CNC Cutting Machine Practice Test

What does an open loop feedback system fail to provide?

1. Corrections to the command signal

2. Speed control

3. Error detection

4. Force measurement

The correct answer is: Corrections to the command signal

An open loop feedback system is designed to execute commands without receiving feedback about the outcome of those commands. This means that once the system receives a command signal, it will process it to perform an action without checking whether that action is executed correctly or as intended. The core failure of an open loop system lies in its inability to make corrections to the command signal based on feedback received from the results of its actions. If there is an error in execution or an external influence that alters the desired outcome, the system has no mechanism to adjust the initial command to correct for that disparity. In contrast, a closed loop system continuously monitors the output and can make adjustments to align the results with the intended outcomes, providing the necessary corrections. This distinction is crucial in understanding the fundamental limitations of open loop systems as they cannot adapt to changes or errors in real-time operations. Other options like speed control, error detection, and force measurement can still be components or capabilities that might be present in specific contexts, but they are not inherently tied to the open loop structure's primary limitation regarding the lack of corrective measures. Therefore, recognizing that open loop systems do not adjust based on feedback leads to the understanding that they fail to provide necessary corrections to the command signal.