chibi-XSIM is an STM32F4 Discovery based motor controller for the X-Sim motion simulator software.

X-Sim is a Windows application designed to power motion simulator hardware for racing and flightsim games. The chibi-XSIM project demonstrates the feasibility of STM32F4 Discovery powered motion simulators and offers an exciting level of performance through its unique choice to ride upon a real time operating system core–as found in ChibiOS/RT. It's offered here as a demonstration project and possible launch pad for others.

I would be excited to see what anyone develops from this!

Spring 2013 saw the announcment of a project called Open6DOF High Speed to spotlight the potential of Discovery-based motion simulators. The firmware for that project, though never released, is what is being offered here in its embryonic form as chibi-XSIM.

chibi-XSIM represents how far Open6DOF High Speed got before its plug was pulled; a snapshot of its state of development as of June 2013.

Let's see...

• X-Sim interface: CHECK
• User Interface: CHECK
• Advanced PID Implementation: CHECK
• Valet mode, Agression Presets, Data Logging, RTOS-based, 100 kHz Precision: CHECK
• Game Tested: CHECK
• Practical...? BIG QUESTION MARK

While standing back to reflect upon his mad creation, the author asked himself how accessible Open6DOF High Speed would be for others. The problem: an unfriendly and horribly complicated development tool chain was at its core. Think: Arduino's Opposite.

It worked wonderfully, though, humming along in all its ChibiOS/RT-powered glory with 0.01 millisecond Dependant Ideal PID implemented precision. It even had a nifty user interface menu system where a guy could plug it into his computer while it was running to tweak settings.

My vision, however, was a project people across the world could plug into easily, add their shared contribution, and elevate it to something amazing....and this just didn't feel like it; appealing only to the select few, perhaps.

Just to put it out there anyway, man!

Open6DOF's been taken out of storage, dusted off, rebranded, and GitHubbed for all to see. While it's only a subset of the Open6DOF project, it does still offer that useful bridge between the X-Sim middleware and any imaginable motor actuator out there.

Currently written for only two motors and the Pololu brushed DC motor controller, chibi-XSIM can easily be expanded to support any kind of motor, hydraulic or pneumatic system and as many working axes as desired.

EX: Racing Game ↔ X-Sim ↔ Discovery Board ↔ H-bridges ↔ DC Motors ↔ Roll/Pitch

The board connects to the PC via a USB-hosted serial cable to receive streamed position commands from X-Sim, and to H-bridge motor controllers to provide the required PWM motion and direction signals. A second cable connects to your PC for the chibi-XSIM on-screen control user interface. There you navigate various menus to make on-the-fly PID changes and to follow a calibration "wizard" for initial end points setup.

The current firmware offers:

• X-Sim and xSimCTRL software protocol compatibility.
• Support for 3 DOF (Stewart transforms for 6 DOF not implemented)
• On screen Setup menu (through your terminal emulator)
• Emergency Stop, Return-to-Center, Machine Calibration Wizard, and adjustable Deadzones
• Five agression level presets
• Data Logging
• PID tuning by real time performance graphs (see below)
• P-only, PI-only, and both PID mode variants (Independent and Dependent)
• An attempt to offer IMC ("Internal Model Control") PID Tuning capability (see here).
• Adjustable Peak Limiter for testing safety and to match large motors to small power supplies (or vice-versa)
• Valet Mode for the kids :-)
• Potentiometer Software Scaling (change your mechanical gearing without affecting your PID feedback behavior)
• Oversampling and digital filtering
• Rapid Response Capable (X-Sim→chibi-XSIM latency ≈0.006 ms)
• 500 Hz control loops nominal, with latencies of around 0.013 ms
• entirely hardware-based event-driven callback architecture
• could potentially drive very precise and rapid real time positioning solutions with demands well beyond those of a gaming application
• HAL drivers for a wide variety of peripherals (quadrature optical encoders, LCD displays, SPI, I²C and CAN bus interfaces, etc.)
• written for ChibiOS/RT v2.5.2

XSimCTRL is fantastic software written by Alexey Priladyshev used to help tune motion simulators. chibi-XSIM supports the XSimCTRL data stream protocol, so you can track your machine's performance while you experiment with various PID settings.

Screenshot:

Video:

chibi-XSIM also supports most third party data loggers with its ability to stream serial data output describing the performance of your running motion simulator. The free version of DAQFactory Express, for example, is ideal for this and has been used with success.

Please be cautious with the use of this very experimental software. I offer no claims as to the suitability or the safety of the firmware provided here in chibi-XSIM.

Is it buggy? Quite probably.

Does it work? Yes, but not a single motion simulator has been made with it yet that I'm aware of, so...

Could it hurt you? Yes!

Playing with powerful electric motors, home made contraptions and experimental firmware is inherently dangerous. If you choose to try chibi-XSIM, please be careful.

Motion simulator firmware has also been written for the new and exciting Electric Imp platform.

You can read about the zimple-XSIM project here.