Joystick Sensors & Resolution

Generally there are four primary methods for determining the position of a controller, variable resistors (potentiometers), optical, hall effect, and load cells. Each of these sensors has advantages and disadvantages but first we want to look at what the data is and how the computer reads it.

8-bit, its a term that we have had from the early days of computer gaming, but what does it mean to controllers? Analog potentiometers have to be converted to a digital signal for the computer to understand. The devices which convert these signals will measure the amplitude and assign it a number which is then interpreted by the computer. Resolution is a way to understand how precisely this can be done. Resolution is viewed in terms of bits, so an 8 bit controller is seeing 2^8th power or 256 positions (0 to 255 or -128 to 127 depending on the controller) While not delving into sampling rates (a usb limitations we can encounter, or signal nose both of which can be read more about here), we can use resolution as a general way to understand how accurately a joystick will behave. If you were to draw a circle or even a diagonal with a joystick, you would see a series of steps as you do it. The higher the resolution of the joystick, the smaller these steps would be.

In the case of CH Products Fighterstick you would see 256 steps on the diagonal line because CH uses an 8-bit (2^8 ) resolution in their usb joysticks and throttles for analog axis.
Now lets draw the same diagonal line with a Thrustmaster Warthog stick, you would see 65,536 steps from corner to corner. Thrustmaster has chosen to pursue higher resolutions for their products, in the Warthog we see it using a 16-bit (2^16) resolution.
Now both are the flagship stick for their respected brand and both are known for quality, but one is not just double the resolution but nearly 65 thousand points more than double. Now there is discussion if the warthog truly is operating at 16-bit or if it is using oversampling to obtain it, regardless it doesn't matter in our case because none of us could really tell the difference in a simulator such as Arma or DCS. All we need to know is that it is ridiculously accurate and capable of incredibly smooth movements that are beyond the ability of a human to fully take advantage of. Our bodies are our weak link here.

While I love CH products for their durability and dependability, their lower resolution compared to competitors is their weak point. That's not to say that an 8-bit joystick isn't something that will work well in Arma or DCS, its just that it is not as good as it could be, nor as good as most of the competition. This is where resolution doesn't tell the full story, build quality and driver support can also play a big factor, not to mention the quantity and placement of buttons or how the grip feels to your hand. Now not all is lost for these lower resolution devices, the physical components in the CH Products' products are good, they just need something to allow their analog signal to be converted to a higher resolution digital signal. Thankfully the once very limited and specialized custom flight sim controller board market has started to give way to Arduino and Teensy boards. What used to cost $50 or more for a control board can now be done with free software flashed onto $5 Chinese control board giving you more axis and buttons than you will ever know what to do with. I'm going to be detailing more about this in another post discussing the conversion and updating of old gameport devices along with some more outlandish builds. Lets just say that I have the actual collective from an AH-64A Apache next to me at the moment and a delivery truck is on its way with a throttle which might just make me sell my Warthog throttle. If you are mechanically and electrically proficient, the sky is the limit when it comes to aircraft flight controls with these boards.

I'm going to follow this up eventually with more information about the types of sensor used in joysticks but for now I'm going to list out the resolutions to devices that I've tested so far.

CH Products:
Rotary potentiometers in just about everything, if it is a usb device it has an 8-bit resolution, 256 points on each axis, everything from pedals, to yoke, to throttle, to sticks have tested the same.

Logitech:
Wingman Force 3D: rotary potentiometer, this is an odd one that I need to retest at some time, I had torn it apart for a custom build and tested it by turning the pots by hand and found resolutions of 106 for the X axis, 150 for the y axis. Others who have tested them have found different resolutions from sticks purchased in different countries.

Microsoft:
Force Feedback 2: optical sensor, 10-bit, 1024 positions, for the x and y axis. 6-bit, 64 points, for twist. 7-bit,128 points, for throttle

Saitek:
Pro Combat Rudder Pedals: 10-bit, 1024 positions, for the rudder. 7-bit, 128 points for each of the brake pedals.

Thrustmaster:
T.16000m: Hall sensor 14-bit, 16384 positions, for the x and y axis. 8-bit, 256 positions, on the potentiometers for twist and on the throttle.
Warthog Stick: Hall sensor 16-bit, 65536 positions for both the x and y axis.
Warthog Throttle: Hall sensor 14-bit, 16384 positions, for each of the throttle arms (this however may not be totally true as only every other position was ever measured so it is likely a 13-bit resolution being doubled when fed to the computer). 10-bit, 1024 positions, for the "friction lock" lever, and for both the hall sensor x and y axis of the slew mini joystick in the right throttle. I have not taken the throttle apart to see what sort of sensor is used on the friction lock lever.

 

A shame I didn't know about this before I bought my CH gear, but at least I can rest easy knowing it will continue to work like brand-new for some time to come. I still feel confident that CH gear is overall a superior product than the Microsoft or Saitek stuff which won't hold up under long-term use (especially Saitek). I paid discounted about $150 for both the CH fighterstick & throttle and after using it, I feel like I got my money's worth. But there is no denying that the Thrustmaster stuff has much better precision.

Those VKB products look fucking cool as hell, btw. Are they pretty much a straight competitor of the Warthog HOTAS? From what I can tell, it looks like the Gladiator joystick has far less buttons on the joystick grip. That could be a potential problem...

 

The VKB is a competitor against/upgrade to the warthog, fixes some of the issues with the hog's gimbal system, and allows for changing out the grip. The standard grip currently is based on a WW2 german design (the KG12), there was previously one based on a Soviet era Russian fighter grip (used the Defender Cobra M5 joystick with VKB internals, it was sold as the black mamba by VKB until production ended last year), additionally you can install the grips from the thrustmaster cougar and warthog by way of an adapter if you prefer the american style grip. If I were not about to move half way around the world I'd be preordering their new floor base and stick as well as the adapter to use my warthog grip with it along with the Slaw Device pedal system.

 

Optical sensors have been done, Microsoft was the largest user of these back in their force feedback 2, but they are limited when compared to the resolution allowed by hall sensors. Unlike a mouse you are looking at a disk with openings spinning in front of the optical lens. Bottom line is that no one has managed to make one that can have as fine of a resolution as can be achieved though measuring lines of magnetic flux that a hall sensor does. There is always some slop when dealing with amplifying the movement of the stick to gain additional resolution for the optical sensor through gearing. That backlash in the gearing further makes it inferior to hall sensors. What you are looking at doing with changing resolutions on the fly is all done on the software side through adjusting the curves for each axis, or through using load cell based joysticks such as the aftermarket cougar bases an saitek's X65f. It's not a true change on the fly but you get most of the same effect through custom joystick acceleration curves.