Mechatronics and what it means for hydraulics

Ray Hanley, one of our members who's actively involved in the International Fluid Power Society's Certification Programs, wrote me recently requesting my input on the subject of mechatronics and what it means for hydraulics.

It seems the International Fluid Power Society is evaluating if and how they should be incorporating mechatronics into their certification programs. And that's fair enough. Mechatronics is a buzz word at the moment and I see a lot of Universities and Vocational Colleges scrambling to teach it.

So what's the low down? Here's one definition:

Mechatronics is the synergistic integration of mechanical engineering with electronics and intelligent computer control in the design and manufacture of products and processes.

So hydraulics (and pneumatics) are only a relatively small component of mechatronics as a whole. But the current and expected growth in the integration of electronics with hydraulics in mechatronic systems means:

1. The requirement for hydraulics specialists with advanced knowledge in the field is increasing.

2. Today's hydraulics professionals must have at least basic knowledge in the areas of closed-loop control, electronics, and computer technology.

3. Specialists in other areas, such as electronics and computer programming, must have enough knowledge in hydraulics to identify problems that require involvement of hydraulics specialists.

4. The proper design and functional success of a mechatronic machine typically requires the effective cooperation of a number of different specialists.

The following story by Dr Marian Tumarkin, with whom I co-authored Advanced Hydraulic Control, effectively illustrates all of the above points:

It was Friday - and our final day of testing a complex mechatronic machine featuring four closed-loop electro-hydraulic control systems. As usual, we were behind schedule. The following Monday the machine had to be dismantled and packed for delivery. Our testing team was comprised of top-class specialists: two mechanical engineers, two electronic engineers, a fluid power engineer, a computer programmer and several experienced hydraulic technicians.

Suddenly, during one mode of operation, we were confronted with a strong high frequency sound. A passionate discussion followed. The mechanical engineers were convinced this was a mechanical vibration, and we should focus on looking for its source. I (the fluid power engineer on the team) argued it was self-oscillation - the result of instability in the closed-loop control system. For their part, the electronics engineers asserted that all main parameters were being monitored, and there was no indication of self-oscillation.

Under a great deal of pressure, our team leader sided with the mechanical engineers. The next 32 hours (nearly all weekend) were spent trying to eliminate the 'mechanical vibration': checking all possible mechanical contacts, reassembling the hinge on the main cylinder, lubricating moving parts, etc. But all our efforts were in vain. Eventually, the team leader agreed with my assessment of the problem. I spent 2 (two!) minutes disabling the D component in the electronic PID controller and, to everyone's astonishment, the problem was solved.

Editors note: If you'd like to understand how and why this solved the problem, read pages 192-202 of Advanced Hydraulic Control.

As the above story illustrates, the successful development of a mechatronic machine requires the effective collaboration of specialists from multiple disciplines - who have at least some knowledge in related fields outside their specialty. These include: hydraulics, pneumatics, electronics and computer technology - including system modelling and simulation.

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