I am having difficulty understanding the Bode diagram, which I have understood so far: that depending on the angle of the phase, where the system becomes unstable or stable.
I just don't know what the practical applications are when using this system in a closed loop.
I mean a practical example how to change the control, such as a robotic arm, or a mechanism that can be more sensitive (control)?
The BODE plot is a graphical representation of the frequency-dependent gain and phase of a circuit (amplifier, filter, control system,...). In this context, there are two fundamental cases as far as a system with feedback is concerned:
(1) BODE-Diagram for the closed-loop system. Here you can see if the sysytem can meet your requirements concerning gain, bandwidth, phase shift, attenuation (for filters),...
(2) BODE-Diagram for the open-loop system (open the loop at a suitable point and find the gain and the phase for all pars/blocks within the whole loop in series).
This function is called "loop gain". Now you can apply the well-known stability criterion. For this purpose, you must find the phase shift for the frequency where the magnitude of the loop gain is 0 dB. From this analysis you can derive the stability margin, which tells you if the closed-loop will be stable and how many "margin" the closed-loop system has until it will become unstable.,
In analog signal processing, the Bode plots show the gain response of a filter at various frequencies. This is helpful for confirming whether or not filters have suitable gain at pass frequencies and the proper attenuation at frequencies you don't want.
