DIRECT ADAPTIVE CONTROL SYSTEM
in direct adaptive control system estimated parameters are directly used in adaptive controller.it means that the controller parameters are directly adjusted by the adaption techniques. it eliminates the need of plant parameters adjustment.
INDIRECT ADAPTIVE CONTROL SYSTEM
in indirect adaptive control plant parameters are indirectly estimated values which are used to controller parameters.indirect adaptive control is also known as plant parameter adaptive.
the performance of the control system is affected by following factors
1.un-predicted variation of the process parameters.
2.disturbances acting upon the performance of control variables.
CONVENTIONAL FEEDBACK V/S ADAPTIVE CONTROL SYSTEM
1. conventional feedback control system is mostly used to verify the disturbances that are hold by the plant due to environmental condition. the output exhaust through the plant must be compare with the input command and accordingly error signal is generated by the feedback control system which is further feed to the controller.it reduce the effect of disturbance on the controlled variables.
adaptive control system also follow the same technique but the difference is that in adaptive control system instead of controlled variable , the index of performance(ip). this is mostly used for maintaining the performance of the control system in the presence of parameter disturbances. in adaptive control system first we measure the index of performance of the system and then compare it with the desired ip (index of parameter) and their difference is then fed to the adaption mechanism.the output of the adaption mechanism is further used to modify the system performance.
adaptive control system can also be understand by a schematic shown below.