6.4.2. Head sensor

To enable any teleoperation, the dVRK needs to know if the operator is present and holding the MTMs. On the clinical systems, there is a sensor at the level of the stereo display to detect if the operator’s head is facing the display. On the first versions of dVRKs, we didn’t have a head sensor so we used one of the foot pedals as a deadman switch. The operator was considered present if and only if the “COAG” pedal was pressed. Having to press the pedal continuously is quite inconvenient so we came up with a few alternatives.

Note

Your systems should have only one head sensor, make sure you refer to the correct section.

See also dMIB IOs.

6.4.2.1. da Vinci head sensor

If you’ve built your custom cable to interface with the original head sensor, you can modify your console JSON configuration file.

Assuming that you’re connecting your head sensor to the MTMR controller, always on the DOF 1 connector, you just need to add the following line in your console JSON configuration file:

"operator-present": {
  "io": "io/sawRobotIO1394-MTMR-dv-head-sensor.xml"
}

Warning

The board numbering on the software side starts with index 0 (e.g. in XML IO configuration file) but the labels on the back of the controller start at index 1. Keep this in mind if you plan to connect the head sensor to another “DOF” and create your own XML configuration files.

6.4.2.2. Goovis head sensor

For the Goovis HMD, we added a lightweight HID class to the dVRK code to get access to the head sensor. The code can be found in component/code/mtsHIDHeadSensor.cpp. The component has a default configuration file under share/hid/goovis-hd.json which contains:

{
  "id_vendor": "880a",
  "id_product": "3501",
  "index_data": 17
}

Then in your console’s JSON configuration file you should add:

"operator-present":
{
  "hid": "hid/goovis-hd.json"
}

6.4.2.3. dVRK head sensor

Assuming you’ve built your custom head sensor, you can modify your console JSON configuration file.

There is no specific IO configuration to perform at that point provided that you connect the head sensor on the same controller as the foot pedals (for rev 1.5 and above, HEAD is already included in the IO foot pedal XML files)

Update your JSON config file to set the presence sensor or point to the IO foot pedal configuration file (rev 1.5+)

"console-inputs": {
  "operator-present": {
     "component": "io",  // hard coded in source code, file mtsIntuitiveResearchKitConsole.cpp
     "interface": "Head" // name of the button you want to use, defined in sawRobotIO1394 configuration file
  }
}