How can I know that the high speed machine is working at the correct speed?

One of the output screens which can be chosen shows a trace of the velocity throughout the test. Sometimes there may be a very slight difference between the chosen value and the actual value represented in the trace. For example, a value of 1m/s may have been input but the reading from the trace is 0.98m/s. You can adjust subsequent tests to exactly 1m/s by inputting a slightly higher value in the set-up, 1.05m/s say.