Semi-automation is a process or procedure that is performed by the combined activities of man and machine with both human and machine steps typically orchestrated by a centralized computer controller.
In this case, semi-automation may vary in its degree of manual and automated steps.
Semi-automated manufacturing processes are typically orchestrated by a computer controller which sends messages to the worker at the time in which he/she should perform a step.
The controller typically waits for feedback that the human performed step has been completed via either a human-machine interface or via electronic sensors distributed within the process.
Many manufacturers choose not to fully automate a process, and instead implement semi-automation due to the complexity of the task, or the number of products produced is too low to justify the investment in full automation.