Honeywell Sensors and MoTec M400

[peedpeed]

I am installing Honeywell Sensors (1GT101DC) to measure the wheel speed for Traction Control System purpose.

According to the Honeywell's manual, there is a specification for target (gear) of this sensor. But I have found that the target specification is quite flexible. It is stated only the minimum requirement for 'tooth width', 'tooth height', 'tooth spacing', and 'diameter'.

No number of teeth of the target is specified.

And since the input in the MoTec for the Traction Control System is only the voltage, I doubt how the sensors could detect the difference in pulses of the target and work with the MoTec ECU correctly.

How does MoTec know the wheel speed?

[Crispy]

Originally posted by peedpeed:
And since the input in the MoTec for the Traction Control System is only the voltage, I doubt how the sensors could detect the difference in pulses of the target and work with the MoTec ECU correctly.
How does MoTec know the wheel speed?

I'm pretty sure that is exactly how it works. The sensor sends a voltage to the ECU that ends up looking a bit like a square wave. The ECU senses the rise or fall of voltage and uses this to count the teeth. Once you tell the ECU how many teeth there are in one revolution, it can calculate wheel speed.

[peedpeed]

Yes, that is what I think at the first place. But I can't find any input of the ECU in the MoTec Software that asking about how many teeth there are in one revolution.

Thanks, Crispy
PP

[wagemd]

Originally posted by peedpeed:
Yes, that is what I think at the first place. But I can't find any input of the ECU in the MoTec Software that asking about how many teeth there are in one revolution.

Thanks, Crispy
PP

At least with the M4, there was a whole calibration method you have to go through. I think you roughly end up with pulses/mile.

[Tom W]

Page 18 onwards of FSAE day 3 advanced at the following link:

http://motec.com.au/downloads/downloadseminars/

[Poe]

I think the M400 has inputs for number of teeth and revolutions per km separate. It's been several years since I've used the software, but I remember it being in the sensor setup area of the software, not in the traction control setup. That's just going off of 3 year-old memory, though so you'll have to look around and see what you can find.

[Tom W]

I have posted a direct link that is currently being moderated...

If you are in a hurry though you can go to the motec com au website -> downloads ->seminar notes -> 'FSAE Day 3 Advanced' Page 18 starts the section dealing with launch and traction control.

For reference the sensor you are using is a hall effect sensor, this will give you a square wave with whatever number of teeth you have as the number of peaks/troughs in a single revolution. But hopefully you already know that as you specced the sensor.

Also be extremely careful that you manage the gap the teeth and everything else such that you only pick up the teeth you intend to. Not usually an issue on traction control systems, but something to watch for all the same.

[peedpeed]

Well, thank you guys so much. I really appreciate all of your replies.

So now I have to download the seminar notes and read through to find how to state the number of teeth in the software so that the MoTec ECU can calibrate the wheel spin.

PP

[Boffin]

There is data sheet on motec's website that details what input the sensor needs to be connected to (digital - either on or off)

From the ecu manager go
> In "Input Setup" tell which dig input is what wheel or axle and whether kph or mph

> Adjust>Digital input functions> Dig in #>Function: Change this to speed measure

> Then under parameters, set this up how you would like, remembering F1 brings up the help menu if you are stuck

[Nicky]

We use the M800. For the speed measure in the Dig inputs, the parameter->has a calibration. You need to enter the number of pulses for 100metres to display the speed in km/hr.

You need to take the circumference, number of teeth of the trigger wheel into account. Rest is just math.

[Nick Renold]

Remember to ask your suspension guys about circumference if you want an accurate velocity. The effective radius is typically different from what your tire spec says.