Master-slave position and motion control system

An apparatus for effecting and controlling the motion of a load and comprising:

• (a) a master control system including a master actuator mechanically linked to the load for applying a force to the load, and a master actuator control connected to receive a reference input and control the master actuator to apply a force to the load responsive to the reference input to attain a desired value of a controlled motion variable in accordance with the value of the reference input;
• (b) a fluid power slave actuator mechanically linked to the same load;
• (c) means for generating a signal representing the force applied to the load by the master actuator;
• and
• (d) a slave actuator control connected to the master actuator force signal generating means to receive the signal representing the force applied to the load by the master actuator and connected to the slave actuator to controllably drive the slave actuator with a slave actuator force applied to the same load which is a function of the force applied to the same load by the master actuator, the slave actuator being operable to apply forces over a range from no slave actuator force when the total force applied to the load is within the operating range of the master actuator, to a slave actuator force whereby the slave actuator supplies most of the power of the motion.