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In order to work on specific control methods for model-free control of switched controllers we used electronic end-position damping of pneumatic cylinders as a first test application. Its aim is to reduce the kinetic energy of the mass which is moved by the pneumatic cylinder before it reaches the end-position in order minimize mechanical shocks and to obtain a minimal time for a move at the same time.

Requirements which had to been met are:

• tolerate 100 % change of load mass
• control design without a formal process model
• adaptation to severe time-variant effects
• off-the-shelf product
• simple tuning for the entire pneumatic set-up
• suited for low cost micro-controllers (16 bit)
• use of standard low cost pneumatic components

Due to cost reasons, ordinary switched valves are used. They introduce severe (and unknown) response times which have to compensated by the control method. This was solved by using self-tuning and adaptation in combination with a model-free approach. The following figure compares the kinetic energy at the end of a move for a typical cylinder moving different load masses with and without electronic end-position damping. It clearly shows the effectiveness of the SEED-approach which got the Smart Adaptive System-Award of EUNITE in 2003.

Results



The following video demonstrates the self-tuning process right from the beginning starting with a SEED-controller just "off-the-shelf", i.e. not tailored to the specific set-up.


The SEED-approach had become a commercial product (´SPEEDyControl´) by Kuhnke GmbH, Malente, Germany.