Hi All
I wanted to thank H1TMAN_ACTUA1 for making a comparison of rudder pedals. Due to price of both pedals I never thought someone will buy both and compare :-) Now I'm glad someone did.
I belive review is honest opinion from a user perspective, not going into technical details about sensor type.
I also agree with a few statements here, that such resolution cannot be percieved by a human leg. My belief is that very well trained Human leg can only make precise movements of about 2000 positions across rudder movement range...that is why reviewer did not notice any difference while flying...if there is any difference anyway.
About sensors and electronics.I've seen a lot of writing about electronics and sensors here, so I want to make a few clarifications.
MFG Crosswind rudder pedals still use:
- GVL224 electronics , a proven manufacturer also producing for Baur BRD...reason why I choose him is because his device is already sucessfully used over 3 years now without complaints.
- Rudder axis - Analog magnetoresistive senosor KMZ41 - implemented on main PCB
- Brake axis - Analog Hall sensor Allegro A1302
- Since 01.10.2013 Firmware and software for pedals is produced by MFG team, while GVL224 provide only electronics
In a few words...komaroff did a honorable job of producing digital sensor, but it is NOT better, or worse than my existing analog sensor. I never tried Komaroff sensor myself, and I don't know what actual magnetoresistive sensor and signal conditioning IC komaroff use...but I can tell such statement on the following arguments :
- Komaroff probably use same analog KMZ41, but with signal conditioning IC that provide digital 3 wire PWM output
( possible that I'm wrong, and komaroff use Austrian microsystems sensor, type I can only speculate since it's not published).
In any case...whatever sensor Komaroff use...It probably was on my testbed during last year. I've tried industry finest solution for development of my own electronics and I can tell you a few words about it :
- I did not find sensor with precision capable to sense any better than 0.022 degree of rotation...no sensor can do that. Transfered into raw positions in windows...this mean 45,45 values per degree of rotation.
Now...let's get back to mechanical design of the pedals to see how this compares. I give you a simple drawing
Purpose of this picture : Assuming both mechanical pedal styles have EQUAL WIDTH, and EQUAL RUDDER RANGE,...design with narrow parralelogram principle - like MFG Crosswind - has almost DOUBLE rotation on rudder axis
Now...let's get this into REAL RESOLUTION ACHIEVED BY BEST SENSORS IN THE WORLD, IN OPTIMAL CONDITIONS
MFG Crosswind rudder principle = 34 degree x 2 = 68 degree x 45,45 positions = approx
3090 TRUE POSITIONSOther style rudder pedals ( baloo, slaw, simped etc.) = 18 degree x 2 = 36 x 45,45 positions = approx
1636 TRUE POSITIONSNOTE : I'm not claiming that my pedals rotate 68 degrees, or that slaws rotate 36 degrees... I draw IMAGINED characteristics of both pedal style to clarify importance of mechanical design.
Don't forget that I've just revealed one of many secrets that MFG Crosswind design has in it's sleeve...just for clarification purpose. I hope it's secret well published.ANALOG VS DIGITAL
Which one is better depend on a purpose of a sensor and sensor distance from ADC ( analog to digital conversion ).
In a perfect enviroment there is no difference, but analog signal can pick up noise on it's way to ADC if there are possible disturbances...so if signal travel longer distance - digital is better ( MFG pedals sensor is on PCB..therefore travel only few centimeters, brake sensors use best quality shielded cable)
Digital also has advantage over analog in cases where sensors are powered with unregulated voltage because voltage drift will also affect sensor reading - solved by supply voltage regulation
However, nothing can beat the speed of analog signal and a fast ADC chip
For the purpose of comparison...every sensing element...hall or magnetoresistive...is measured in Analog domain, goes trough Analog to digital conversion ( ADC) and in trough some sort of signal conditioning threatment...le't draw a simple flowchart of that magnet position to our joystick reading conversion
Gain amplifier : used to amplify signat that hall or magnetoresistive element pick up. Most sensors have it fixed so such sensors have FIXED MAGNETIC SENSITIVITY. Some sensors can program Gain in factory, or even reprogram gain amplifier strenght "on the fly" ( like MLX 90363 )
MCU - Microcontroller, main chip to communicate with USB...can be poor or a solid good one, can have integrated various functions such as 10bit, 12bit, or even 16bit ADC unit, other communication protocols for digital sensors, buttons, etc.
ADC - analog to digital converter
DAC - digital to analog converter
PWM - pulse width modulation
CLASSIC HALL SENSOR ( Allegro A1302 or similar)
Hall element - gain amp. - ratiometric or linear voltage output ( analog) - ADC - Signal conditioning (on MCU) - USB output
Classic automotive setup KMZ41 magnetoresistive sensor - analog output
dual magnetoresistive bridge - 2x signal analog output ( sine and cosine) --- //chip with gain amp., ADC - conditioning - DAC analog output // ---wire ---- ADC( on MCU) - USB output
Classic automotive setup KMZ41 magnetoresistive sensor - digital PWM output
same as analog, but signal output from signal conditioning chip is not analog but 3 wire PWM signal...so there is no ADC conversion on main MCU
Alternative setup for KMZ41 - rely on usage of smart, powerful MCU
dual magnetoresistive bridge - 2x signal analog output - 2x gain amplifier - 2x ADC input on main MCU - powerfull signal conditioning on main MCU - USB output
There are other sensors , like NXP KMA200 magnetoresistor, or Melexis MLX90363...which have both sensing element, gain amplifier, ADC, signal conditioning on a single chip...and can give analog, PWM or SPI output toward MCU.
SPI is very intresting protocol. It is also DIGITAL, but these sensors can also communicate in BOTH WAYS....so signal is not just OUTPUT...but main MCU can communicate and change settings directly ON SENSOR.
There are other possibilities, but I will not complicate things even more :-)
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MAGNETORESISTOR VS. CLASSIC HALL ... magnetoresistor is better in most situations
MAGNETORESISTOR VS Melexis 3d Hall ---- MELEXIS IS BETTER !!!!
Reason is very simple. While magnetoresistors do measure angle of magnetic field, which is better than classic hall, they output signal using fixed gain amplifiers. However...signal output values CHANGE WHEN MAGNET DISTANCE CHANGED !!!!...which make magnetoresistor very sensitive to mechanical tolerance of a device
MELEXIS 3d HALL technology is BETTER as sensory is truthly smart. It has automatic gain control. It has multiple hall elements to measure magnetic field trough three axis. For example...if magnet distance changes sensor will only pick up more or less noise...but actual output values WILL NOT CHANGE !!!
Due to built in formulas for compensation it is also better for DIY..as it tolerate more misalignment of magnet and sensor
It is possible to use stronger magnets at only 1mm distance from sensor. In that case automatic gain will be automaticly reduced to minimum...so sensor is less likely to pick up magnetic disturbances than other sensors...my test show that in such setup MLX90363 sensor don't pick up disturbance of a moving M10 bolt on a distance of only 3 cm !!!!...mission impossible for other tested sensors.
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You probably guessed it so far....that I've chosen digital sensor MLX90363 for my new electronics which should be ready soon.
My choice for a such Next generation sensor is because it can also serve in various other situations...Joystick for example :-)
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I already see a question comming up something like :
What is the difference of MFG Crossind pedals with New Digital sensor VS current magnetoresistive sensor ??
Answer is : almost NONE !!!!
To explain myself. New digital sensor MLX 90363 has built in automatic gain, temperature reading, noise filtering, hysteresis filtering, also smaller non linearity error on a sensor itself...can read angles up to 360 degrees...but what does that all mean for end user of MFG Crossind rudder pedals - NOTHING...since these features are already built in my current firmware. If you followed how sensor to USB workflow is going...you probably guessed it right...very powerfull MCU does all the job for analog sensor...while next gen digital trixis hall does it all itselff, unleashing the power of MCU for other operations
Truth be told.... I AM THE ONE TO BENEFIT FROM NEW SENSOR BECAUSE :
- I will not have worry about centering magnet as I do now :-)
- no worries about small magnet displacement - now I have to be very carefull
- no worries about magnet distance...now I need to be very very very carefull about that :-)
END user...will not notice digital VS analog sensor...won't see a difference
Happy simming to you all
Milan