Gantry cranes gain scheduling feedback control with friction compensation

To experimentally validate the theory, we had to compensate for friction. To this end, we estimated the friction, and then applied an opposite control action to cancel it. To estimate the friction force, we assumed a mathematical model, and then we estimated the model coefficients using an off-line identification technique, such as the method of least squares (LS). First, the process of identification is applied to a theoretical model of a DC motor with known friction coefficients. From this example, some guidelines and rules are deduced for the choice of the LS parameters. Then, the friction coefficients of the gantry crane model are estimated and validated.