Structure of robot control system

A robot control apparatus comprising:

• a plurality of servomotors which move preselected components of a robot, respectively;
• a plurality of position detectors which detect rotational positions of said servomotors and output the rotational positions in the form of serial data, respectively;
• a motor control driver which controls said servomotors based on the rotational positions detected by said position detectors and required positions, wherein said motor control driver detects an error in transmission between each of said position detectors and said motor control driver by checking a format of the serial data outputted from each of said position detectors, an error check code contained in the serial data, and a time required for the transmission between each of said position detectors and said motor control driver;
• and
• a serial communication path disposed between said motor control driver and said position detectors to transmit request signals provided by said motor control driver to said position detectors to request said position detectors to output the rotational positions, said position detectors being connected to said serial communication path in parallel to each other, respectively;
• and
• a storage circuit which stores therein the rotational positions detected by said position detectors in a cycle and a position estimating circuit which estimates the rotational positions of said servomotors based on the rotational positions derived in previous cycles when transmission between said position detectors and said motor control driver is in error in this cycle, and wherein said motor control driver controls said servomotors based on the estimated rotational positions.