Which type of control system does not compare output with input for control purposes?

An open loop control system is characterized by its lack of feedback; it does not compare the output with the input for the purpose of making adjustments or corrections during operation. This means that once the input is set and the process begins, the system operates without monitoring the output to determine if any changes are necessary.

In contrast, closed loop systems use feedback to compare the actual output with the desired input, allowing for adjustments to maintain desired performance. Dynamic systems involve time-dependent behaviors and may still incorporate feedback mechanisms. Feedback systems inherently include the aspect of comparing output to input, defining their primary functionality.

Thus, selecting open loop as the correct answer highlights its distinguishing feature of operating independently of output measurements, which differentiates it from the other types of control systems.