(2025-06-09, 12:37 PM)Embla Wrote: Hi,
I'm looking for guidance on selecting the most suitable PyPilot motor controller for my setup. My goal is to re-use the Raymarine T2 linear drive currently installed on my yacht, while replacing the legacy Raymarine control system.
Current Setup (to be replaced):- Drive: Raymarine Type 2 Linear Drive
- Controller: Raymarine ST6001 with Course Computer SmartPilot S3 (E12055, v3.02)
- Fluxgate Compass: E12102 (seems faulty)
- Wireless Remote: Raymarine Smart Controller
Most of this system is destined for the bin, aside from the T2 drive, which I hope to reuse.
New Setup (in progress):- RPi 5 with OpenPlotter
- MacArthur HAT + IMU
- Pololu voltage regulator
- PyPilot already running well on the Pi
When I began this project, the official PyPilot motor controllers were out of stock, so I experimented with a revised version of the motor control code on an ESP32 and H-bridge on the bench. That was a great learning experience, but now that the controllers are back in stock, I’m considering buying one to simplify the installation.
I see there are now 2 controller options available in the OpenMarine shop:
- PyPilot Motor Controller (by PyPilot)
- PyPilot Motor Controller (by Navitop)
I have a few questions before proceeding:
- Compatibility & Build: Are both units equally suitable for a Raymarine T2 drive? (12V, high-torque, intermittent duty cycle.) The Navitop version appears to have lighter-duty connectors—do you recommend one over the other in terms of robustness and marine suitability?
- Microcontroller Presence: Do these boards include an onboard microcontroller (e.g., Arduino or STM32), or do they require an external MCU to interface with PyPilot?
- Firmware Updates: I couldn’t see a USB port on the shop photos—how is firmware updated? Is OTA supported, or is serial flashing required through pin headers?
- Reliability Considerations: Are there particular recommendations for ensuring robust performance in a marine environment? (E.g., external fusing, motor protection, waterproofing, RF filtering, etc.)
- PyPilot Codebase: Lastly, could you clarify the current status of the PyPilot code on the RPi? I saw forum references suggesting that the Raspberry Pi PyPilot packages might lag behind the GitHub master. Is that still the case, or is the latest code now integrated in OpenPlotter packages?
Many thanks for any advice or recommendations you can offer. I’d rather invest in the right hardware now than struggle later with reliability issues offshore.
Best regards,
Paul
0 - Answer to question "compatibility wit T2 Raymarine"
Hydraulic pumps consume maximum power when applying force, particularly at the limit stop. The force is then proportional to the pressure (kg of force = pressure in bar x cm² of cylinder section).
Some hydraulic pumps, such as the Raymarine Type 2, can reach 100 bar of pressure, consuming 24A. In the absence of stroke and/or current limitations, this equates to applying a force of 585 kg, according to the Raymarine documentation.
On our sailboats, few steering systems can withstand such force without damage. It is therefore important to install limit switches and/or a rudder angle sensor, limiting the cylinder's stroke so as not to reach the mechanical limit stop of the rudder. However, precisely limiting the current drawn, as with Pypilot motor controllers, is another effective way to limit the cylinder's maximum force.
Using a 15A controller will not limit the speed in any way, but it will limit the maximum force in the event that the rudder angle sensor fails (a bent or disengaged connecting rod).
With a T2 hydraulic pump, it is rather judicious to limit the maximum current to 15 or 17A if you do not need a force greater than 200kg and the maximum pressure of 100 bar to operate the rudder. This can even prevent damage.
All pypilot motor controllers are generously sized and can supply much more than the nominal current. This is not a problem for them, whose transistors are very largely oversized compared to what you will find on the market. But all pypilot motor controlers are equipped with a precise current limiter that is easy to set in the pypilot settings. But whatever the actuator, there is no point, whatever the actuator, in forcing more than necessary and it is better to set the current limiter correctly to stop the actuator when it forces abnormally at the stop to first avoid unnecessary heating of the motor and especially to avoid unnecessary current consumption.
Choosing a 30A Pypilot controller primarily limits electrical losses due to internal resistance in the controller, but it's still prudent to limit the maximum current to prevent the actuator from damaging the rudder system by applying too much force.
But a 15A pypilot motor controller will be more than sized to supply the current normally drawn by a T2 hydraulic pump on most boats, i.e. a few amps to exert 50-80 kg of force.
1 - Conception
All the datasheets for the pypilot motor controllers are clear and precise. You'll see that the connectors you're worried about are WAGO 32-amp connectors. These are certified by WAGO for very harsh applications and are unlikely to loosen even under the worst vibrations.
2&3 -
Microcontroller Presence & Firmware Updates
All pypilot motor controlers have an ATmega328P microcontroller already programmed. The code is never modified but could be with an ISP connector identical to the one found on most Arduino.
4 - Reliability Considerations
All the datasheets and manuals are clear and precise. All pypilot motor controllers are protected against virtually all possible errors and include a main fuse as well as one or more automatic fuses (clutch, rudder feedback, etc.). The motor's current limitation also provides protection for a long service life. The UART connection to the pypilot computer is galvanically isolated.
Pypilot motor controllers continue to evolve as Sean has always done. The newer 15A from Navitop has the addition of: robust and practical Wago 32A connectors, redesigned power supplies, replacement of obsolete components, addition of a common mode RF filter for better EMC protection and tropicalization of the PCB.
5 -
PyPilot Codebase
Many of us have chosen to use what Sean offers in his shop: a Pi Zero with a tinypilot image (pypilot with a lightweight tinycore Linux system). This allows for a Pi Zero dedicated solely to the autopilot.
This results in a simple, energy-efficient autopilot that can be easily started and stopped with a simple switch on the electrical panel.
The latest version of pypilot is perfectly stable and has the advantage of working independently of the configuration of other applications in the various application suites that can run on a Raspberry Pi 4 or 5. Sean, who is still very active on the forum, has already stated that pypilot updates in the various application suites are independent of him, especially since they involve interactions between pypilot and other applications that can sometimes disrupt pypilot's operation.
With tinypilot, pypilot cannot be launched in duplicate on another machine or with an application suite such as Openplotter or BBN. But it is very easy to launch the pypilot_control, pypilot_calibration and pypilot_scope scripts from the Linux command line on one or more other machines. If these machines are connected to the tinypilot's Wi-Fi network, these scripts will then automatically use the tinypilot's data.
