Need some logical help with structures

Using Arduino Programming Questions
#1

I have an application in which I will be controlling the position of several DC motors as if they were servos. Ultimately, this will end up in a library. I want to create a nice structure to the motors to treat all properties the same and to make it universal.

Here is what I have:
7 motors that will use an external ADC
1 motor will use an internal ADC
2 motors will use an optical interrupter and limit switches

Common properties I can see among them:

LUPin (forward pin)
RDPin (reverse pin)
Chan (the channel of the motor, but this would really be known by the struct array, right?)
Dir (value for direction: Stopped = 0, forward = 1, Reverse = 2)
Currpos (current position of the feedback)
pos (last commanded position)
Min (minimum position value)
Max (Maximum position value)

Not common:
External ADC channel
Internal ADC channel
Encoder (pin used for the optical interrupter)
LU_LIM (pin - limit switch for one extreme)
RD_LIM (pin - limit switch for the other extreme)

To make it truly universal, there should also be properties such as:
Speed (PWM value)
EncoderA (for quadrature encoders)
EnablePin (if used, some controllers do)

Ultimately, I would like to provide a library that allows for different types of motors and feedback to be controlled as servos. I probably don't need to flag what type of feedback, and instead just rely on the main code to handle that and just update currpos in the structure. Given that, it probably makes sense to store the feedback related stuff (pins, channels, etc..) in a separate array managed by the end user.

So, I guess I am looking more for logical help than I am in actually creating the structure (I know how to do that part) and whether a structure is the right thing to use for this.

I'm sure I missed something important, but I will leave it here and hope for some questions, suggestions, or feedback.

#2

It seems that the method of sensing position is going to vary, so I would separate that from the basic servo. What I'd do is define a base class representing an abstract position sensor, and concrete classes representing specific types of position sensor - with the external interface defined entirely by the base class. Then define a servo class that is constructed or configured with the position sensor instance (and pin numbers, properties specifying the required behaviour and so on).

You will need to implement a feedback loop of some sort. You could use a simple proportional feedback, but for only a small amount of extra effort you could use a PID feedback algorithm. If you anticipate playing around with different approaches then I'd use a class hierarchy here too, with the abstract base class defining the common behaviour and concrete classes implementing the implementation-specific behaviour.

#3

I guess I have some researching to do. I understood about 60% of what you said. At least the intent itself was clear. Just having trouble picturing it in my head.

Thank you!

#4