I'm new and just started looking at using the Arduino to control my electric power steering pump.
I'm converting a Ford Focus to an electric vehicle and plan to use an MR2 electric pump to provide power steering.
I want to use the analog data provided by the vehicle speed sensor.
Is the following possible for a newbie?
Using the vehicle speed sensor (VSS) have the power steering pump (12volts) be on full power when the vehicle speed is under 30 mph and then have the pump reduce its power as the speed increases to off when above 50 mph.
Also, has anyone used the Arduino to allow the vehicle fuel gage show voltage of a battery (or battery pack).
Thanks for any ideas/suggestions you might have.
So you want to make it impossible for the driver to steer well when he is going above 50 mph? Are you certain that is safe? My gut feeling is that it can't be that safe...it doesn't sound safe...?
If you're looking to read the vehicle speed you should probably dig right in to interfacing with the OBD; I've seen a lot of projects using an Arduino to interface with it. Google is your friend
cr0sh:
So you want to make it impossible for the driver to steer well when he is going above 50 mph? Are you certain that is safe? My gut feeling is that it can't be that safe...it doesn't sound safe...?
I know power steering and brakes are designed to decrease as your speed increases (to keep quick movements from locking the wheels up), but I don't know if it ever fully turns off. As someone that has lost the power steering in a vehicle while it was moving - twice - this seems like a bad idea.
Sounds a bit like an application for a Darwinian award.
What method are you using to give the driver "feel" from the steering if it's powered by an electrically driven pump. Perhaps you'd be better salvaging a ready-built system from an old vehicle and incorporating that into your build. That way you'll have the comfort of knowing that the ergonomic problems will have been ironed out by others before it's too late.
I'm not reinventing the wheel. I am using a hydroelectric pump from an MR2. There have been a lot of conversions using this and other electrical pumps. I was wondering how to use the Arduino to regulate pump speed based on speed of the vehicle.
I was wondering how to use the Arduino to regulate pump speed based on speed of the vehicle.
Just like you'd drive any other electric motor at varying speeds. First, you get a motor controller that is compatible with the voltage and current needs of your motor.
Love the comments of the authorities in the field...
Typically the steering forces are highest at low speeds because that is where you use the largest steering inputs. At higher speeds you use very small sterring inputs, to correct for position i the road, as large inputs would move you across lanes, and not just in your lane. At speed your inputs are just corrections and are generally not enought to open the valve in the steering gearbox and the power assist does nothing. At low speeds you are doing things like turning the steering wheel to the locks for parking and driving around a parking lot. he assist is very important there as you are putting large inputs and need rapid steering movement to put the car in the parking space.
If your power steering were to fail at 70MPH you would hardly notice it, but it would be a major problem trying to change lanes at 10MPH.
Braking, on the other hand needs to be very effective at high speeds, otherwise you could never slow down. At lower speeds it can be less effective as there is less energy to get rid of.
I think it depends on the type of steering rack. I've driver one car with PAS with the pump completely removed. The steering was pretty heavy due to the sticky tyres and aggressive camber, but the rack itself worked just like a manual rack. But I've seen another car with PAS where the steering rack seemed to lock solid when the PAS failed. It was possible to turn the steering - just - but it was dramatically harder than an ordinary unassisted rack would have been.
The MR2 pump is a 12volt pump which provides pressure to a power steering rack. My Focus had power steering provided by a belt driven power steering pump. I plan to use the MR2 electric pump to replace the belt driven pump. What I'm looking for is assistance/ideas on controlling the pump output based on vehicle speed. My manual transmission has a Hall Affect Vehicle Speed Sensor which provides input to the vehicle Power Control Module. I would like to use the Arduino, tap into the line from the VSS, connect to the pump to control pump speed...thus reducing or increasing hydraulic pressure based on the vehicle speed. Can I connect the VSS input directly into Arduino (I believe it is 0 -5volts)?
If the signal is 0-5V then it's safe for the Arduino. Try using pulseIn() to see if it provides an accurate reading for the speed.
Y'know what you really need is a torque sensor on the steering column. You could measure the torque applied on the wheel and power up/down the hydraulic motor accordingly.
Also, don't forget that your pump is a vane pump. Unlike what you'd see with a gear pump the pressure might drop off in funny ways if you try decreasing power to it.
We can all thank Smokey Yunich for variable rate power steering. Yes, the faster you go the less power steering you need. My last car didn't even have power steering and the only time you would notice is while parking.
Fords, that I've been under, often use an exciter ring setup with a sensor for wheel speed to control the ABS. That might be an easy way to find wheel speed.
Is your plan to dump the whole power train or keep the transmission / differential?
I do wonder, because I don't know, how the Toyota pump varies it's boost? Is it done with pump speed or valving?
