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.
Simulator direct drive FFB wheel is operational but currently it lacks other controls. Mechanical parts design and tooling was implemented by Aki.
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.
Load endurance test with IONI Pro and IONI Pro HC
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’ve got our hands on the pilot run high current IONIs yesterday! Everything is working as expected which makes development straightforward.
Today I spent full day adapting the drive firmware, bootloader firmware and testing application to support the new hardware. It took some time to create a system where the one and only firmware runs on both hardware models. Firmware detects the underlying hardware model and automatically adjusts it’s operation accordingly.
Thank you for all the great name proposals! We are having difficult time choosing one among so many good options. The winner will be announced soon :)
We will be soon receiving a pilot batch of the new enhanced IONI model with the best-in-class power MOSFET transistors to increase the current capacity. Other change is an increase of voltage sense range, which will allow few volts more usable voltage range.
We’re thinking the naming of it. I thinki IONI HC Pro would sound clumsy. Perhaps something like IONI XPro would suit better. What do you think? Or perhaps give an idea in comments. If your suggestion is chosen, you will win a free high current IONI with the very first serial number!
Update: we will arrange a poll within our staff to pick the winner! All entries before Monday 12 October will make it to the voting. Keep the ideas coming!
We have started tweaking the IONI drive in order to push it beyond it’s present output current limits. This includes testing of lower loss power MOSFETs and current sensing resistors to achieve reduced heat dissipation. So far we have achieved 35-40% reduction of heat dissipation at high currents.
MOSFET replacement work in progress. The new ones are already installed on right side. These particular transistors have exposed top side thermal pad for external heat sinking.
Due to popular demand, we brought BL series servo motors back in stock!
They have little bit different specifications than the earlier BL series motors. Now these motors are rated between 24 and 48 VDC which makes them ideal match with IONI drives. Also BL70 series motors have been upgraded from 4 000 CPR to 10 000 CPR encoders for smoother and stiffer operation.
The new IONI firmware version has been released! It adds long awaited SinCos encoder support to the drive.
See the video below as comparison of SinCos and incremental encoder. The main advantages of SinCos are: silent (no dither), more stiffness and more precision. The only drawbacks are the availability and price of such encoders.
The other added features include application specific functionality for torque mode. This includes rotation limit (added safety) and torque setpoint scaling by analog input. These may be useful especially for OpenSimWheel project builders.
We have been quietly experimenting on a special IONI motherboard that has discrete power stage to extend IONI power capability. We already have a proof-of-concept board that is equipped with leftover VSD-E mosfets (61A 200V rated). After couple of weeks of use, we could not tell the difference between integrated and external power stage by observing motor control performance and smoothness.
IONIZER proof-of-concept board
Bottom side showing the discrete power MOSFETs
IONIZER has been considered to be available as DIY board (bare PCB) and a reference design where users could modify it to match virtually any power need. However, it’s not ready and many changes are needed to have our approval (such as galvanic isolation of all I/O, short circuit protection and switch to PCI-E 8x socket for newer IONI). Finishing this might be a subject for another crowd funding project.
Some pros are:
Can be made to virtually any power
Not highly expensive
If built with assembly errors, can be hazardous
Some safety & protection features add complexity on circuity (STO, over temperature & short circuit protections)
Industrial manufacturing may not be cost effective (more complex solution than Argon)
Tell me in the comments how useful do you see IONIZER and which voltage & current range would be your preference :)
The prototype IONICUBE 1X has been now assembled and tested. Functionally everything is Ok, which is the most important thing, but few adjustments in layout and component selection will be made. No big deal – no delay!
IONICUBE 1X prototype (with temporary type pin header etc)
In the other news, we’re over $30k in the Indiegogo campaign! Pure awesomeness! This means that the very next IONI firmware release will buff current rating to 18 Amps on devices that are sent for the campaign contributors :)