Lecture 32 : General procedure for dynamics equation forming and introduction to control
Typical Control system Configuration for Robot manipulator:
Excluding Higher level controller, the rest of system is same as that of typical industrial control system.Each axis of Robot will have this part of control sustem excluding higher level controller.Higher level controller generates commands and send it to lower level controllers. Higher level controller has to co-ordinate between various axes of robots.Now we will see controller design issues.
Controller Design issues:
Stability of controllers
:
It should have stabilty both in numerical implementation & actual performance.
Performance of controllers
:
As per application need, performance requirement should found out & depending on that decision on control strategy should be taken.
Energy required to achieve high performance:
It is the most important issue as there is upper limit on energy input to controller.
Types of Controller:
Proportional Derivative Integral (PID), Proportional & Derivative(PD), or Proportional & Integral (PI)
used in many industries
(not suitable for high performance applications).
Nonlinear(Most of systems in nature are non-linear).
Robust(to external/internal disturbances).
Adaptive ( adapt to system changes).
Neural network.
Fuzzy logic (example: washing machine).
Optimal(minimization of cost function).
Passivity based
First two are widely used in Robotics application which we will see in coming lectures.
Controller Design Steps:
Mathematical modeling of system.
A mathamatical model of system is defined as a set of equations that represents the dynamics of the system accurately or, at least fairly well. e.g. By using Lagrange's formulation we have derived mathmatical model for n-link Robot manipulator. Good understanding of Dynamics is needed to carry out this step. We will see different ways of mathamatical representation of the system in detail in coming part of this lecture.
Selection of control strategy.
Design of control parameters.
Simulation and experimental verification on actual system.
2nd & 3rd step & simulation part of 4th step we will see in detail in coming lectures.
