vacuumgripper.md

Vacuum Gripper

Derived from Device and Solid.

VacuumGripper {
  SFBool   isOn              FALSE         # {TRUE, FALSE}
  SFFloat  tensileStrength   -1            # {-1, [0, inf)}
  SFFloat  shearStrength     -1            # {-1, [0, inf)}
  SFInt32  contactPoints     3             # [1, inf)
}

Description

The VacuumGripper node is used to simulate physical links created by vacuum suction.

The physical connection can be created and destroyed at run time by the robot's controller. The VacuumGripper node can connect to dynamic Solid nodes, e.g., for pick and place operations, as well as to the static environment, e.g., for locomotion. Then, the detection of the presence of an object to connect to is based on collision detection.

Field Summary

• isOn: represents the state of the VacuumGripper. The state can be changed through the wb_vacuum_gripper_turn_on and wb_vacuum_gripper_turn_off API functions. The on state just means that the suction pump is active, but it does not indicates whether or not an actual physical link exists with an object. The actual physical link exists only if a valid Solid object collided with the VacuumGripper after the wb_vacuum_gripper_turn_on function was called.

  Note: If the VacuumGripper node is on in the .wbt file and a valid Solid node is available, then the simulation will automatically connect to the Solid object. You can take advantage of this feature to start your simulation with the desired mechanical configuration.

• tensileStrength: maximum tensile force in newton [N] that the suction mechanism can withstand before it breaks. This can be used to simulate the rupture of the suction mechanism. The tensile force corresponds to a force that pulls the two objects apart (in the negative x-axes direction). When the tensile force exceeds the tensile strength, the link breaks. The default value -1 indicates an infinitely strong suction mechanism that does not break no matter how much force is applied.

• shearStrength: indicates the maximum shear force in newtons [N] that the suction mechanism can withstand before it breaks. This can be used to simulate the rupture of the suction mechanism. The shearStrength field specifies the ability of the suction mechanism to withstand a force that would makes them slide against each other in opposite directions (in the yz-plane). The default value -1 indicates an infinitely strong suction mechanism that does not break no matter how much force is applied.

• contactPoints: indicates the minimum number of contact points with the Solid object required to connect.

VacuumGripper Functions

wb_vacuum_gripper_enable_presence

wb_vacuum_gripper_disable_presence

wb_vacuum_gripper_get_presence_sampling_period

wb_vacuum_gripper_get_presence

%tab-component "language"

%tab "C"

#include <webots/vacuum_gripper.h>

void wb_vacuum_gripper_enable_presence(WbDeviceTag tag, int sampling_period);
void wb_vacuum_gripper_disable_presence(WbDeviceTag tag);
int wb_vacuum_gripper_get_presence_sampling_period(WbDeviceTag tag);
bool wb_vacuum_gripper_get_presence(WbDeviceTag tag);

%tab-end

%tab "C++"

#include <webots/VacuumGripper.hpp>

namespace webots {
  class VacuumGripper : public Device {
    virtual void enablePresence(int samplingPeriod);
    virtual void disablePresence();
    int getPresenceSamplingPeriod() const;
    bool getPresence() const;
    // ...
  }
}

%tab-end

%tab "Python"

from controller import VacuumGripper

class VacuumGripper (Device):
    def enablePresence(self, samplingPeriod):
    def disablePresence(self):
    def getPresenceSamplingPeriod(self):
    def getPresence(self):
    # ...

%tab-end

%tab "Java"

import com.cyberbotics.webots.controller.VacuumGripper;

public class VacuumGripper extends Device {
  public void enablePresence(int samplingPeriod);
  public void disablePresence();
  public int getPresenceSamplingPeriod();
  public boolean getPresence();
  // ...
}

%tab-end

%tab "MATLAB"

wb_vacuum_gripper_enable_presence(tag, sampling_period)
wb_vacuum_gripper_disable_presence(tag)
period = wb_vacuum_gripper_get_presence_sampling_period(tag)
presence = wb_vacuum_gripper_get_presence(tag)

%tab-end

%end

Description

detect the presence of a connected object

The wb_vacuum_gripper_enable_presence function starts querying the presence of a linked Solid object. The sampling_period argument specifies the sampling period of the presence sensor. It is expressed in milliseconds. Note that it will be active only after the first sampling period elapsed.

The wb_vacuum_gripper_disable_presence function stops querying the presence sensor of a linked Solid object.

The wb_vacuum_gripper_get_presence_sampling_period function returns the period at which the presence sensor of the linked Solid object is queried. The wb_vacuum_gripper_get_presence function returns the current presence state, it returns TRUE if a Solid object is connected and FALSE otherwise.

---

wb_vacuum_gripper_turn_on

wb_vacuum_gripper_turn_off

wb_vacuum_gripper_is_on

%tab-component "language"

%tab "C"

#include <webots/vacuum_gripper.h>

void wb_vacuum_gripper_turn_on(WbDeviceTag tag);
void wb_vacuum_gripper_turn_off(WbDeviceTag tag);
bool wb_vacuum_gripper_is_on(WbDeviceTag tag);

%tab-end

%tab "C++"

#include <webots/VacuumGripper.hpp>

namespace webots {
  class VacuumGripper : public Device {
    virtual void turnOn();
    virtual void turnOff();
    virtual bool isOn()
    // ...
  }
}

%tab-end

%tab "Python"

from controller import VacuumGripper

class VacuumGripper (Device):
    def turnOn(self):
    def turnOff(self):
    def isOn(self):
    # ...

%tab-end

%tab "Java"

import com.cyberbotics.webots.controller.VacuumGripper;

public class VacuumGripper extends Device {
  public void turnOn();
  public void turnOff();
  public boolean isOn();
  // ...
}

%tab-end

%tab "MATLAB"

wb_vacuum_gripper_turn_on(tag)
wb_vacuum_gripper_turn_off(tag)
on = wb_vacuum_gripper_is_on(tag)

%tab-end

%end

Description

create / destroy the physical connection wit a solid object

The wb_vacuum_gripper_turn_on and wb_vacuum_gripper_turn_off functions can be used to activate or deactivate the VacuumGripper suction pump and changing the status of the isOn field. This will eventually create or destroy the physical connection with a Solid object.

If dynamic Solid object collides with the VacuumGripper while the device is on, a physical link will be created between the VacuumGripper and the Solid object. The two connected bodies will then keep a constant distance and orientation with respect to each other from this moment on.

If the wb_vacuum_gripper_turn_off function is invoked while there is a physical link between the VacuumGripper and a Solid object, the link will be destroyed.