Which of the following is a key disadvantage of an open-loop control system?

The key disadvantage of an open-loop control system is the lack of feedback to correct errors. In an open-loop system, the output is not measured or compared to the desired set point, which means there is no mechanism to assess the accuracy or effectiveness of the output. This absence of feedback prevents the system from making adjustments based on real-time performance or external disturbances. Consequently, if there are any errors in the process or changes in system dynamics, the open-loop system will not be able to compensate, leading to potentially significant deviations from the desired outcome.

While increased complexity, higher costs due to multiple sensors, and less accurate performance over time could be associated with other types of control systems or specific configurations, they are not inherent disadvantages of open-loop systems specifically. The defining characteristic of an open-loop control system is its reliance on predefined inputs without adjustments based on feedback, making the lack of error correction a critical limitation.