QLA Heat Sink
The dVRK controllers use a JHU designed Quad Linear Amps board (acronyms defined in FAQ). The linear amplifiers are all mounted against a large passive heat sink (square aluminum bar). This solution provides some heat dissipation but this is not enough for the dVRK arms.
For the ECM and the SUJs, passive cooling is definitely not enough. Make sure you have upgrade your controllers with an extra heat sink and fan. The ECM arm is not as light as the PSMs and requires a fair bit more power. The second joint itself can draw close to 0.5 A continuously.
The MTMs and PSMs can run for a little while (half hour or so) without any issues but for prolonged usage, we strongly recommend to upgrade your controllers with a an extra heat sink and fan.
The QLA boards have multiple 2 pins 12 V connectors that are powered when the motor power is turned on. We can use these to power a fan for active cooling.
The screws used to mount the heat sink depend on the QLA serial number. To the best of our knowledge, although the older heat sink drawing indicates metric (M3) threads, we believe most were tapped for Imperial 4-40. The exception is build #3, with QLA S/N 4265-xx.
- QLA S/N 4265-xx: Metric M3, 8 mm long
- All other QLA: Imperial 4-40, 3/8" long
We found that a single Pentium Socket 370 heat sink and fan performs very well. There is very little manufacturing required so users can likely upgrade their controllers by themselves. We use the StarTech FANP1003LD: https://smile.amazon.com/dp/B000IXS6DW with success but other heatsinks for Socket 370 might work as well. Make sure there's a "valley" wide enough in the middle to drill a hole and accommodate a screw head (see size below). The StarTech fan also come with a plug that can be "reconfigured", i.e. using a sharp tool you can dislodge the connectors from the plug and reconfigure the plug to match the ground and +12V on the dVRK QLAs.
Parts to build 4 heat sinks with fans,
- Heat Sink: Digikey P/N ATS2192-ND http://www.digikey.com/short/3p1qw4, $19.20 (need 2, each is cut in half)
- Fan: Digikey P/N 259-1578-ND http://www.digikey.com/short/3p183v, $6.04 each (need 4)
- Connector: Digikey P/N A31017-ND Qty 10, $0.168 each
Each heat sink was first cut in half to match the length of the existing heat sink. We then drilled 3 holes, matching the spacing on the existing heat sink. We also drilled 4 holes, diameter 2.5 mm to mount the 40 mm fan. To mount the fan, we used 3 mm screws, 20 mm long. The length matches the cumulative thickness of the fan and heatsink:
To provide enough clearance for all the screws, we had to mill the heat sink fins:
With the fan:
This was tested on the SUJ controller, dSIB rev 2.0.
| Fan | Time | Temperature |
|---|---|---|
| off | 0:00 | 29 C (room) |
| off | 0:15 | 44 C |
| off | 0:30 | 50 C |
| on | 0:40 | 46 C |
| on | 0:45 | 37 C |
| on | 0:50 | 34 C |
Without the fan the temperature seems stable around 50 C. With the fan, the temperature goes down to 34 C.
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