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1  Using Arduino / Motors, Mechanics, and Power / Re: Cable driven --> DC motor driven speedometer. Via Hall Effect sensor on: November 20, 2011, 12:42:39 pm
Wildbill. So that gives me 79751/60=1326 pulses per second at 100 km/h. This is beginning to look easier than first expected.

Zapro. I have a few steppers here, mostly 24 volts and a few DC motors I have pulled out of a cordless drill, the drill motor is fast enough.. And noisy as hell. Plus I don't like the fact is get pretty warm even running for 5 minutes. So will probably go with a brushless hobby motor as they tend to run cooler or find a 12 volt or less stepper motor for cheap.
With the right gearing and an ESC from the R/C world it would be doable.. I know the parts account for more than the sum of what I want to achieve.

Does anybody know how much torque a speedometer needs to function? I'm browsing this as i type: http://www.micromo.com/motor-calculations.aspx

But I will scrounge through my parts bin the size of my barn to find a suitable stepper or get one from a friend.
2  Using Arduino / Motors, Mechanics, and Power / Re: Cable driven --> DC motor driven speedometer. Via Hall Effect sensor on: November 20, 2011, 09:33:31 am
Terryking228, I have thought about using a brushless DC motor or stepper motor to drive the speedometer and that in turn drives the odometer. or going with a very small dc motor to turn the odometer. But I really wanted to retain the original look and feel of the car.
The rpm of the DC motor could be controlled by the Arduino on the fly by tapping into the hall sensor in the brushless motor.
Calibrating it would be done by calculating the wheel circumference divided by the differential gearing. This would yield the most precise result.

I know the standard circumference of the wheel is 1993mm the wheel speed at 100 km/h is 836.1 RPM and differential gearing is 3.07 which gives me 2566,827 rpm in the input shaft to the differential.
So the Arduino has to interpret the 2566.827 rpm which i will record off the rear ABS sensor. This has 31 teeth for every revolution, so multiplied by 2566,827 rpm that gives me 79751 pulses at 100 km/h. I do not know how fast an input the Arduino can take, I need to do some reading on the PWM input.

Scottyjr, I have looked at stepper motors but found them too noisy and bulky or lacking the power I need.

Stefan
3  Using Arduino / Motors, Mechanics, and Power / Cable driven --> DC motor driven speedometer. Via Hall Effect sensor on: November 19, 2011, 07:09:17 pm

Note: I have checked with the local authorities here in Denmark and it is legal to do this modification as long as the speedometer either shows correct or a higher speed than that which I travel, but illegal to render the speedometer inoperative.

So the project begins:

I have an elderly Mercedes W124 E300D that I am modifying with a newer electronic transmission out of a W210 E320CDI. I have a Powertraincontrolsolutions controller for the transmission, this will control the transmission itself, so that's covered.

Which leads me to my predicament. I cannot use the speedometer from the w210 model, as I have no clue whatsoever as to how to control CAN Bus or even feed it the correct signals.
I would like to retain the original speedometer/odometer, which was cable driven from the beginning. This cable snaked it's way from the original gearbox worm drive mounted on the output shaft. That output shaft is missing on the newer gearbox.

So I am in need to control a small DC motor based on the input of a hall effect sensor sitting in the rear differential, IE vary the rpm of the DC motor according to the frequency received from the sensor.
As to my knowledge, the Hall Effect sensor outputs a square tooth voltage from 0-5 volts with varying frequency according to the speed of the input shaft.
This would be fed via an input on the Arduino board, interpreted by it and then sending a PWM voltage to the DC motor either attached to the cable or directly to the instrument cluster itself. Depending on the noise I get from that motor I would opt for using the cable or shortening it somewhat and hiding the motor behind the dash encased in soundproofing or in the engine compartment in a waterproof box.

The reason I chose the Arduino is that I can counter driving with 18" or bigger wheels in the summer and going back to 15" in the winter, correcting as I go instead of having a speedometer that changes display
If possible and this is further down the road I would like for a small 20x2 LCD to sit in the speedometer housing and display some stuff, mainly oil temp, outside temp, boost,

I would even pay for the code, as I know sh*t about coding, and prefer to do the electrics and the mechanical part.

I'll get a quick and dirty diagram up over the mechanical parts and the electrical connections, so someone with a better mind can point me in the right direction.

Thank You in advance. * Spaceraver
4  Forum 2005-2010 (read only) / Scandinavia / Re: KonungR on: December 30, 2010, 05:35:40 am
Lækkert... Jeg behøver ikke vælte det danske kongerige for at få pointers.
5  Forum 2005-2010 (read only) / Interfacing / Re: W124 has to be electronical on: December 31, 2010, 05:50:58 am
Well. First off. I live in Denmark. If that means I break your laws then fine. It's not a problem here. smiley-grin

I am not talking about tampering with the speedometer for the sake of doing illegal things.
I don't have that much of a choice anyway. I need to drive the speedometer in some way or I have no speedometer at all.  :'(
I want it to read correctly when at speed and have the odometer read the correct value.
At some point I have to have another speedo in it, as the maximum speed it can show is 220 km/h and I am adding a large turbo to the car plus I have altered the gearing..
6  Forum 2005-2010 (read only) / Interfacing / W124 has to be electronical on: December 30, 2010, 05:37:17 am
Hi.
New to Arduino's and programming.

I have a car that I am modifying with a newer transmission that is electronic. I have a controller for the transmission, so that's covered. But am in need to control some servo's, a linear actuator and possibly a small dc motor.

I have no idea what type of Arduino I will need, which shield to use and how to program it. This is where I am asking for help.  smiley

But I will explain in detail what I am trying to do.
I am looking for a way to make the the car digitial to an extent.
Mainly making the speedometer and Odometer electronic instead of cable driven as it was born and remove the shift lever from the car gaining valuable space in the center console.
If possible I would like for a small 20x2 HD 44870 lcd to sit in the speedo housing and display some stuff down the road mainly oil temp, outside temp, boost, current gear.

For speedometer/odometer I have two options and the latter seems to be the easiest, although the noise made by the dc motor is unwanted which is why I am leaning towards the servo.
The servo has to move the speedometer needle via gearing to give me 320 degrees of rotation give or take.
Or I have to drive the whole Speedometer/Odometer arrangement with a small dc motor most likely with Pwm which is noisy and not so elegant in my opinion.

The linear actuator will pull and push the gear lever from park to drive in a normal fashion ie. P-R-N-D. Actuator is a digital servo that operates on 6-12 volts with a max power consumption of 3.5A and a control voltage of 3-5 volts, pretty standard stuff if I remember correctly.
Actuator link.
 http://servocity.com/html/heavy_duty_linear_servo__25__l.html

I would like to control the actuator with a rotary switch that has 6 positions, double row. So the switch would go P-R-N-D-M-TM.
The M and TM are Manual and True Manual. This only has to be told to the transmission controller and not the actuator.
For simplicity's sake assume that the actuator has to have the same position as D in M and TM mode. So the rotary switch only has 4 positions as far as the Arduino has to know, the remaining two will be electrically cut off from the Arduino with diodes, so the Arduino still holds the actuator in D.

So does anybody have an idea what I am in need of?
Thank You in advance. /me
7  Forum 2005-2010 (read only) / Interfacing / Re: Position control of a servo or stepper motor. on: December 30, 2010, 08:29:37 am
Im listening too here. Any luck with the gear by wire project??
I need something similar to your project, but do not have any experience with arduino's or programming.
Though I'll be controlling a 722.6 gearbox shifter from a Mercedes in a W124.
Just to lose the shifter.
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