Complete novice to electronic circuit design and arduino programming.

I'm working on the design of a complete system to control the speed of a hydraulic motor, using a

This will be done using an Arduino Uno microcontroller, to drive the solenoid of a Bosch proportional valve (uses 5V)

http://www.hyprox.fi/datasheets/4WRE.pdf
(Link to proportional valve, size 6 to be used)

A speed demand signal will be obtained from a user dial (a potentiometer)

Speed feedback will be obtained from an optoelectronic pole wheel fitted to the output shaft of the hydraulic motor.

Proportional negative feedback will be used to control the speed of the motor.

Looking for help on: a circuit diagram/design, and also the sketches (code) for the Arduino relating to each function

Many thanks in advance for any help

 

I remember a long time ago controlling a small proportional valve using a National LM759.
IIRC there was an example circuit in the spec sheet, but showed a servomotor instead of a valve, but it worked great.
Max.

 

Not sure what this will be for? Knowing will help the members respond to you.

I am a software engineer enjoying this hobby. So with regard to the sketch I have some comments. Note that what you are asking for is not a quick task but rather will require several hours of programming.

Ask yourself a few basic questions as to the sketch requirements.

• How does one read a pot with an Arduino? This one is easy and I believe there is an example in the software for the Arduino. You have downloaded it? The IDE? I recommend running through at least the beginning tutorials on the Arduino site.
• What is the output of your speed sensor? Is it a voltage? Is it a series of pulses? Do you have to develop a circuit to use the slotted wheel in order to get an output?
• And finally, what is the process of proportional negative feedback? What input values are needed. What is the form of the output. I.e., PWM? An analog voltage?

If you can answer these and let us know what the answers are, we can help better!

 

I can tell you what I would give some thought to. I have never done this with an Arduino but have done similar PC applications. A Google of PID Control Loop Arduino seems to bring up[ some PID (Proportional Integral Derivative) code samples and ideas for Arduino. The basics:

From Wikipedia: "A PID controller calculates an 'error' value as the difference between a measured [Input] and a desired setpoint. The controller attempts to minimize the error by adjusting [an Output]."

So, you tell the PID what to measure (the "Input",) Where you want that measurement to be (the "Setpoint",) and the variable to adjust that can make that happen (the "Output".) The PID then adjusts the output trying to make the input equal the setpoint.

For reference, in a car, the Input, Setpoint, and Output would be the speed, desired speed, and gas pedal angle respectively.

Your valve seems to like a 2 to 10 Volt input or a 4 to 20 mA input. The problem is that Arduino does not have an analog out (DAC Out) but it looks like there are Analog Shields available, a Google of Analog Shield Arduino gets you started. As to your pulse signal for speed? I would convert that using Frequency to Voltage and this way have an analog voltage into your Arduino. You can use pulse in but I always liked scaling an analog to engineering units like RPM. Your command speed will be analog so may as well have an analog in for the speed feedback. Companies like Red Lion made nice turn key F to V converters, Omega Engineering and others also make them.

That is a rough of how I would approach this. I may have just used a controller rather than Arduino but whatever you want. There were cheap Chinese "process controllers" pouring in off the boat. You will be using the Arduino as a process controller. Just a few thoughts...

Ron