General info for all sensors

What a sensor is

A sensor reads a value of the model - an output variable of a node, an object, a body at a point, a marker, or the value of a load - and does not act on the system. Every sensor page says only what it is attached to and what it measures; what follows is the same for all of them.

What a sensor measures

outputVariableType selects the quantity, an exu.OutputVariableType, and the item the sensor is attached to must provide it: the page of the item lists its output variables with their symbols and frames. Asking for one the item does not provide is an error of mbs.Assemble().

When and where the values go

During a simulation, the solver evaluates every sensor at the times given by simulationSettings.solution.sensors.writePeriod, and

• writes a line time, value[0], value[1], ... to the file fileName, if writeToFile = True and a file name is given; the directory is created if it does not exist, and a header and a footer describe the sensor (sensorsWriteFileHeader, sensorsWriteFileFooter);

• stores the same rows in memory if storeInternal = True, which mbs.GetSensorStoredData(sensor) returns as an array, one row per time;

• does neither if solution.sensors.active = False.

solution.sensors.append appends to an existing file, or to the stored data, so that several simulations continue one record.

Reading a value at any time

mbs.GetSensorValues(sensor, configuration) returns the value now, in the current configuration by default, without storing it.

Plotting

mbs.PlotSensor(sensor, ...) plots the stored or written values over time, several sensors and components at once; the results monitor shows sensor files while a simulation runs.

Values computed from other sensors

SensorUserFunction computes its value with a Python function from the values of other sensors, e.g. to transform them into another frame or to combine them; it is stored and written like any other sensor.

Drawing

Sensors are drawn as small symbols; with visualizationSettings.sensors.traces the positions, and vectors or frames, of position sensors are drawn along their history.

Drawing

A sensor is drawn if sensors.show and its own show are True, at the position it measures: a symbol of size sensors.defaultSize - a fraction of openGL.advanced.initialMaxSceneSize if -1 -, simple with sensors.drawSimplified, in sensors.defaultColor. sensors.showNumbers writes its number. A sensor without a position draws nothing; traces of sensors are drawn with sensors.traces.

The settings: sensors.show, sensors.defaultSize, sensors.defaultColor, sensors.drawSimplified, sensors.showNumbers, openGL.advanced.initialMaxSceneSize.