Access violation adding Controller

[Mary K]

Hello,
I am creating my first Controller to my model before doing a Forward Simulation like this:

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	OpenSim::Model model("../mymodel.osim");

	PrescribedController* controller = new PrescribedController();
	controller->setName( "my_controller");
	controller->setActuators( model.getActuators());
	
	double control_time[2] = {0, 0.5}; // time nodes for linear function
	double control_acts[2] = {0.1, 1.0}; // force values at t1 and t2
	PiecewiseLinearFunction *control_func = new PiecewiseLinearFunction( 2, control_time, control_acts);
	control_func->setName( "lin_control_func");
		
	controller->prescribeControlForActuator(  "bifemlh_r", control_func);

	model.addController( controller);

	SimTK::State& si = model.initSystem();
	
	// Add reporters
    ForceReporter* forceReporter = new ForceReporter(&model);
    model.addAnalysis(forceReporter);

	// Create the integrator and manager for the simulation.
	SimTK::RungeKuttaMersonIntegrator integrator(model.getMultibodySystem());
	Manager manager(model, integrator);

	// Define the initial and final simulation times
	double initialTime = 0;
	double finalTime = 0.5;

	// Integrate from initial time to final time
	manager.setInitialTime(initialTime);
	manager.setFinalTime(finalTime);
	manager.integrate(si);

and I am getting this Unhandled Exception:

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Unhandled exception at 0x598bb3e3 in Mysim.exe: 0xC0000005: Access violation reading location 0xbaadf00d.

Has anyone any ideas on what is wrong?

The exception triggers when I am adding the controller (when line "model.addController( controller);" is added).

[Thomas Uchida]

There is a test case that demonstrates adding a PrescribedController to a Model in testControllers.cpp (see testPrescribedControllerOnBlock()): https://github.com/opensim-org/opensim- ... s.cpp#L212

[Mary K]

I did it like the example and still the same exception

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	// set controller
	PrescribedController controller;
	controller.setName( "my_controller");
	controller.setActuators( model.updActuators());
	controller.prescribeControlForActuator( 0, new Constant( 100));
	controller.setDisabled(false);
	model.addController( &controller);

	model.print("myModelWithController.osim");
    Model modelfileFromFile("myModelWithController.osim");

    // Verify that serialization and then deserialization is correct
	ASSERT(model == modelfileFromFile);

	SimTK::State& si = model.initSystem();
	
	// Create the integrator and manager for the simulation.
	SimTK::RungeKuttaMersonIntegrator integrator(model.getMultibodySystem());
	integrator.setAccuracy(1.0e-3);
	Manager manager(model, integrator);

	// Define the initial and final simulation times
	double initialTime = 0;
	double finalTime = 0.5;

	// Integrate from initial time to final time
	manager.setInitialTime(initialTime);
	manager.setFinalTime(finalTime);
	manager.integrate(si);

[Thomas Uchida]

Which version of OpenSim are you using? You might try adding model.buildSystem() (or model.initSystem()) immediately after loading the model. Model::addController() may be expecting to find internal data structures that haven't been built.

[Mary K]

I seem to solve this issue by adding a control function (even a zero-function) to the whole actuator set that was given to controller. Like this:

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	Constant* ccf = new Constant(1);

	string muscle_name;
	for (int i=0; i<model.getActuators().getSize(); i++)
	{
		muscle_name = model.getActuators().get(i).getName();
		if ( muscle_name == "bifemlh_r" || muscle_name == "bifemsh_r" || muscle_name == "grac_r" \
			|| muscle_name == "lat_gas_r" || muscle_name == "med_gas_r" || muscle_name == "sar_r" \
			|| muscle_name == "semimem_r" || muscle_name == "semiten_r")
			controller.prescribeControlForActuator( i, ccf);
		else 
			controller.prescribeControlForActuator( i, new Constant(0));
	}

And now I have a similar exception, but this time after the integration is completed:

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Unhandled exception at 0x06686468 in ACLsim.exe: 0xC0000005: Access violation.

Which version of OpenSim are you using? You might try adding model.buildSystem() (or model.initSystem()) immediately after loading the model. Model::addController() may be expecting to find internal data structures that haven't been built.

I use OpenSim 3.2 and tried your advice but nothing changed :/

[Mary K]

I finally solved this by creating the Controller with a pointer to the object and also creating different instances of Control Functions before assing them to the controller.
Like this:

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        // set controller
	PrescribedController* controller = new PrescribedController();
	controller->setName( "flexion_controller");
	controller->setActuators( model.updActuators());
	string muscle_name;
	for (int i=0; i<model.getActuators().getSize(); i++)
	{
		muscle_name = model.getActuators().get(i).getName();
		if ( muscle_name == "bifemlh_r" || muscle_name == "bifemsh_r" || muscle_name == "grac_r" \
			|| muscle_name == "lat_gas_r" || muscle_name == "med_gas_r" || muscle_name == "sar_r" \
			|| muscle_name == "semimem_r" || muscle_name == "semiten_r")
		{
			Constant* ccf = new Constant(1);
			controller->prescribeControlForActuator( i, ccf);
		}
		else 
		{
			Constant* zccf = new Constant(0);
			controller->prescribeControlForActuator( i, zccf);
		}
	}
	controller->setDisabled(false);
	model.addController( controller);

[Thomas Uchida]

Thanks for the update. Great that you got it working. I now see that your model has multiple muscles. If you wish to control only a few muscles in the model, you probably want to configure the controller so that it provides controls for only those muscles (using addActuator() rather than setActuators()). You could then use different controllers for different subsets of muscles, for example. Please see the example here: https://github.com/opensim-org/opensim- ... e.cpp#L775.