Gear indicator based on gear position sensor or gear ratio

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Gear indicator based on gear position sensor or gear ratio

Postby ArT » Sun Oct 18, 2015 2:41 pm

I'd like to describe methods for gear position measurements. There are two popular solutions for gear indicator:

    1) based on analog gear position sensor 0-5V - this solution is dedicated mainly for motorbikes with stock gear sensor,
    2) based on gear ratio (rpm/speed) - this alternative solution has few disadvantages, but sometimes this is the only possibility to measure gear position without dedicated sensor.

gearIndicator.jpg (75.64 KiB) Viewed 8765 times

Re 1: Gear indicator based on analog gear position sensor 0-5V

Gear position sensor generates different voltage levels on output for each gear position. This is the most reliable and effective solution but unfortunately not possible in many cases. Sensor should be calibrated in UTCOMP settings. You need to enter voltage levels for each gear position, e.g. if you have 1V for 1st gear, 2V for 2nd gear etc. you should enter range instead of constant value, e.g. 0.9 - 1.1V for 1st gear, 1.9 - 2.1V for 2nd gear etc. This will make readings immune for noise, voltage fluctuations etc. Voltage ranges should be as wide as possible, but should not overlap each other.

gear-indicator_settings_utcomp_analog.jpg (64.13 KiB) Viewed 8776 times

Re 2: Gear indicator based on gear ratio

There is also possibility to calculate current gear from gear ratio ie. ratio of engine rotation speed (RPM) to vehicle speed (VSS). Each gear has different final ratio. Unfortunately, this solution has few disadvantages such as:

  • there are required accurate measurements for vehicle speed (VSS) and engine rotation speed (RPM) - if measurement resolution will be to low than gear calculations will be not accurate,
  • there is no possibility to detect reverse gear,
  • there is no possibility to calculate properly gear position during gear change - there is at least 1 second delay required for readings stabilize.

We need to calculate gear ratio ranges (instead of constant gear ratio) to make more reliable readings. There are few methods for it. The easiest one is to drive with constant engine rpm (e.g. 2000 RPM) and write down vehicle speed for each gear, e.g.

gear-ratio_calc1.jpg (40.68 KiB) Viewed 8776 times

We need to consider that our readings are not perfect. The measurement resolution is also limited. That's why we should extend these values and make gear ratio ranges, e.g. +/- 5%:

gear-ratio_calc2.jpg (54.34 KiB) Viewed 8776 times

Highlighted values should be entered to UTCOMP settings:

gear-indicator_settings_utcomp_ratio.jpg (59.79 KiB) Viewed 8776 times

Please note that ranges SHOULD NOT overlap each other. UTCOMP calculate gear ratio in real-time. If calculated ratio fit to any range, than UTCOMP will display gear number for this range. If it will not fit to any range, than it will display gear "N" (neutal position) - that's why we need to have "free space" between gear ranges.

Propably you will need to make few experiments before it will work properly. You can try to increase or decrease gear ratio ranges (e.g. +/- 7% instead of +/- 5%). Please note that it is impossible to get proper gear indicator during gear change. This method is not perfect but sometimes it is the only one possible.

Here you have excel for calculations:
(24 KiB) Downloaded 638 times

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Re: Gear indicator based on gear position sensor or gear ratio

Postby m-powergr » Mon Jan 25, 2016 12:18 pm

i have find a useful site for motorbikes

with that you can see the Gear Ratio the Final Drive Ratio and the Chain Pitch.

Speed in km/h related to Gear and RPM in (Stock-Current-Custom) Setup:

you can see that how much km/h in what rpm to calculate Gear Ratio (RPM/VSS)

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Re: Gear indicator based on gear position sensor or gear ratio

Postby Daily_Driver » Mon Feb 13, 2017 1:55 pm

Here is the gear ratio spreadsheet with expanded data. If you know your gear ratios, final drive ratio, and tire size it can calculate the necessary data for UT Comp w/o needing to drive the car.

To use it, input the desired RPM (such as 2000) for gears 1-6, then gear ratios 1-6, final drive ratio, and finally tire size. The form will calculate the rest. Fields where user input is needed are GREEN, fields with data for UT COMP are YELLOW.
Original spreadsheet with added calculation fields
(9.5 KiB) Downloaded 486 times
Installing the UT Comp Pro on my car

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