SimplifiedPistonDynamics.ssc

component PistonDynamics
    % Reduced order pneumatic model
    % First-order plus deadtime damper piston model

parameters
    Fe_max = {282, 'N'}; % Extend force 324N
    Fr_max = {230, 'N'}; % Retract force 260N
    cu = {25, 'N*s/m'}; % Unactuated damping
    cd = {59, 'N*s/m'}; % Double extending damping
    ce = {97, 'N*s/m'}; % Extending damping
    cr = {84, 'N*s/m'}; % Retracting damping
    tau_min = {8, 'ms'}; % Time constant
    tau_max = {24, 'ms'}; % Time constant
    dead_time = {6, 'ms'}; % Dead-time
    stroke = {70, 'mm'}; % Stroke
end

variables
    Fe = {0, 'N'};
    Fr = {0, 'N'};
end

inputs
    ue = {0, '1' } % ue:left
    ur = {0, '1' } % ur:left
    p = {0, 'm'} % p:left
    v = {0, 'm/s' } % v:left
end

outputs
    F = {0, 'N' } % F:right
end

intermediates
    ue_d = delay(ue, dead_time);
    ur_d = delay(ur, dead_time);
    c = ce*ue_d*(1-ur_d) + cr*ur_d*(1-ue_d) + cd*ue_d*ur_d + cu*(1-ue_d-ur_d+ue_d*ur_d); % Damping
    pe = p;
    pr = stroke - p;
    m = (tau_max-tau_min)/stroke;
end

equations
    Fe == ue_d*Fe_max - (m*pe+tau_min)*Fe.der;
    Fr == ur_d*Fr_max - (m*pr+tau_min)*Fr.der;
%     Fe == ue_d*Fe_max - (tau_min)*Fe.der;
%     Fr == ur_d*Fr_max - (tau_min)*Fr.der;
    F == Fe - Fr - v*c;
end

end