3.4.4. SUJ
The goal is to re-use the internal cables and sensors in the SUJ passive arms for the dVRK controllers. This way all the signals from the active arms (2 D-sub connectors) can be carried all the way to the dSIB and dESSJ at the base of the patient’s cart.
3.4.4.1. Preparation
We first need to remove most of the electronics from the back of the patient cart. This is required since the cables coming from the base of the column of the cart are fairly short and need to reach the back of the dVRK controllers.
Warning
Most of the cables we need to reconnect to the dVRK controllers are plugged on the 4 RACs, on the front of the patient cart. There is one lone exception, a Z-axis cable. Make sure you keep track of this cable. All needed cables come out from a cutout in the vertical column.
Warning
Once you’ve set up the Si cart for the dVRK controllers, it’s possible but really difficult to go back to the original controllers.
The first step is to remove the cover (2 parts) on the back of the cart. The cover hold with 2 screws (use 3/16 hex wrench) and some pressure clips.
SUJ Si top cover screws
Once the screws are removed, you will need to pry out the covers. The pressure clips are fairly strong so don’t be afraid to apply some force on the cover.
SUJ Si top cover
Once the covers are removed, you should familiarize yourself with the different cables you will need to unplug from the original electronics and re-plug to the dVRK controllers. Ultimately, the RACs, back panels, bracket, cover, battery, electronics… will be removed.
SUJ Si open, top view
SUJ Si open, front view
On the top view, you can find the “Z-AXIS” connector. Make sure you squeeze the tab to unplug it. Keep that cable aside. it will be connected to the 5th dESSJ.
On the front view, you can see 4 RACs, i.e. one per active arm. Their cables are labeled SJA2, SJX, SJC and SJA1. They will need to be plugged in the dSIB for the PSM2, PSM3, ECM and PSM1 respectively.
See next section for the dESSJ and dSIB descriptions.
SUJ Si Z-Axis and mapping to dESSJ
On the front view, you can locate the 4 original RACs as well as all the connectors that will be connected to the dSIB on the dVRK controllers. There are 2 connectors from a bundle (white), a 2-wires black cable, a “FireWire B” cable (used for LVDS) and a grounding cable with a ring terminal. Bundle all these cables together and label with the name of the arm.
The upper “FireWire” cable (J10) and the bottom cable (J13) plugged into each RAC are not needed for dVRK.
SUJ Si active arm bundle
Caution
The FireWire cable is mounted on the back of the dRAC PCB, label J11. There is not much space to unplug it. We strongly recommend you detach the RAC (the whole bloc) from the large steel plate holding all 4 RACs, so you can unplug the cable without damaging the connector.
SUJ Si RAC connections
Once you’ve disconnected of the cables we need to preserve for the dVRK, you can remove all the electronic, bracket, battery… from the patient cart. Ideally there should be noting above the “shoulders” so you have a somewhat flat surface to stack the 4 dVRK Si controllers.
SUJ Si mapping from RAC to dSIB
3.4.4.2. dESSJ
The dESSJ boards are custom boards designed to replace the ESSJ in the SUJ itself.
Note
Do not trash the existing ESSJ boards, we might be able to provide support for these later on. They have better analog to digital converters than the Arduino based dESSJ.
Four ESSJ are located on the SUJ arm, under a small metal cover. For the dVRK, we use a fifth board at the base of the SUJ for the linear potentiometers located in the patient cart’s column. The 4 replacement boards in the SUJ arms are pass-through for the LVDS communication between the arm and the controller (FireWire B physical connector, not a real FireWire port). For the SUJ’s analog potentiometers, we use an Arduino with Bluetooth Low Energy (BLE) to communicate with the PC.
Warning
For the Bluetooth connection to work, do not put the metal covers back. You will also need to run a long USB3 cable close to the SUJ and plug a Bluetooth adapter since the BLE signal is pretty weak.
There are 3 different uses for the dESSJ:
For the ECM, PSM1 and PSM2: use both LVDS connectors and 3 potentiometer connectors (J4, J5 and J6) as well as power
For the PSM3: use both LVDS connectors and 4 potentiometer connectors (J4, J5, J6 and J7) as well as power
For the 5th dESSJ: there is no LVDS, but you need to connect the “z axis only” to the potentiometer cable from the SUJ column. The board must be powered using a micro USB connected to the Arduino board on the dESSJ. We don’t manufacture an enclosure for the 5th dESSJ so make sure you wrap it in a plastic bag to avoid short circuits.
SUJ Si mapping from ESSJ to dESSJ
Note
Since the 5th dESSJ doesn’t need FireWire connectors, it is usually shipped without them.
The dESSJ boards should come pre-programmed. If they’re not programmed you need to upgrade the firmware, please see https://github.com/jhu-dvrk/dESSJ-firmware
3.4.4.3. dSIB-Si
For a full system, you will need 4 dSIB adapter boards, one for each dVRK-Si controller (da Vinci Setup Interface Board). These boards are plugged between the dVRK Si controllers and the original cables coming at the base of the SUJ column. These boards allow us to re-use the internal cables in the SUJ arms. The cables coming from the column are unfortunately very short, so you will have to remove the cover on the back of the SUJ as well as most of the existing electronics at the base of the patient cart. The dSIB boards are also used to power the SUJ brakes.
3.4.4.4. JHU setup
The following images show the dVRK Si at Johns Hopkins. We strongly recommend putting labels everywhere to avoid confusing cables, controllers and boards. The labels should have the arm name and, when needed, the arm serial number as well as the MAC address of the dESSJ board.
dESSJ on SUJ PSM3 (bottom) and ECM (top)
Stack of dVRK-Si controllers with data cables (front)
Stack of dVRK-Si controllers with dSIB-Si (back)
Label on each active Si arm