addController made error in calling Manager

[Thomas Uchida]

I checked the stateStorage.getColumnLabels. Since this labels start by "time" and name of state variables follows. Therefore, getitem(k) can work in this case.

Ah, sorry, I forgot that Time was included in the array of column labels.

[Hide Kimpara]

Hello Christopher,

I checked the simulation performance line by line.

You must call `initSystem()` before constructing the Manager:

Code: Select all

osimModel.initSystem();
simulationManager = Manager(osimModel);

I realized the call 'osimModel.initSystem();' made all state variables back to defaults. Even I updated state variables using osimModel.updCoordinateSet, initSystem changed them back to defaults defined in preexisting osim file.

When I call Manager() in C++ or MATLAB with OpenSim 3.3, I have never called secondary "initSystem". Why do we need to call it with OpenSim 4.0?
If we need 'InitSystem' before calling Manager(), can we call them in the beginning or earlier than any modification or updating variables?

my current MATLAB codes are attached below.

Thank you,
Hide

main_20171026.m

Code: Select all

% ----------------------------------------------------------------------- %
% main_YYYYMMDD.m
%
% Author: Hideyuki Kimpara, Worcester Polytechnic Institute
%
% This code uses the Matlab interface to the OpenSim API to run a trial
% to connect simulink simulator and OpenSim analysis. 
% This example borrows from other Matlab and C++ examples avaiable from
% the OpenSim project written by several people including, but not limited
% to: Brian Umberger and OpenSim team members at Stanford University.
% ----------------------------------------------------------------------- %
clearvars
clear

% Node and timing information
System_StartTim  = 0.00;
System_End_Time  = 000.30;
System_Frequency = fix(1000.);

kp = 10;
kv = 1;

if System_Frequency < 1
    System_Frequency = 1.;
end


System_timestep = 1./System_Frequency;

System_Num_step = fix((System_End_Time-System_StartTim)*System_Frequency);


% Import the OpenSim modeling classes
import org.opensim.modeling.*

% Create an OpenSim model from an OSIM file
Model_In = ['TwoLinkArmModel.osim'];
osimModel = Model(Model_In);

output_Dir = 'Result';

% Prepare temporary export model file for debug
fileoutpath = [Model_In(1:end-5),'_Monitor_01.osim'];


% Add Analyses to the model: ForceReporter and BodyKinematics 
aActuation = Actuation(osimModel);
aBodyKinematics = BodyKinematics(osimModel);
aForceReporter = ForceReporter(osimModel);
aJointReaction = JointReaction(osimModel);
aKinematics = Kinematics(osimModel);
aStatesReporter = StatesReporter(osimModel);
osimModel.addAnalysis(aActuation);
osimModel.addAnalysis(aBodyKinematics);
osimModel.addAnalysis(aForceReporter);
osimModel.addAnalysis(aJointReaction);
osimModel.addAnalysis(aKinematics);
osimModel.addAnalysis(aStatesReporter);


% Initialize the model (build the system and intialize the state)
osimState = osimModel.initSystem();

% Get the number of states from the model;
% in this case the number of controls equals the number of muscles

Num_Cent_Cnt = 2;
CentStruct = struct();
CentStruct.Number = Num_Cent_Cnt;
CentStruct.Cent_val_name = cell(1, Num_Cent_Cnt);
CentStruct.Cent_cor_name = cell(1, Num_Cent_Cnt);
CentStruct.Cent_act_name = cell(1, Num_Cent_Cnt);
CentStruct.ValAd = zeros(1, Num_Cent_Cnt);
CentStruct.Q_des = zeros(1, Num_Cent_Cnt);
CentStruct.U_des = zeros(1, Num_Cent_Cnt);
CentStruct.Q_ini = zeros(1, Num_Cent_Cnt);
CentStruct.U_ini = zeros(1, Num_Cent_Cnt);
CentStruct.ContV = zeros(1, Num_Cent_Cnt);
CentStruct.kp = kp * ones(1, Num_Cent_Cnt);
CentStruct.kv = kv * ones(1, Num_Cent_Cnt);

CentStruct.Cent_cor_name(1,1) = cell({'joint_1'});
CentStruct.Cent_cor_name(1,2) = cell({'joint_2'});
CentStruct.Cent_act_name(1,1) = cell({'joint_1_actuator'});
CentStruct.Cent_act_name(1,2) = cell({'joint_2_actuator'});

CentStruct.Q_des(1,1) =  80. * pi / 180.;
CentStruct.U_des(1,1) =  0.0 * pi / 180.;
CentStruct.Q_des(1,2) = -80. * pi / 180.;
CentStruct.U_des(1,2) =  0.0 * pi / 180.;

Control_Func.time = zeros(1, System_Num_step*2+1);
Control_Func.data = zeros(Num_Cent_Cnt, System_Num_step*2+1);
Control_Func.name = CentStruct.Cent_act_name;
Control_Func.time(1) = System_StartTim;
for i=1:System_Num_step
    Control_Func.time(i*2)   = System_StartTim + System_timestep * (i-1) + System_timestep*0.01;
    Control_Func.time(i*2+1) = System_StartTim + System_timestep * (i);
end




for i=1:Num_Cent_Cnt
    Coord = osimModel.getCoordinateSet().get(CentStruct.Cent_cor_name(1,i));
    CentStruct.Q_ini(1,i) = Coord.getValue(osimState);
    CentStruct.U_ini(1,i) = Coord.getSpeedValue(osimState);
    Coord.setValue(osimState, 0.0);
    Coord.setSpeedValue(osimState, 0.0);
end

% If I need to change initial joint angles, input values here.
CentStruct.Q_ini(1,1) = 90. * pi / 180.;
CentStruct.Q_ini(1,2) = 60. * pi / 180.;

% Solve difference of variable orders between osimModel and osimState.
osimModel.realizeVelocity(osimState);
for i=1:Num_Cent_Cnt
    Coord = osimModel.getCoordinateSet().get(CentStruct.Cent_cor_name(1,i));
    Coord.setValue(osimState, 1.);
    Coord.setSpeedValue(osimState, -8888.8);
    osimModel.realizeVelocity(osimState);
    tempQ = osimState.getQ;
    tempU = osimState.getU;
    for j=1:size(tempQ)
        if tempU.get(j-1) == -8888.8
            CentStruct.ValAd(1,i) = j;
            break;
        end
    end
    Coord.setValue(osimState, 0.0);
    Coord.setSpeedValue(osimState, 0.0);
    osimState.getQ
end

% Return initial state variables into osimModel.
for i=1:Num_Cent_Cnt
    Coord = osimModel.getCoordinateSet().get(CentStruct.Cent_cor_name(1,i));
    Coord.setValue ( osimState, CentStruct.Q_ini(1,i) );
    Coord.setSpeedValue ( osimState, CentStruct.U_ini(1,i) );
end

%# Set the initial states of the model
editableCoordSet = osimModel.updCoordinateSet();

% Arrange the initial guess by nodes and states
for i=1:Num_Cent_Cnt
    editableCoordSet.get(CentStruct.Cent_cor_name(1,i)).setValue(osimState, CentStruct.Q_ini(1,i));
    editableCoordSet.get(CentStruct.Cent_cor_name(1,i)).setSpeedValue(osimState, CentStruct.U_ini(1,i));
end


JointSet = osimModel.getJointSet();
CoordSet = osimModel.getCoordinateSet();
StateValNames      = osimModel.getStateVariableNames();

InitStruct = struct();
InitStruct.JointSet  = cell(JointSet.getSize,1);
InitStruct.CoordSet  = cell(CoordSet.getSize,1);
InitStruct.StateLabl = cell(StateValNames.getSize,1);
InitStruct.StateVals = zeros(StateValNames.getSize,1);

for i = 1:StateValNames.getSize
    InitStruct.StateLabl(i,1) = cell(StateValNames.getitem(i-1));
    SpString = split(InitStruct.StateLabl(i,1),'/');
    JointName = char(SpString(1));
    CoordName = char(SpString(2));
    ValueName = char(SpString(3));
    Coord = osimModel.getCoordinateSet().get(CoordName);
    if strcmp(ValueName, 'value')
        InitStruct.StateVals(i,1) = Coord.getValue(osimState);        
    else
        InitStruct.StateVals(i,1) = Coord.getSpeedValue(osimState);        
    end
end

for i = 1:CoordSet.getSize
    InitStruct.CoordSet(i,1) = cell(CoordSet.get(i-1));
end

for i = 1:JointSet.getSize
    InitStruct.JointSet(i,1) = cell(JointSet.get(i-1));
end





% Parameters to be passed in to the forward function
params.model  = osimModel;
params.state  = osimState;
params.CentSt = CentStruct;
params.Control = Control_Func;

stateStorage = aStatesReporter.getStatesStorage();

% start a timer
tic;

for i = 1:System_Num_step
    time_start = System_StartTim + System_timestep * (i-1);
    time_end = System_StartTim + System_timestep * (i);

    disp(['Cycle [' int2str(i) ']/[' int2str(System_Num_step) '] : Calculating from ' num2str(time_start) ' to ' num2str(time_end)]);

    ForwardOsimFunction_171026(time_start,time_end,params,InitStruct);


    % Use last state variables for next step initial states
    AA = stateStorage.getColumnLabels;
    AB = stateStorage.getLastStateVector().getData;
    for k=1:AB.getSize
        for j = 1:size(InitStruct.StateLabl,1)
           if (strcmp(InitStruct.StateLabl(j),AA.getitem(k)))
               InitStruct.StateVals(j) = AB.getitem(k-1);
           end
        end
    end
    disp(['state val [' num2str(AB.get(0)/pi*180.) '], [' num2str(AB.get(2)/pi*180.) ']  ' ]);
    disp('');

    clear AA AB;
    
end



% stop the timer
runtime = toc;
disp(['The runtime was ' num2str(runtime)]);



% Write out storage files containing the states and excitations
if isdir (output_Dir) == 0
    mkdir (output_Dir);
end
outputpath = ['.\' char(output_Dir) '\'];  % use current directory
bufferstamp = char(datetime,'yy_MM_dd-HH_mm');
osimModel.printControlStorage(['SimOut_',bufferstamp,'_excitations.sto']);

% Also write out the results of the analyses to storage files
aActuation.printResults(['SimOut_',bufferstamp],outputpath,0.01,'.sto');
aBodyKinematics.printResults(['SimOut_',bufferstamp],outputpath,0.01,'.sto');
aForceReporter.printResults(['SimOut_',bufferstamp],outputpath,0.01,'.sto');
aJointReaction.printResults(['SimOut_',bufferstamp],outputpath,0.01,'.sto');
aKinematics.printResults(['SimOut_',bufferstamp],outputpath,0.01,'.sto');
aStatesReporter.printResults(['SimOut_',bufferstamp],outputpath,0.01,'.sto');
aStatesReporter.printResults(['SimOut_',bufferstamp],'.\.',-1,'.sto');



% Reset the analyses so everything starts fresh for the next
% call to this function
aActuation.getForceStorage.reset(0);
aActuation.getPowerStorage.reset(0);
aActuation.getSpeedStorage.reset(0);
aBodyKinematics.getPositionStorage.reset(0);
aBodyKinematics.getVelocityStorage.reset(0);
aBodyKinematics.getAccelerationStorage.reset(0);
aForceReporter.getForceStorage.reset(0);
aKinematics.getAccelerationStorage.reset(0);
aKinematics.getPositionStorage.reset(0);
aKinematics.getVelocityStorage.reset(0);
aStatesReporter.getStatesStorage.reset(0);

ForwardOsimFunction_171026.m:

Code: Select all

function ForwardOsimFunction_171026(time_start,time_end,ExtraPar,InitStruct)
% ----------------------------------------------------------------------- %
% ForwardOsimFunction_YYMMDD.m
%
% Author: Hideyuki Kimpara, Worcester Polytechnic Institute
%
% This code uses the Matlab interface to the OpenSim API to run a trial
% to connect simulink simulator and OpenSim analysis. 
% This example borrows from other Matlab and C++ examples avaiable from
% the OpenSim project written by several people including, but not limited
% to: Brian Umberger and OpenSim team members at Stanford University.
% ----------------------------------------------------------------------- %

    % Import the OpenSim modeling classes
    import org.opensim.modeling.*

    % Get reference to the model
    osimModel       = ExtraPar.model;
%     s               = ExtraPar.state;
    CentStruct      = ExtraPar.CentSt;
    Control_Func       = ExtraPar.Control;



    % Check to see if model state is initialized by checking size
    if(osimModel.getWorkingState().getNY() == 0)
       s = osimModel.initSystem();
    else
       s = osimModel.updWorkingState(); 
    end
    
    %# Set the initial states of the model
    editableCoordSet = osimModel.updCoordinateSet();

    % Arrange the initial guess by nodes and states
    for ii = 1:size(InitStruct.StateVals,1) 
        VariableName = char(InitStruct.StateLabl(ii));
        SpString = split(InitStruct.StateLabl(ii),'/');
        JointName = char(SpString(1));
        CoordName = char(SpString(2));
        ValueName = char(SpString(3));
        if strcmp(ValueName,'speed')
            temp_str=char(InitStruct.StateLabl(ii));
            editableCoordSet.get(CoordName).setSpeedValue(s, InitStruct.StateVals(ii));        
        else
            editableCoordSet.get(CoordName).setValue(s, InitStruct.StateVals(ii));
        end
    end

    clear editableCoordSet temp_str str_addr;

%     for ii=1:CentStruct.Number
%     end

    joint_1 = osimModel.getCoordinateSet().get(CentStruct.Cent_cor_name(1,1));
    joint_2 = osimModel.getCoordinateSet().get(CentStruct.Cent_cor_name(1,2));
    
     q1 = joint_1.getValue(s);
    dq1 = joint_1.getSpeedValue(s);
     q2 = joint_2.getValue(s);
    dq2 = joint_2.getSpeedValue(s);

     q1_des =  CentStruct.Q_des(1,1);
    dq1_des =  CentStruct.U_des(1,1);
     q2_des =  CentStruct.Q_des(1,2);
    dq2_des =  CentStruct.U_des(1,2);
    
    disp(['joint1 vl: [' num2str(q1/pi*180.) ']/desired[' num2str(q1_des/pi*180.) '] ']);
    disp(['joint1 sp: [' num2str(dq1/pi*180.) ']/desired[' num2str(dq1_des/pi*180.) '] ']);
    disp(['joint2 vl: [' num2str(q2/pi*180.) ']/desired[' num2str(q2_des/pi*180.) '] ']);
    disp(['joint2 sp: [' num2str(dq2/pi*180.) ']/desired[' num2str(dq2_des/pi*180.) '] ']);
    
    % controlLaw = Vector( 2, 0.0 );
    q = zeros(1,2); %   q = Vector( 2, 0.0 );
    q(1) = q1; q(2) = q2; % q.set(0, q1); q.set(1, q2);
    dq = zeros(1,2); % dq = Vector( 2, 0.0 );
    dq(1) = dq1; dq(2) = dq2; % dq.set(0, dq1); dq.set(1, dq2);
    q_des = zeros(1,2); % q_des = Vector( 2, 0.0 );
    q_des(1) = q1_des; q_des(2) = q2_des; % q_des.set(0, q1_des); q_des.set(1, q2_des);
    dq_des = zeros(1,2); % dq_des = Vector( 2, 0.0 );
    dq_des(1) = dq1_des; dq_des(2) = dq2_des; % dq_des.set(0, dq1_des); dq_des.set(1, dq2_des);
    
    KP = diag(CentStruct.kp(1,1:2)); 
    KV = diag(CentStruct.kv(1,1:2)); % KP = Matrix( 2, 2, 0.0 ); KV = Matrix( 2, 2, 0.0 );
    % KP.set( 0, 0, kp ); KP.set( 1, 1, kp );
    % KV.set( 0, 0, kv ); KV.set( 1, 1, kv );
    
    controlLaw = zeros(1,CentStruct.Number);
    
    controlLaw = (-1. * KP*(q - q_des)' - KV*(dq - dq_des)')';
    
    controlLaw_Full = zeros(1,s.getNU);
    controlLaw_Vector = Vector(s.getNU(), 0.0);
    
    for ii=1:CentStruct.Number
        controlLaw_Full(1,CentStruct.ValAd(1,ii)) = controlLaw(1,ii);
        controlLaw_Vector.set(CentStruct.ValAd(1,ii)-1, controlLaw(1,ii));
    end
    
    smss = osimModel.getMatterSubsystem();

    osimModel.realizeVelocity(s);
    
    % Calculate MUDot = M * Udot
    MUDot = Vector();
    smss.multiplyByM(s, controlLaw_Vector, MUDot);
    
    M = Matrix(s.getNU(),s.getNU());
    smss.calcM(s,M);
    M_array = osimMatrixToArray(M);
    MUDot_array = (M_array * controlLaw_Full')';

    % Calculate G_vector (Gravity force vector)
    G_vector = Vector(s.getNU(),0.0);
    GrvForce = osimModel.getGravityForce();

%     % ****[ POINT 1 ]****
%     % ** This method is not wrapped for MATLAB **
%     % G_vector = GrvForce.getBodyForces(s);

    % Calculate Cq_vector (Velocity vector)
    Cq_vector = Vector();
    knownUdot = Vector(s.getNU(), 0.0);
    appliedMobilityForces = Vector();
    appliedBodyForces = VectorOfSpatialVec();
    
    smss.calcResidualForceIgnoringConstraints(s, appliedMobilityForces, appliedBodyForces, ...
        knownUdot, Cq_vector);
    
    
    % Test SimbodyMatterSubsystem.calcResidualForce().
    % ------------------------------------------------
    % For the given inputs, we will actually be computing the first column
    % of the mass matrix. We accomplish this by setting all inputs to 0
    % except for the acceleration of the first coordinate.
    %   f_residual = M udot + f_inertial + f_applied 
    %              = M ~[1, 0, ...] + 0 + 0
    
    knownLambda = Vector();
    residualMobilityForces = Vector();
    smss.calcResidualForce(s, Cq_vector, appliedBodyForces, ...
                  controlLaw_Vector, knownLambda, residualMobilityForces);
    
    % Calculate Joint torques
                  
    controlTorque = Vector();

    G_array = osimVectorToArray(G_vector);
    Cq_array = osimVectorToArray(Cq_vector);
    
    assert (size(MUDot_array,2) == size(Cq_array,2));
    
    controlTorque_array = MUDot_array + Cq_array - G_array;

    controlTorque = osimVectorFromArray(controlTorque_array);

    disp(['controlTorque: [' num2str(controlTorque_array) ']' ]);
    
    for jj=1:CentStruct.Number
        CentStruct.ContV(jj) = controlTorque.get(CentStruct.ValAd(1,jj)-1);
    end
    
    assert(controlTorque.size() == s.getNU());

    
    for ii=1:size(Control_Func.time,2)
        if Control_Func.time(ii)>time_start && Control_Func.time(ii)<=time_end
            for jj=1:CentStruct.Number
                assert(strcmp (Control_Func.name(jj), CentStruct.Cent_act_name(jj)));
                Control_Func.data(jj, ii) = CentStruct.ContV(jj);
            end
        end
    end


    % Delete old ControllerSet from the model 
    N_olderCont = osimModel.getControllerSet().getSize();
    for ii = 1: N_olderCont 
        olderController = osimModel.getControllerSet().get(ii-1);
        osimModel.removeController(olderController);
        clear olderController
    end

    clear N_olderCont 

     q1m = joint_1.getValue(s);
    dq1m = joint_1.getSpeedValue(s);
     q2m = joint_2.getValue(s);
    dq2m = joint_2.getSpeedValue(s);

    disp(['Check Point A']);
    disp(['\njoint1 vl: [' num2str(q1m/pi*180.) ']/desired[' num2str(q1_des/pi*180.) '] ']);
    disp(['joint1 sp: [' num2str(dq1m/pi*180.) ']/desired[' num2str(dq1_des/pi*180.) '] ']);
    disp(['joint2 vl: [' num2str(q2m/pi*180.) ']/desired[' num2str(q2_des/pi*180.) '] ']);
    disp(['joint2 sp: [' num2str(dq2m/pi*180.) ']/desired[' num2str(dq2_des/pi*180.) '] ']);


    % Define a controller and add it to the model 
    ActuatorController = PrescribedController();
    ActuatorController.setName('PiecewiseLinear Controller')
    ActuatorController.setActuators(osimModel.updActuators())

    % get actuator set from model, and count the number of actuators
    model_act     = osimModel.getActuators();
    Nacts         = model_act.getSize();


    for ii = 1:Nacts
       PLF = PiecewiseLinearFunction();
       % Get the coordinate set from the model
       CurrentActs = model_act.get(ii-1);
       for jj = 1:size(Control_Func.name,2)
           if strcmp(CurrentActs.getName(), Control_Func.name(jj))
               for kk=1:size(Control_Func.time,2)
                   PLF.addPoint(Control_Func.time(kk),Control_Func.data(jj,kk));
               end
               break;
           end      
       end
       ActuatorController.prescribeControlForActuator(ii-1,PLF);
    end

    clear PLF CurrentActs model_act Nacts;

%     % ****[ POINT 2 ]****
%     % Add controller to osimModel
    osimModel.addController(ActuatorController);


    clear muscleController;

    
%     %  Save the Modified Model to a file
%     fileoutpath = ['Monitor_Model.osim'];
%     osimModel.print(fileoutpath);
%     disp(['The new model has been saved at ' fileoutpath]);
%     % 

        
%     % ****[ POINT 3 ]****
%     % Call the function that runs the simulation
%     osimModel.setPropertiesFromState(s);
%     osimModel.equilibrateMuscles(s);


    
    osimModel.initSystem();
    % Create a manager to run the simulation
    simulationManager = Manager(osimModel);
    simulationManager.setWriteToStorage(true);
    simulationManager.setPerformAnalyses(true);
    simulationManager.setInitialTime(time_start);
    simulationManager.setFinalTime(time_end);
    simulationManager.setIntegratorAccuracy(1e-04);
    
    simulationManager.integrate(s);

     q1 = joint_1.getValue(s);
    dq1 = joint_1.getSpeedValue(s);
     q2 = joint_2.getValue(s);
    dq2 = joint_2.getSpeedValue(s);

     q1_des =  CentStruct.Q_des(1,1);
    dq1_des =  CentStruct.U_des(1,1);
     q2_des =  CentStruct.Q_des(1,2);
    dq2_des =  CentStruct.U_des(1,2);
    
    disp(['2\njoint1 vl: [' num2str(q1/pi*180.) ']/desired[' num2str(q1_des/pi*180.) '] ']);
    disp(['joint1 sp: [' num2str(dq1/pi*180.) ']/desired[' num2str(dq1_des/pi*180.) '] ']);
    disp(['joint2 vl: [' num2str(q2/pi*180.) ']/desired[' num2str(q2_des/pi*180.) '] ']);
    disp(['joint2 sp: [' num2str(dq2/pi*180.) ']/desired[' num2str(dq2_des/pi*180.) '] ']);
    
    
    simulationManager.delete;
    clear simulationManager;

end

[Thomas Uchida]

When I call Manager() in C++ or MATLAB with OpenSim 3.3, I have never called secondary "initSystem". Why do we need to call it with OpenSim 4.0?

You need to call initSystem() in ForwardOsimFunction_171026.m on line 247 (i.e., before constructing the Manager) because you have modified the model above (e.g., osimModel.addController(ActuatorController); on line 227). Modifying the model (by adding components, modifying properties, etc.) invalidates the underlying computational system because the model is now governed by a different system of equations. Calling initSystem() builds a fresh computational system. You should build the model, call initSystem(), and then initialize the states in the system. The same workflow applies to 3.3.

[Hideyuki Kimpara]

Dear Tom,

Thank you for your comments. But after the initSystem(), the state variables such as joint_1.getValue(s) has been changed to default as defined on Osim file.
When we wish to execute Manager with updated controller with updated state variables, what modification is necessary?

Thank you,
Hide

[Thomas Uchida]

But after the initSystem(), the state variables such as joint_1.getValue(s) has been changed to default as defined on Osim file. When we wish to execute Manager with updated controller with updated state variables, what modification is necessary?

You can either set the value of joint_1 after calling initSystem(), or you could change the default value of the coordinate.

[Hide Kimpara]

Dear Tom,

Your suggestion made getting a solution for me. I set state variables after calling initSystem, then my feedback control system is working.
In previous cases, I used (setPropertiesFromState) instead of calling initSystem(). I assume (setPropertiesFromState) made similar roll what initSystem() is doing.
Current my understanding is initSystem() is required when I add something to osimModel. But exchanging state variables does not cause any necessary.

Again, thank you so much for your suggestion!
Best regards,
Hide

[Thomas Uchida]

Great that you got it working. You may want to check out the draft of the API documentation here: https://simtk-confluence.stanford.edu/d ... 507&api=v2 (from the "Developer's Workshop 2016" page in the Confluence documentation, here: https://simtk-confluence.stanford.edu/d ... kshop+2016).