this is the code for an example of an arm model that produces an animation:
Code: Select all
%% Import Java libraries
import org.opensim.modeling.*
arm = Model();
arm.setName('bicep_curl');
arm.setUseVisualizer(true);
% ---------------------------------------------------------------------------
% Create two links, each with a mass of 1 kg, centre of mass at the body's
% origin, and moments and products of inertia of zero.
% ---------------------------------------------------------------------------
humerus = Body('humerus',...
1.0,...
Vec3(0),...
Inertia(0, 0, 0));
radius = Body('radius',...
1.0,...
Vec3(0),...
Inertia(0, 0, 0));
% ---------------------------------------------------------------------------
% Connect the bodies with pin joints. Assume each body is 1m long.
% ---------------------------------------------------------------------------
shoulder = PinJoint('shoulder',...
arm.getGround(),... % PhysicalFrame
Vec3(0),...
Vec3(0),...
humerus,... % PhysicalFrame
Vec3(0, 1, 0),...
Vec3(0));
elbow = PinJoint('elbow',...
humerus,... % PhysicalFrame
Vec3(0),...
Vec3(0),...
radius,... % PhysicalFrame
Vec3(0, 1, 0),...
Vec3(0));
% ---------------------------------------------------------------------------
% Add a muscle that flexes the elbow (actuator for robotics people).
% ---------------------------------------------------------------------------
biceps = Millard2012EquilibriumMuscle('biceps',... % Muscle name
200.0,... % Max isometric force
0.6,... % Optimal fibre length
0.55,... % Tendon slack length
0.0); % Pennation angle
biceps.addNewPathPoint('origin',...
humerus,...
Vec3(0, 0.8, 0));
biceps.addNewPathPoint('insertion',...
radius,...
Vec3(0, 0.7, 0));
% ---------------------------------------------------------------------------
% Add a controller that specifies the excitation of the muscle.
% ---------------------------------------------------------------------------
brain = PrescribedController();
brain.addActuator(biceps);
brain.prescribeControlForActuator('biceps',...
StepFunction(0.5, 3.0, 0.3, 1.0));
% ---------------------------------------------------------------------------
% Build model with components created above.
% ---------------------------------------------------------------------------
arm.addBody(humerus);
arm.addBody(radius);
arm.addJoint(shoulder); % Now required in OpenSim4.0
arm.addJoint(elbow);
arm.addForce(biceps);
arm.addController(brain);
% ---------------------------------------------------------------------------
% Add a console reporter to print the muscle fibre force and elbow angle.
% ---------------------------------------------------------------------------
% We want to write our simulation results to the console.
reporter = ConsoleReporter();
reporter.set_report_time_interval(1.0);
reporter.addToReport(biceps.getOutput('fiber_force'));
elbow_coord = elbow.getCoordinate().getOutput('value');
reporter.addToReport(elbow_coord, 'elbow_angle');
arm.addComponent(reporter);
% ---------------------------------------------------------------------------
% Add display geometry.
% ---------------------------------------------------------------------------
bodyGeometry = Ellipsoid(0.1, 0.5, 0.1);
bodyGeometry.setColor(Vec3(0.5)); % Gray
humerusCenter = PhysicalOffsetFrame();
humerusCenter.setName('humerusCenter');
humerusCenter.setParentFrame(humerus);
humerusCenter.setOffsetTransform(Transform(Vec3(0, 0.5, 0)));
humerus.addComponent(humerusCenter);
humerusCenter.attachGeometry(bodyGeometry.clone());
radiusCenter = PhysicalOffsetFrame();
radiusCenter.setName('radiusCenter');
radiusCenter.setParentFrame(radius);
radiusCenter.setOffsetTransform(Transform(Vec3(0, 0.5, 0)));
radius.addComponent(radiusCenter);
radiusCenter.attachGeometry(bodyGeometry.clone());
% ---------------------------------------------------------------------------
% Configure the model.
% ---------------------------------------------------------------------------
state = arm.initSystem();
% Fix the shoulder at its default angle and begin with the elbow flexed.
shoulder.getCoordinate().setLocked(state, true);
elbow.getCoordinate().setValue(state, 0.5 * pi);
arm.equilibrateMuscles(state);
% ---------------------------------------------------------------------------
% Configure the visualizer
% ---------------------------------------------------------------------------
viz = arm.updVisualizer().updSimbodyVisualizer();
viz.setBackgroundColor(Vec3(0)); % white
viz.setGroundHeight(-2)
% ---------------------------------------------------------------------------
% Simulate.
% ---------------------------------------------------------------------------
manager = Manager(arm);
state.setTime(0);
manager.initialize(state);
state = manager.integrate(10.0);it is mentioned in the example that "fiber_force" and "elbow_angle" must be printed to the console, but when I run it in MATLAB the animation runs but no information about the force nor the angle shows on the Command Window.
Should I change or add something in the code ?
thanks,
Hamed