In other words, we’re now hiring the best of the best hacker available to take a major role in servo drive firmware development. If your socks started spinning already, don’t miss this once-in-a-lifetime chance and drop Granite Devices your CV now!
Prototypes of SimuCUBE motherboards and acrylic case have just arrived! The first successful test drive has been done with a big smile :) We hope to have Indiegogo campaign launched on the next week. Get ready for early bird specials!
Ingenious SimuCUBE hardware & enclosure design and photos by Aki.
I’m happy to reveal the details of the upcoming force feedback controller – SimuCUBE! The hardware design is now complete for prototyping and we will get prototypes in the lab in the next month. SimuCUBE has a STM32F4 microcontroller that is compatible to a popular STM32F4 Discovery board. The plan is to start an open source firmware project for this board.
Brilliant hardware design & image render by Aki.
Today’s development on IONI Pro has revolved around the development of feature called Peak power limit. With that, user can set the exact amount of Watts that drive is allowed to transfer from PSU to motor.
This may be useful when using drive from a switch mode power supplies that normally shut down on overload condition. With this parameter, one can set exact amount of power that is available from PSU to prevent overloads. This also helps to save money on power supply as there is less need oversize the PSU in order to handle the highest load peaks.
Our FFB wheel build is taking big steps forward. This rig may have world’s first laser gas & brake pedals. And the biggest wheel motor too!
Thanks to Aki for design, tooling and video. Stay tuned for more progress, during this time we have have got many ideas how to improve electronics & software of FFB systems.
To celebrate the new year 2016, we have released a new IONI firmware version 1.4.0. It includes rewritten torque controller that uses 32 bit floating point precision arithmetics instead of integer arithmetics. As IONI has hardware FPU, it yielded faster code execution time as well. This makes more room for the new upcoming features.
- IONI Pro HC model maximum output current in AC/BLDC/Stepper modes increased to 25A (was 23A)
- Re-implemented torque controller using 32 bit floating point arithmetics instead of integer arithmetics (at least theoretical precision improvement)
- DC motor mode no longer requires parallel connection of drive output phases if current is at most 50% of drive’s maximum output current capability (sensitivity of overcurrent fault with Fault ID 440219 is greatly reduced).
- Changed limit switch polarity: earlier limit switches needed to be normally open (NO), while drive specifications say that they are normally closed type (NC). Now limit switchers are NC (switch conducting -> motion allowed, switch open -> motion stops).
- Fix an issue where AC/BLDC motor initialization could become incorrectly phased when Hall sensors are enabled
- Address an issue where torque was 5% lower than setpoint with TBW parameter value of 4700 Hz
Get it from here.
The decision to build a racing simulator with servo motor based force feedback has yielded first tangible results. The picture below shows the current setup of a force feedback wheel with a 36 Nm (peak) motor equipped with a sin/cos encoder. The system is being driven by IONI Pro HC and a STM32 Discovery based interface.
The first test drive on iRacing put a wide smile on our faces immediately and gave more motivation to make faster progress on it :)
The plan is to experiment with wheel effect calculations, such as friction, inertia, damping and spring, inside the drive firmware to take full advantage of high resolution feedback devices. Also it’s a good platform to test how far IONI can be pushed in output current ratings in this kind of system.
We run number of tests to each manufactured drive, one of them being a load endurance test. The test is done by driving constant 9 Amp sinusoidal current from all four power lanes and clocking the time of how long it takes drive to heat up by 25 Celsius. This test is used to verify proper characteristics of the power stage. Each tested drive must score above a certain level of endurance to be passed.
The statistics above shows endurance results from about 200 tested drives. From here we can see that Pro HC model has average endurance times of 47.7 seconds while Pro has average of 27.5 seconds. This means that on average HC model takes 1.73 times longer to get equally warm during the test. On the other hand, it could be understood that on average HC model dissipates 42% less heat.
The test also reveals that the variance is higher on HC model. There are few extraordinary good units probably due to varying characteristics of the MOSFETs even though both model MOSFETs are made by same manufacturer. Pro HC model uses the newest and lowest loss type that is available today in this size while Pro uses couple of steps lower rated devices. I hope some day the MOSFET manufacturer manages to avoid the variance and start offering transistors that perform like the best ones seen here.
Despite of the variance, the best thing is that there is clear bottom level on both types, so any unit will not have troubles meeting the specs.
We have released new firmware files for Argon and Ioni today. Also Granity has been updated.
Argon V2.0.0 beta 4
All reported bugs have been addressed. Beta 4 is a release candidate and it will become official 2.0 if no further problems are found. Once tested, please send feedback about it (email or comment here, also please tell which control mode you are using: torque, velocity or position). Or give vote on the poll on the right sidebar. Get the firmware from here.
This update includes lots of changes since the last release. For full change log and downloads, see this wiki page. Feedback is very welcome.
Development today focused on improving torque smoothness of motors. Some motors, especially cheaper ones and stepping motors, suffer from cogging torque:
“Cogging torque of electrical motors is the torque due to the interaction between the permanent magnets of the rotor and the stator slots of a Permanent Magnet (PM) machine. It is also known as detent or ‘no-current’ torque. This torque is position dependent and its periodicity per revolution depends on the number of magnetic poles and the number of teeth on the stator.”
This can be compensated by modulating motor current to counter the motor cogging. The firmware under development adds options to adjust compensation current by few new parameters.
In addition to cogging torque, the new feature allows compensating also nonuniformity of torque production. I.e. if motor torque setpoint is kept constant and motor is being turned, it may produce variable amount of torque due to same reasons than cogging. Nonuniformity compensation will modulate the torque setpoint by a selected sine or cosine function and amplitude.
The new feature beta will become available for IONI Pro in the soon upcoming FW release. We hope that this will bring cost of any motor control system down as cheaper motor could achieve nearly same smoothness as expensive ones.