CAN BUS Signals feed on Electric power steering ECU

[Chathuranga De Silva]

Hi everyone,

Is there anyone here have the knowledge of doing a electric power steering (EPS) conversion on a classic car ?

The issue is, in a normal ca, the EPS ECU adjusts the power assist according to the vehicle speed. Higher assistance at lower speeds (like in a parking lot) and lower assistance in high speed (like in highway cruise). This is done by the CAN BUS system in the car feeding the vehicle speed tk the EPS ECU.

But its obvious that classics dont have them and it needs a work around. There are modules available to buy in ebay that you can adjust the assist at you desire and not automatic. 

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F142461763061

However, what I am looking is for a workaround that feeds the EPS ECU with vehicle speed and do it automatically.

If a EPS unit is used from a non-ABS vehicle and if there is a way to feed the EPS ECU with vegicle speed with a vehicle speed sensor throigh some sort of a programme (Arduino, maybe ?) this can be achieved. 

Anyone here have knowledge of such ?

[kusumsiri]

Hi,

You may use a Arduino board with a GPS module. While Arduino getting speed from the GPS module, it can send a analog output to your EPS controller box. That is the basic idea came to my mind. But there are more things to consider in this case. Eg. for GPS module it may not provide correct speed in certain conditions like bad weather. If you like to read cars real speed, may use a speed sensor module for propeller shaft or such rotating arm. That will be another workaround. This will be a trail and error project.

Lets see other members thought too. Keep update the thread with your progress. Good luck.

P.S. Noticed that the ebay part provide only a controller box for EPS. It is not a complete EPS system.

[tilvin]

  On 10/26/2018 at 4:16 AM, Chathuranga De Silva said:

doing a electric power steering (EPS) conversion on a classic car

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What is the steering model in the classic car? Rack and penion, recirculating ball, worm and sector, etc....???

Whatever it is, keeping the ORIGINAL steering is good for you and car.....?. Rather than messing up with the steering, you go to GYM and get your body worked up. So you can turn the original steering easily.....?

[Chathuranga De Silva]

  On 10/26/2018 at 10:21 AM, tilvin said:

What is the steering model in the classic car? Rack and penion, recirculating ball, worm and sector, etc....???

Whatever it is, keeping the ORIGINAL steering is good for you and car.....?. Rather than messing up with the steering, you go to GYM and get your body worked up. So you can turn the original steering easily.....?

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It is a rack and pinion. Thanks for the advice going to the gym. ?

Still wanna do it though. Running a beefier set of tires and its a pia in parking lots ?

 

[Chathuranga De Silva]

  On 10/26/2018 at 9:55 AM, kusumsiri said:

Hi,

You may use a Arduino board with a GPS module. While Arduino getting speed from the GPS module, it can send a analog output to your EPS controller box. That is the basic idea came to my mind. But there are more things to consider in this case. Eg. for GPS module it may not provide correct speed in certain conditions like bad weather. If you like to read cars real speed, may use a speed sensor module for propeller shaft or such rotating arm. That will be another workaround. This will be a trail and error project.

Lets see other members thought too. Keep update the thread with your progress. Good luck.

P.S. Noticed that the ebay part provide only a controller box for EPS. It is not a complete EPS system.

Expand  

Thanks Kusumsiri,

 

GPS was one of the options but nor reliable, bad weather and your speed sensor says you are not moving when actually you are on highway doing 100 will be chaos.

I was thinking about having something like this. This nifty thing just sits around your speedo cable and sends the vehicle speed . But this guy will speak in Russian while the EPS ECU talks only Hindi (IYKWIM) ?

Hoping someone here know the interpretation strategy between the languages through a Arduino box. If not show me a route at least so I could go and seek. 

Yes, the ebay link has only the module. There are others products which has all the components. But I already got them.

[ajm]

you need a circuit which would convert the wheel speed into a voltage that corresponds with the voltage curve  adjusted by the knob.

Easier said than done because

1.wheel speed of wheels can be different depending on if the vehicle is turning,so which wheel speed to select?

Assuming you got the wheel speed issue sorted out,

2.what is the correct assistance level for a particular wheel speed  so that it would feel natural?

(too much or too less assistance can be un-natural and the former can even lead to an accident)

 

If you only need a solution during parking, then a manual system like this would be best IMO.

with an additional feature to cut power supply during speeds>20km/h or something might be semi-automated digital solution(only If the EPS column does not generate unnecessary resistance when not powered)

Good luck and let us know how it went!

 

BTW this might be a simpler solution if it works.

https://americanpowertrain.com/i-8580036-ez-electric-power-steering-for-street-rod-and-customs.html

 

Edited October 26, 2018 by ajm

[Chathuranga De Silva]

Thanks ajm for the insight.

From what Ive read (painstakingly for over a month now) wheel speed sensing is a big no no in make-shift EPS. But its exactly how its done on a ABS powered vehicles. But then I will have to put an ABS unit as well. Too much trouble in that road.

Im trying to see if someone would have that knowledge of figuring out how to let them talk to each other. Between Speedo cable speed sensor and EPS ECU.

But then Ive read there usually two feeds to the EPS ECU at different bandwidths in order to avoid any incorrect feeds.

Manual systems suck because, what if i forgot to turn it off and I get some crazy assist doing 80 on the highway ? 

But what you suggest is nice. Cutting off the assist after a certain speed. No one needs assistance after a certain speed. Will see about that.

[Chathuranga De Silva]

  On 10/26/2018 at 12:07 PM, ajm said:

BTW this might be a simpler solution if it works.

https://americanpowertrain.com/i-8580036-ez-electric-power-steering-for-street-rod-and-customs.html

 

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It is, but, expensive and they are using the same core units such as made by koyo, jtekt or denso.

Speed sensitive option is the lovely feature they have though

[ajm]

  On 10/26/2018 at 12:27 PM, Chathuranga De Silva said:

Im trying to see if someone would have that knowledge of figuring out how to let them talk to each other. Between Speedo cable speed sensor and EPS ECU.

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This looks like just analog inductive sensor,isn't it? The speed has to be processed to a digital signal which the EPS computer can understand. Which signal type depends on the EPS unit you select. It could be frequency,PWM modulated or both. Or if its a new EPS, might have a serial communication interface which can be CAN,LIN,SENT protocol or something unique to the EPS manufacturer. It might even require special permission from Another computer to be activated, since steering is a safety critical function. It would be better to select one of the very early EPS, since such additional features will be much less.

[Chathuranga De Silva]

  On 10/26/2018 at 1:53 PM, ajm said:

This looks like just analog inductive sensor,isn't it? The speed has to be processed to a digital signal which the EPS computer can understand. Which signal type depends on the EPS unit you select. It could be frequency,PWM modulated or both. Or if its a new EPS, might have a serial communication interface which can be CAN,LIN,SENT protocol or something unique to the EPS manufacturer. It might even require special permission from Another computer to be activated, since steering is a safety critical function. It would be better to select one of the very early EPS, since such additional features will be much less.

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Yes ajm,

Im using a new EPS column with an early ECU. EPS Column is like all the same from the begining of time ? Just four wires going in. But i have an early column as well if anything goes wrong in the initial testing.

The speed sensor gives an analog signal and needed to be converted, like you said (You seemed to know your stuff ? )

Toyota Yaris 2004-2007 wo ABS is the right candidate.

[ajm]

This looks right since not so advanced.The thicker wires are power supply or also motor control output signals? Whats on the other side of PCB,you have a photo?

First need to confirm what type of speed input is used, analog,digital,serial..in order to confirm before fitting if it works at all,you have to Provide a suitable impulse to the sensor input and see if the motor responds.

[Chathuranga De Silva]

This is the one I have for now, i took it while a quick peak inside, Ill get a better picture of the PCB and post it here.

Yes thicker wires run to the motor.

[youngerk]

Nice work everyone but no final answers yet .

I have the 2011 to 2018 Toyota Yarris EPS NCP30 .Can any one help with ECU wiring config . Colors are red ,white,light/green,and green.

Ive looked at a number of web pagers but can only find the 2007 Toyota yarris 

This has being fitted into a 1971 XY Falcon which is very similar to a mustang I can share the spline details if any one is keen.In New Zealand we are not allow to weld any part of the steering system . So to pass a certification it have to be a billet part machined from one piece off steel.

 

Any way Thanks 

[vag2]

how are you planning to send speed input to the EPS?

 

[youngerk]

Good point .First off will the EPS work in limp mode as a starting point . But still need to know the wiring connections .After that the speed signal needs a voltage pules which I can create via an instrument Bemex just for testing purposes .But again I need a starting point eg 5 volts to 11volts as an example.

Any one got experience or ideas ?

[vag2]

there are kits available with the signal generation unit and sensors for the motor control. It would be easier and safer than trying to do by yourself since you are asking for suggestions here.

https://www.ebay.com/motors/blog/convert-your-classic-to-electric-power-assist-steering/

 

Edited May 3, 2020 by vag2