PID

Posted 2020-10-15 smilingfrog

P - Proportional gain - stiffness and response 

　　Closes the loop, react quickly, according to the sign of the error

D - Derivative term - provides damping.  - if D is too large - causes vibrations

　　Structural resonances and distributed components (things are not perfect 

in nature) contribute to high frequency dynamics, which is amplified by too large D gain

I - Integral gain - Accuracy

  - Causes overshoots

  - Can cause instability

  - Larger I implies faster convergence

　　As long as there is any (even a slightest) error due to friction, the integrator keeps building up 

the control signal until it becomes large enough to overcome friction, and eventually makes the motor

rotate to reduce the error.

　　　　Low K_I → slow growing of signal (response delay)

　　　　High K_I → overshoot and instability 

source from courseware of university of moratuwa