What type of control strategy uses two or more distinct modes of operation?

Multi-mode control is a strategy that employs two or more distinct modes of operation to manage a control process. This approach allows for greater flexibility and efficiency in handling varying process conditions or requirements. Each mode is typically tailored to specific operational criteria, enabling the system to respond appropriately based on the current demands.

In multi-mode control, these modes can include combinations of feedback and feedforward strategies, or it may differ in terms of the control action being taken—whether the system is in a steady-state, during a transient response, or under load changes. By utilizing multiple modes, the control system can optimize performance and achieve desired outcomes more effectively compared to a single-mode approach.

Other types of control strategies, such as feedback control and proportional control, typically operate under a consistent method without the variation of distinct modes. On/off control is a simpler approach that merely toggles between two states rather than managing multiple operational modes fluidly. Therefore, multi-mode control stands out as the strategy specifically designed to encompass different modes of operation, making it the correct choice.