros(padding, 2);
+        [zr, zeros(length(zr), 1)]
+    ];
+    idd = create_idd(full_y, full_u, Ts);
+end
+
+function idd = load_actuator_experiment(filename)
+    mat_file = load(filename);
+
+    Ts = mat_file.measured_pos_ol_response.time(2) - mat_file.measured_pos_ol_response.time(1);
+    padding = 1000;
+
+    zus  = mat_file.measured_pos_ol_response.signals.values(:,2);
+    zs   = mat_file.measured_pos_ol_response.signals.values(:,3);
+    full_y = [
+        zeros(padding, 2);
+        [zs, zus]
+    ];
+    full_u = [
+        zeros(padding, 2);
+        mat_file.control_signal.signals.values
+    ];
+    idd = create_idd(full_y, full_u, Ts);
+end
+
+function idd = create_idd(full_y, full_u, Ts)
+    idd = iddata(full_y, full_u, Ts);
+    idd.InputName = {'road', 'actuator'};
+    idd.InputUnit = {'m', 'N'};
+    idd.OutputName = {'zs', 'zus'};
+    idd.OutputUnit = {'m', 'm'};
+end