Abstract: A control system for an automatic machine or robot having an articulated arm, comprising position transducers for sensing the position of the arm, actuators for effecting displacement of the arm and a mini-processor which receives signals from the transducers and feeds signals to the actuators, the mini-processor including a memory in which are stored digital data representing the movement of the arm, the stored data being memorized by the mini-processor at a selected frequency depending on the movement of the arm in a learning mode of operation of the machine, this selection being effected cyclically by sampling the transducer signal at a plurality of different frequencies and then calculating for each sequence of signals sampled at a frequency lower than a maximum frequency the values of the signals at points, interpolated between the sampled points, which would have been sampled at the maximum frequency: the calculated values are then compared with the actual sampled values at the maximum frequency and the

Abstract: A digital tachometer which can operate to count the revolutions of any rotating device for which an electrical signal the frequency of which is related to the speed of rotation can be obtained is disclosed. The tachometer includes means for `normalizing` the input signal to provide a pulsed signal having a predetermined relationship with the speed of rotation, main counting means for counting the pulses, and means for displaying the accumulated count. The counters are controlled by logic circuits to count for a predetermined counting interval and the digital display is updated at the end of each counting interval. In addition to the main counting means there are provided interpolation means for generating a signal representing the number of revolutions performed by the device under test in the interval between each successive pulse of the "normalized" signal, to improve the accuracy of the tachometer.