Intelligent Motion Control Systems For Offshore And Maritime Applications
27 September 2005 16:11
In the offshore, maritime and dredging sectors it's all about the clever translation of the desired functionalities into concrete motion control solutions. Wave Generators, Heave Compensators and Jacking Systems all provide examples of the effect Bosch Rexroth has had within these sectors. The combination of different disciplines has been a special feature of the remarkable solutions achieved, bringing functionalities within reach which previously we could only dream of.
The adoption of the latest technologies is what sets Bosch Rexroth's approach apart. The solutions they deliver masterfully combine hydraulic, pneumatic, electrical and electronic systems and components. "It's precisely that multidisciplinary approach that lays the foundations for state-of- the-art solutions," says Ad J.G de Brouwer, General Sales Manager Offshore & Dredging. This company is part of the world wide Bosch group, and can be counted among the leading international specialists in the field of motion control applications. The specific focus of the separate Offshore and Dredging business unit is the development of solutions for the (offshore) oil and gas industry and the dredging and maritime sectors.
"The possibilities in the areas of microelectronics, digital data transmission (bus technology, Wireless LAN), advanced sensor techniques and dedicated and embedded software have expanded enormously in recent years," says De Brouwer. "We can now achieve speeds, accuracies and functionalities in the area of motion control which even five years ago would have seemed completely unattainable. Our Heave Compensators and Deck Mating and Removal systems for example can now respond with extreme rapidity to even the most freakish movements of the sea, amply demonstrating the massive effect on our sector of digital techniques in combination with advanced motion components."
Challenges
We asked De Brouwer for some examples of projects undertaken by Systems & Engineering. "You wouldn't believe the diversity of challenges that are thrown our way," he responds. "A tender vessel needs to come alongside another ship in open water, and the position of the gangway between the two must be kept automatically stabilised regardless of the motion of the sea. We developed a structure with six degrees of freedom, consisting of a pair of triangular steel constructions interconnected by six independently controlled linear drives. Control of the six-axis motion used special sensors and a control system developed in-house, for which we also wrote the software. The results are impressive indeed. Crew can walk easily between the two ships even in the heaviest sea conditions. The system was tested by placing a glass of water on the upper triangle, on the open sea. We didn't spill a drop!"
Heave Compensators
Bosch Rexroth's pre-eminence in the offshore sector is due at least in part to their ultra-reliable Heave Compensators. These systems allow lifting operations to be carried out on the open sea, with load manoeuvres tightly controlled, independent of the movements of the sea. "The great challenge with heave compensation is that the cable from which the load is suspended needs to be lengthened and shortened at high speed to compensate for the vertical motions of the sea," explains De Brouwer. "A company engaged in installing a valuable valve on a structure resting on the sea bed isn't going to be best pleased to see it battered to destruction! Heave compensation is intended to cut out that risk.
Jacking and Skidding systems
Another important area where Bosch Rexroth's offshore know-how comes into full effect is in the field of Jacking Systems. "What we are talking about here is the lifting of huge loads like platforms, top decks and even entire ships (by dockside lifting systems)," says De Brouwer. "There's a tendency in such cases not to think any further than hydraulic solutions, but that is short-sighted. You can also design a fantastic system around electronics, for example using linear drives with rack and pinion systems. The benefit here is that the rack can be of almost any length, allowing extremely large linear displacements.
Deck mating & removal
"Currently, the most advanced combination of systems is found in vessels carrying out Deck Mating and Removal with offshore platforms," continues De Brouwer. "This application combines the principles of Jacking Systems and Heave Compensators. With Deck Mating the vessel travels with the top deck, sitting on its supporting hydraulic cylinders, until it is positioned over the pilings already installed on the sea bed. The movements of the sea have as yet no effect on the structure, because of the distance between the piles and the top deck contact points.
For more information on this company:
Bosch Rexroth - Hydraulic, Pneumatic, Electrical and Mechanical Drive Systems
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