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Belt-driving and a rotary encoder (going where no one has gone)


280Z28

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I don't have any idea what you are doing...but what about using a non-contact sensor instead? Hall effect sensors work nice for this sort of thing. I used a gear tooth sensor to sense steel blocks in an aluminum wheel (crank shaft sensor).

 

This may not have the accuracy you want though...just brainstorming.

Joshua

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I don't have any idea what you are doing...but what about using a non-contact sensor instead? Hall effect sensors work nice for this sort of thing. I used a gear tooth sensor to sense steel blocks in an aluminum wheel (crank shaft sensor).

 

This may not have the accuracy you want though...just brainstorming.

Joshua

 

It would need a minimum of 1000 teeth lol.

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That seems like an aweful lot of teeth for a crank sensor. Are you building your own system? If not, what system are you planning on running? It seems like a belt drive would be a VERY bad idea since it can stretch/etc. You need something diffinitivly aligned with your crank. Do you a tertiary as well, or are you using a cam sensor also?

 

Joshua

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I decided to add an FPGA to the system to offload the interpolated timing (needed when you use a 28 tooth, or any "low resolution" wheel) on dedicated hardware instead of taking up clock cycles on my processor. I have another thread in the Megasquirt forum about it, since it seemed like the best place to put general aftermarket ECU threads. :)

 

I am building my own system, yes. :)

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I guess I still don't see the reason to have such a high resolution encoder. I built an DIS system from scratch 2 years ago for my Master's project. I used a 4 "tooth" wheel on the crank, and a camshaft sensor. It used an 8051 based ucontroller. It was interrupt based of course, and used a lookup table with a custom word size to control coil charging and delay. I would be happy to send you my paper on the system if you are interested. It did have some unique bits to it that might be helpful (such as how to chargeand fire a coil reliably). If you are not interested, no problem!

 

Good Luck, that is a big project with demanding timing requirements.

 

Joshua

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I guess I still don't see the reason to have such a high resolution encoder. I built an DIS system from scratch 2 years ago for my Master's project. I used a 4 "tooth" wheel on the crank' date=' and a camshaft sensor. It used an 8051 based ucontroller. It was interrupt based of course, and used a lookup table with a custom word size to control coil charging and delay. I would be happy to send you my paper on the system if you are interested. It did have some unique bits to it that might be helpful (such as how to chargeand fire a coil reliably). If you are not interested, no problem!

 

Good Luck, that is a big project with demanding timing requirements.

 

Joshua[/quote']

 

I wanted to use the signal from it directly as the clock on my output buffer. :) It was a limitation my other processor/board was placing on me. :grumble:

 

The new board once it gets here will handle things with ease, as long as I don't run myself out of logic slices :lol:

 

I'd love to take you up on that offer on the paper. :)

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Your not going to turn that encoder with a belt drive are you? I couldn't understand if that is what you are asking. It needs to be connected through a gear drive or directly to the crank for position. Or a geared belt drive like a timing belt.

 

Besides the timing issues, I am not sure how well that encoder will hold up to a side load and RPM induced from the belt tension. Further, that is an optical encoder, which means if any dirt, moisture, grime, etc get in there, it may not like that much! I would reconsider using a hall effect sensor, they are much better for dirty environments.

 

I will PM you about getting that paper to you.

 

Joshua

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