positionsensor.md

PositionSensor

Derived from Device.

PositionSensor {
  SFFloat noise       0   # [0, inf)
  SFFloat resolution -1   # {-1, [0, inf)}
}

Description

A PositionSensor node can be used in a mechanical simulation to monitor a joint position. The position sensor can be inserted in the device field of a HingeJoint, a Hinge2Joint, a SliderJoint, or a Track. Depending on the Joint type, it will measure the angular position in radian [rad] or the linear position in meter [m].

Field Summary

• noise: This field allows to define the standard deviation of the Gaussian noise added to the sensor output. The noise is expressed in meter [m] if the parent node is a SliderJoint or a Track. It is expressed in radian [rad] if the parent node is a HingeJoint or a Hinge2Joint.

• resolution: This field allows to define the resolution of the sensor, the resolution is the smallest change that it is able to measure. Setting this field to -1 (default) means that the sensor has an 'infinite' resolution (it can measure any infinitesimal change). Otherwise, this field accepts values in the interval (0.0, inf). The resolution is expressed in meter [m] if the parent node is a SliderJoint or a Track. It is expressed in radian [rad] if the parent node is a HingeJoint or a Hinge2Joint.

PositionSensor Functions

wb_position_sensor_enable

wb_position_sensor_disable

wb_position_sensor_get_sampling_period

wb_position_sensor_get_value

wb_position_sensor_get_type

%tab-component "language"

%tab "C"

#include <webots/position_sensor.h>

void wb_position_sensor_enable(WbDeviceTag tag, int sampling_period);
void wb_position_sensor_disable(WbDeviceTag tag);
int wb_position_sensor_get_sampling_period(WbDeviceTag tag);
double wb_position_sensor_get_value(WbDeviceTag tag);
int wb_position_sensor_get_type(WbDeviceTag tag);

%tab-end

%tab "C++"

#include <webots/PositionSensor.hpp>

namespace webots {
  class PositionSensor : public Device {
    enum {ROTATIONAL, LINEAR};

    virtual void enable(int samplingPeriod);
    virtual void disable();
    int getSamplingPeriod() const;
    double getValue() const;
    int getType() const;
    // ...
  }
}

%tab-end

%tab "Python"

from controller import PositionSensor

class PositionSensor (Device):
    ROTATIONAL, LINEAR

    def enable(self, samplingPeriod):
    def disable(self):
    def getSamplingPeriod(self):
    def getValue(self):
    def getType(self):
    # ...

%tab-end

%tab "Java"

import com.cyberbotics.webots.controller.PositionSensor;

public class PositionSensor extends Device {
  public final static int ROTATIONAL, LINEAR;

  public void enable(int samplingPeriod);
  public void disable();
  public int getSamplingPeriod();
  public double getValue();
  public int getType();
  // ...
}

%tab-end

%tab "MATLAB"

WB_ROTATIONAL, WB_LINEAR

wb_position_sensor_enable(tag, sampling_period)
wb_position_sensor_disable(tag)
period = wb_position_sensor_get_sampling_period(tag)
value = wb_position_sensor_get_value(tag)
type = wb_position_sensor_get_type(tag)

%tab-end

%end

Description

enable, disable and read position sensor measurement

The wb_position_sensor_enable function enables measurements of the joint position. The sampling_period argument specifies the sampling period of the sensor and is expressed in milliseconds. Note that the first measurement will be available only after the first sampling period elapsed.

The wb_position_sensor_disable function turns off the position sensor to save CPU time.

The wb_position_sensor_get_sampling_period function returns the period given into the wb_position_sensor_enable function, or 0 if the device is disabled.

The wb_position_sensor_get_value function returns the most recent value measured by the specified position sensor. Depending on the type, it will return a value in radian [rad] (angular position sensor) or in meter [m] (linear position sensor).

The wb_position_sensor_get_type function returns the type of the position sensor. It will return WB_ROTATIONAL if the sensor is associated with a HingeJoint or a Hinge2Joint node, and WB_LINEAR if it is associated with a SliderJoint or a Track node.

---

wb_position_sensor_get_brake

wb_position_sensor_get_motor

%tab-component "language"

%tab "C"

#include <webots/position_sensor.h>
#include <webots/brake.h>
#include <webots/motor.h>

WbDeviceTag wb_brake_get_brake(WbDeviceTag tag);
WbDeviceTag wb_brake_get_motor(WbDeviceTag tag);

%tab-end

%tab "C++"

#include <webots/PositionSensor.hpp>
#include <webots/Brake.hpp>
#include <webots/Motor.hpp>

namespace webots {
  class PositionSensor : public Device {
    Brake *getBrake() const;
    Motor *getMotor() const;
    // ...
  }
}

%tab-end

%tab "Python"

from controller import PositionSensor, Brake, Motor

class PositionSensor (Device):
    def getBrake(self):
    def getMotor(self):
    # ...

%tab-end

%tab "Java"

import com.cyberbotics.webots.controller.PositionSensor;
import com.cyberbotics.webots.controller.Brake;
import com.cyberbotics.webots.controller.Motor;

public class PositionSensor extends Device {
  public Brake getBrake();
  public Motor getMotor();
  // ...
}

%tab-end

%tab "MATLAB"

tag = wb_brake_get_brake(tag)
tag = wb_brake_get_motor(tag)

%tab-end

%end

Description

get associated devices

The wb_position_sensor_get_brake and wb_position_sensor_get_motor functions return the Brake and Motor instances defined in the same Joint or Track device field. If none is defined they return 0.