Luca Simoni

Friction modeling with temperature effects for industrial robot manipulators

In this paper we present a new friction model for industrial robot manipulators that takes into account temperature effects. In particular, after having shown that friction might change very significantly during robot operations, two solutions based on a polynomial description of the joint friction are proposed and compared. In both cases the models proposed do not need a measurement of the joint temperature, but just of the environmental temperature, so as to be easily applied in industry. Experimental results demonstrate the effectiveness of the applied methodology.

A Hardware-In-the-Loop setup for rapid control prototyping of mechatronic systems

In this paper we present a Hardware-In-the-Loop setup for the simulation of complex mechatronic systems. The setup consists of two coupled brushless motors. One of them is the motor under test, which is used to design the control algorithm and to test the control software, while the other one simulates the device to be controlled. Libraries of mechanical and hydraulic components have been implemented in an IEC61131-3 language so that a complex system can be simulated in a relatively easy way and this allows for a rapid control prototyping. Practical issues are discussed and an illustrative example is shown to confirm the effectiveness of the setup.

Modelling the temperature in joint friction of industrial manipulators

In this paper, a new model for joint dynamic friction of industrial robot manipulators is presented. In particular, the effects of the temperature in the joints are considered. A polynomial-based model is proposed and the parameter estimation is performed without the need of a joint temperature sensor. The use of an observer is then proposed to compensate for the uncertainty in the initial estimation of the temperature value. A large experimental campaign show that the model, in spite of the simplifying assumptions made, is effective in estimating the joint temperature and therefore the friction torque during the robot operations, even for values of velocities that have not been previously employed.

Multi-frequency disturbance compensation in a plastic injection molding machine

In this paper we present a strategy developed to compensate for multiple sinusoidal disturbances affecting the pressure output of an industrial revamped plastic injection molding machine. The method is based on the suitable implementation of an adaptive feed-forward control technique and has the characteristic that it can be added to the already existing standard control structures such as the normal feedback structure or the cascade one without modifying any part of them. Experimental results show that the technique allows the significant reduction of multiple sinusoidal disturbances affecting the same part of the plant.