Community Research and Development Information Service - CORDIS

Self-commissioning speed and position control for electrical drives with identification of mechanical load (SC-DRIVES)

In Europe, especially in Germany and Italy, a large number of machines are produced yielding a high percentage of the worlds production in textile, packaging, paper and plastic extrusion machines. Many of these machines are equipped with controlled electrical servo drives. Due to increasing requirements on productivity and thus on machine utilization, the dynamic performance and accuracy requirements are constantly enhanced. At the same time a high degree of machine flexibility is required to be able to customize the production process without building a completely new machine. An important demand upon modern drives is therefore a quick and highly automized adaptability of the speed and position controllers to various mechanical plants.
Most industrial servo drive applications include mechanical elements like e.g. shafts, gears or belts, which gear up or down torque or speed of the motor and connect elements for mechanical power transmission or for transformation of rotational into translatory motion. These elements show non-ideal transfer characteristics making high precision speed and position control of the mechanical load difficult. Especially elastic transfer elements often result in weakly damped oscillations, which effect the motor shaft and reduce stability of the drive control. Furthermore non-linear effects like friction torque ripple and backlash may cause limit cycles, e.g. stick-slip effects. In most cases the load side motion trajectory shall be optimised while measurement of position and torque is only possible on the motor side. Therefore knowledge of a suitable mathematical model for the mechanic and the according physical parameters is inevitable for optimisation of advanced speed and position controllers.
To enforce the industrial application of advanced control methods making use of a detailed mathematical model of the mechanic and being able to partly compensate the mechanical imperfections, a convenient software tool has been developed by the participating RTDs, which serves for identification, controller selection, controller design and documentation of commissioning results. The tool offers both, a high degree of automation as well as the opportunity for an experienced operator to optimise the controller design interactively. An easy to use man-machine interface supports the operator to perform the experiments and data processing for the identification task and offers a knowledge based controller design and test of the controllers in the field. For the latter a hardware interface has been developed by the SME partners allowing high speed realtime communication between industrial servo drive controllers performing the torque control and a rapid prototyping DSP board which serves as computing platform for the speed and position control. This computer aided commissioning tool has been extensively tested and improved on a mechanical testbed produced by the SME partners for tests at the RTDs and SMEs laboratories. The laboratory tests have been supplemented by field tests on industrial plants.
The main benefit of the project is the availability of a widely applicable tool for the analysis of unknown mechanical systems and for the prototype-like realisation of nearly any control structure. By conduction of field tests the SMEs are able to gain detailed quantitative information about the mechanical plants of their customers wherefore promising control concepts can be derived to be integrated into innovative industrial control devices of the SMEs.

Reported by

University of Paderborn
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