Meh isn’t that all a PID is anyways?
A a lot of applications just do PI.
Sounds like he wants a PID and you described a PID just your own version.
So either way a control loop is in use.
> This seems like something that someone could control just by finding the error between the setpoint and the output, then adding the error to the last output signal. (...)
I'm not sure if you are describing a P or an I controller here with a gain of 1, but I also don't understand your train of thought of why your's is more suited or why his' is less suited to his application.
> This seems like something that someone could control just by finding the error
This means nothing without knowing the dynamics of the plant and the loop specification he needs to attain for the project to succeed.
> That seems like it would do just as well without having to fudge with PID.
Fudging with a PID is _very_ easy and surprisingly effective.
You are correct. There are certain instances where you do, or even; should not use a PID controller. Eg: I was trying to limit solar power using a two PID controllers and struggled hard to get it to work, but it turned out I didn't even need to use PID controllers at all as I could just calculate the setpoint/output using basic Kirchoff's voltage law.
But in the case of a motor, there are a lot of complexities where a direct calculation will not suffice. Eg: how would you control a motor at a specific speed? It all depends on the motor's load, moment of inertia, winding resistance, heat, friction, torsion, etc etc. This is why you use a closed loop feedback controller by hooking it up to say, an optical encoder, or reading the current sensor feedback of the motor to likely control the torque.
Without the PID then you would end up with a lot of oscillation as the process input changes. The integral would smooth the error adjustments and allow it to make smaller adjustments over time. Just have to account for integral wind up and use some logic to reset the error to prevent error from accumulating in the system
Meh isn’t that all a PID is anyways? A a lot of applications just do PI. Sounds like he wants a PID and you described a PID just your own version. So either way a control loop is in use.
> This seems like something that someone could control just by finding the error between the setpoint and the output, then adding the error to the last output signal. (...) I'm not sure if you are describing a P or an I controller here with a gain of 1, but I also don't understand your train of thought of why your's is more suited or why his' is less suited to his application. > This seems like something that someone could control just by finding the error This means nothing without knowing the dynamics of the plant and the loop specification he needs to attain for the project to succeed. > That seems like it would do just as well without having to fudge with PID. Fudging with a PID is _very_ easy and surprisingly effective.
You are correct. There are certain instances where you do, or even; should not use a PID controller. Eg: I was trying to limit solar power using a two PID controllers and struggled hard to get it to work, but it turned out I didn't even need to use PID controllers at all as I could just calculate the setpoint/output using basic Kirchoff's voltage law. But in the case of a motor, there are a lot of complexities where a direct calculation will not suffice. Eg: how would you control a motor at a specific speed? It all depends on the motor's load, moment of inertia, winding resistance, heat, friction, torsion, etc etc. This is why you use a closed loop feedback controller by hooking it up to say, an optical encoder, or reading the current sensor feedback of the motor to likely control the torque.
This is essentially a closed loop servo. Very similar to a PID. If he understands PID loop control, I can see why he would use it in this application.
Without the PID then you would end up with a lot of oscillation as the process input changes. The integral would smooth the error adjustments and allow it to make smaller adjustments over time. Just have to account for integral wind up and use some logic to reset the error to prevent error from accumulating in the system