Hi All,
I'm new to the group, so please be kind :)
I was reading Tim Wescott's article on PID without a PhD and it was very us
eful although it raised more questions in my mind. I then went over to Tim'
s website, which has an article called Z Transforms For Embedded Engineers.
The questions I have pertain mostly to this article, in particular to the
modeling of motors and how the resulting Z transform of the model is obtain
ed. So, here goes :

1) In Section 2.1 of the article, Tim describes a motor system and a result ing Z transform equation of the system. What I am trying to figure out is : Given an analog model of a motor system (and the corresponding physical pa rameters that describe such a system), what would be the process(es) availa ble to obtain the corresponding Z domain model of said system. Do different methods lead to better approximations, and under which conditions is it be tter to use one approximation over the other

2) In section 3.1 of the article, where Tim is describing a better filter, a second order filter model is presented. It would be helpful for me to und erstand the process of obtaining this model. For reference, the model eqn i s eqn (35). Also, why is this model preferred when not using a DSP ( see co mments above this eqn). Are there preferable models when assuming the MAC b ased instruction set of a DSP. I realize this article was written a while a go, so this may be a moot question given today's HW, but it did raise a que stion in my mind

I don't think I'm looking to be spoon fed here. If anyone knows of a good r eference that could answer these questions for me, that would be most appre ciated. And, if anyone has the in-depth knowledge required ( at least from my point of view ??) that would be required to answer these questions, then that would be most awesome.

Be Well

Victor

1) In Section 2.1 of the article, Tim describes a motor system and a result ing Z transform equation of the system. What I am trying to figure out is : Given an analog model of a motor system (and the corresponding physical pa rameters that describe such a system), what would be the process(es) availa ble to obtain the corresponding Z domain model of said system. Do different methods lead to better approximations, and under which conditions is it be tter to use one approximation over the other

2) In section 3.1 of the article, where Tim is describing a better filter, a second order filter model is presented. It would be helpful for me to und erstand the process of obtaining this model. For reference, the model eqn i s eqn (35). Also, why is this model preferred when not using a DSP ( see co mments above this eqn). Are there preferable models when assuming the MAC b ased instruction set of a DSP. I realize this article was written a while a go, so this may be a moot question given today's HW, but it did raise a que stion in my mind

I don't think I'm looking to be spoon fed here. If anyone knows of a good r eference that could answer these questions for me, that would be most appre ciated. And, if anyone has the in-depth knowledge required ( at least from my point of view ??) that would be required to answer these questions, then that would be most awesome.

Be Well

Victor