Question: Referring back to Problem 6.26, the mechanical inaccuracies in the open-loop positioning system can be described by a normal distribution whose standard deviation = 0.005 mm. The range of the worktable axis is 500 mm, and there are 12 bits in the binary register used by the digital controller to store the programmed position. For the positioning system, deter-mine

(a) the control resolution,

(b) the accuracy, and

(c) the repeatability.

(d) What is the minimum number of bits that the binary register should have so that the mechanical drive system becomes the limiting component on control resolution?

Problem: The worktable in an NC positioning system is driven by a leadscrew with a 4-mm pitch. The leadscrew is powered by a stepping motor that has 250 step angles. The worktable is pro-grammed to move a distance of 100 mm from its present position at a travel speed of 300 mm/min.

(a) How many pulses are required to move the table the specified distance?

(b) What are the required motor speed and

(c) pulse rate to achieve the desired table speed?