As embedded electronic control systems are increasingly penetrating vehicle subsystems, the designers are faced with a dilemma of providing state of art vehicle features on one hand and ensuring frugal implementation of the same to meet competitive pressures on the other. For embedded software and hardware systems this means adoption of judicious and innovative design choices with reusable building blocks. This paper dwells upon various design aspects of control and monitoring which are frequently used for automotive applications such as feed-forward and proportional integral control, diagnostics for sensor boundary conditions, handling of intermittent faults without causing nuisance to the vehicle users etc.
The paper elaborates the various design concepts involved by means of a case study of an electro-viscous fan control supported by field experiences and real-life insights. It evaluates alternate architectures for various design solutions and discusses how the optimal choice can be arrived at based on various performance metrics.
For control system architecture most of the automotive applications use proportional integral control. For ensuring a frugal implementation for the same paper discusses various algorithms for accessing multidimensional parameter maps, functional partitioning for closed loop control, re-structuring often used embedded C algorithms for consuming minimal CPU resources etc.
Control signals and field inputs need to be monitored and scaled ensuring they are fed to the control loop accommodating the system gains in both forward and feedback paths. A novel functional partition for implementing this operation is discussed ensuring resource efficient implementation.
At the end lessons learnt and novel concepts evolved are summed-up based on the real life field experience.