EPAS (Electric Power Assist Steering)

[David]

On a related note someone on a different forum suggested using an Agila column instead of the Corsa as it has a clutch rather than direct drive. Means that without assistance there should be no drag from the motor. Allegedly the same type of Mitsubishi ECU so the speed pulse setup (what ever you use) should be the same.

Only downside (as with any EPAS) then being the slight amount of movement from the torque sensor.

 

[Keith Stafford]

Got my Corsa C EPAS 'assistance controller' finished, I did not want to fit a knob on or near the dash!

My circuit has a 10 second delay upon start-up before it outputs any pulses, then it outputs a constant rev signal for the ECU to know the engine is running. it also outputs a low speed (high assistance) for a period of 1 minute, to allow you to 'unpark'. It then automatically reverts to the high speed (low assistance) until the button is pressed, which will give you 1 minute of high assistance, and automatically reverts to low assistance after the minute.

If you press and hold the button for 5 seconds it turns the circuit off, likewise if you press and hold for 5 seconds it comes back on again.

I managed to source the connector plug used on the Corsa C EPAS ECU. Let me know if you like what you see, battery is just there you give you a feel for the size, I have an ABS enclosure for it also.

 

[Robert May Eng.]

Just stumbled across this.Looks like it ticks enough boxes.

Bob

Corsa B C Electric Power Steering - Speed Related Controller - Automatic Control | eBay

 

[SteveB]

I have fitted one of the programmable controllers, easy to fit; then you program the speed that the maximum assist transfers to medium assist ( I set 10 mph) then set the speed to transfer to minimum ( I set 40MPH) That's it

If I had known how well this works it would have been a definite fit on the car when I built it.

Steve

 

[Ian Anderson]

Just stumbled across this.Looks like it ticks enough boxes.

Bob

Corsa B C Electric Power Steering - Speed Related Controller - Automatic Control | eBay

Hi Bob

Same unit I mentioned in post 35 above

Done by Phil Greewood???? who is the Megasquirt Guru in the UK

Ian

 

[Robert May Eng.]

Hi Bob

Same unit I mentioned in post 35 above

Done by Phil Greewood???? who is the Megasquirt Guru in the UK

Ian

Yes but now we have pretty pictures Ian I think I will go with one of these because Phil would not launch a product he was not happy with and that will be good enough for me. It goes to show its better to wait until you need these things because they just get better, this unit makes the cheapo ebay jobs look a bit primitive.

Bob

 

[Keith Stafford]

Got my 'push button' EPAS assistance adjuster circuit finished, "EasiPAS", no knobs, just a push button of your choice! The front of the '40s are light, so you'll rarely need high assistance. How mine works:-

After the 10 sec start-up delay the EasiPAS outputs, for 1 minute, a slow speed signal this will give you 1 minute of high assistance to manoeuvre, after which time EasiPAS will revert to the default state of high speed which puts the EPAS into the low assistance state (as if you are driving at 45+ mph). So you always have this low level of assistance.​

Next Project is a circuit to translate pulses from the wheels/shafts to the right rate to automatically adjust the assistance:-​

This circuit will allow the user to program the pulse count switching points, simply by placing the product in 'program mode' by pressing and holding the button for 5 secs, then driving to 15mph, pressing the button again, then driving to 45mph and pressing again. This tells the circuit to switch from high to medium assist at 15mph, then med to low at 45mph, base on the input pulse count from the sensor on the wheels or shafts. Of course you can decide you want the switch points to be 10mph and 30mph, just press the button at those speeds instead.​

 

[James Harvey]

Great stuff Keith. The next version with the ability to programme the level of assistance depending on speed soulds like the perfect set up to me.

 

[Malcolm]

The Corsa C system is used in the TVR world too. I am thinking of it for my Griffith project. One comment fed back from guys who have installed it is that it creates very light steering ie almost too much assist. They are now talking about using the control circuitry to reduce the input from EPAS to give slightly heavier steering. Not tried it myself yet but am interested to see how things move here. Another option used in the TVR world is to get a PAS rack and use an electronic steering pump. You can read about these mods on Pistonheads if you search the TVR pages.

 

[Keith Stafford]

I'll keep youse posted. The push-button product I have now delivers the lowest (high speed) assistance constantly, unless you press the (momentary) button, then you will get 60 sec of high (low speed) assistance, allowing you to park etc... I also allow the user to turn it off, with a long 5 sec push of the button. I had come to the same conclusion, that the '40 would not need high assistance, as the front would be light compared to the Corsa.

Malcolm, are the TVR guys saying it is too light at high speed, low speed or at all speeds?

The Corsa EPAS only has 3 levels of assistance, low, medium and high. If the low assistance is too much even at high speeds then manipulating the pulse counts won't cure it as you can't lessen the assistance.

 

[Bill Musarra]

While waiting for Keith to finish up the EPAS unit, I drove my 40 several times with the Corsa unit in without any assistance. I can tell you that is a perfect level while going at speed. I have just finished hooking up his EPAS unit on the car. I won't be able to test it on the road for a few weeks as the end of the garage is blocked with a paint booth setup. When I finish the first level of painting(rear clip) I will take it all out and give it a spin. I will compare the low assistance to "no" assistance. I definitely think the high assistance is needed for the slow go of pulling into the show parking areas, and backing out of the garage.
The one situation that I think the automatic function will come in handy is in stop and go traffic in the cities. Could be a pain to keep hitting the button every time you need to make a right hand turn????
Keith, would I be able to use the pulse output to the speedo(Stewart Warner) via a splitter and diode to keep feedback from one interfering with the other, or would I need another pulse counter? My pulse counter works off the bolt heads of the disc brake rotor.

Bill

 

[Keith Stafford]

Hi Bill, can you send me the details of the sensor, I don't really need info on the speedo (I think you sent it previously, but....) it may be fairly trivial to take the existing pulse and use it (very likely without a diode).

Alternatively we could reprogram the one you have to have the function like, long 3 sec press puts it into high assist mode another long 3 sec pulse takes it out of high assist, while a longer 6 sec press turns it off all together?

I would be interested to see how you get on, I have a feeling that the constant low assist will be sufficient for stop/start traffic, as the '40 is sooo light at the front!

 

[n wood]

Got my 'push button' EPAS assistance adjuster circuit finished, "EasiPAS", no knobs, just a push button of your choice! The front of the '40s are light, so you'll rarely need high assistance. How mine works:-

After the 10 sec start-up delay the EasiPAS outputs, for 1 minute, a slow speed signal this will give you 1 minute of high assistance to manoeuvre, after which time EasiPAS will revert to the default state of high speed which puts the EPAS into the low assistance state (as if you are driving at 45+ mph). So you always have this low level of assistance.​

Next Project is a circuit to translate pulses from the wheels/shafts to the right rate to automatically adjust the assistance:-​

This circuit will allow the user to program the pulse count switching points, simply by placing the product in 'program mode' by pressing and holding the button for 5 secs, then driving to 15mph, pressing the button again, then driving to 45mph and pressing again. This tells the circuit to switch from high to medium assist at 15mph, then med to low at 45mph, base on the input pulse count from the sensor on the wheels or shafts. Of course you can decide you want the switch points to be 10mph and 30mph, just press the button at those speeds instead.​

Hi kieth have you made any headway with your new next version with the ability to programme the level of assistance depending on speed,
i do like the sound of your push button one but one minute of full assist seems a bit long could you not make it so that you just press a button for full assist then press again to go back to low assist,
If you do manage to pull off the new version (and i hope you do ) will the price be less than what the other venders are asking for the programable type controller ie the TORQUE TEK EPAS ASSIST CONTROLLER that easysteer are selling.
cheers n

 

[Keith Stafford]

Hey Nigel, sorry for the delay in replying. The speed translation circuit is done and waiting on a colleague to program it. the main 'issue' is how we let the user program the speed mapping, that is, the translation of the speed pulse count to the EPAS count. If the speed is a fixed mapping, then we can pre-program is prior to dispatch.

I expect the first versions we produce (in about 4 weeks), we will pre-program them to whatever the user wants. the cost will be less (just) than the £100. do you know your mapping?

We have one of the Torque Tek units, it is massive and inside is an Olimex development board! Ours is about the size of small box of matches (remember them), same size as our EPAS controller:-

Corsa B, Corsa C - Kit - Electric power steering controller | eBay

Regarding the other suggestion you have, where you press to have low speed mode then press again to have high speed mode, yes we can easily do that, just let me know, if you want a special done for you.

Regards, K.

 

[n wood]

hi kieth what would the price of a push button type where you press for full assist then pres again for low assist ( you can pm about price if you want ) wish i had known you could do this before i bought one with an adjuster knob which ill be fitting this weekend but i can only see it being a pain in the ass keep turning a knob all the time,
a push button to operate hi and low assist sounds sounds like the best compromise to me i recon you could corner the market with that.
cheers.

 

[Keith Stafford]

hi Nigel, I need to speak to my microprocessor guy tomorrow to see if we can easily do it, if so then we would do it for the std price of £39 per unit. My guys is that you will end up using the knob in the same manner, full on or full off and nothing in between.

My main driving force to dev the product was that I did not want a rotary knob on the dash, a button is more in keeping with the GT40.

K

 

[n wood]

hi kieth ony just seen your post please keep us posted about it but i do think you will be onto a winner if you can pull it off like i said i think you would corner the market with such a setup as i would think a push button would also probly last longer than a pot as the pot seams to be the weak link from what ive read.
cheers.

 

[BruceA]

How about mounting a microswitch or 2 on the gearchange system? Either at the gearbox end or at the gear lever end? You could have one switch on First gear that would give max assistance, another switch on 2nd gear for the intermediate assistance and a tap off the reverse light switch that complements the 1st gear selection.

You then have max assistance in 1st and reverse, intermediate assistance in 2nd and minimum assistance from 3rd gear upwards.

Keiths system would require the appropriate inputs added to his design.

 

[SteveB]

I have used my EPAS system on the road and on trackdays since it was fitted. The result is just better than I could have hoped for.
Parking and reversing is just a delight and the feel at speed remains positive and no trace of vague or wander , through tight bends hairpins it knocks seconds off.
I have the torqetec unit that is quite big, however the programmable feature is all you need. After a few setups I have the high assist set up to 8mph ( bit difficult to get the system to accept lower) and mid assist drops out at 28mph.
The transitions are virtually undetectable. I cant imagine a need to make the manual changes, the result feels like a modern BMW or the like.

Steve

 

[Bill Musarra]

Bruce,
I think you may have hit on something there. As Keith's is Low, High, and Off, the switches could be high for reverse and first. Low for second and third and totaly off of 4th and higher. A microswitch(s) would work great and should be an easy do. The car needs virtually no assistance in the high gear ranges, so, an on/high at first, and a low, at second, and an off signal at fourth gear. Once triggered at first it would hold for reverse. the unit Keith sent me works on a one minute timer. So I could adapt mine to do just these things(I think). What do you think Keith?? Sure would automate things and wouldn't have to remember" to push the button".

Bill