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563 Wellesley Drive
Birmingham, MI 48009-1518
TEL: 248-646-1811 FAX: 248-646-1855
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CUSTOM ELECTRO HYDRAULIC SERVO-MECHANISMS FOR INDUSTRY
PRODUCTS AND SERVICES
The Nicholson Engineering Company has developed custom electro-hydraulic servomechanisms for many different industries. We work with the client to develop an understanding of the needs and desires of the machine or process, resulting in a fully integrated control, which is just right for the application.
In addition to serving as an engineering consultant, a standard line of servoamplifiers has been created which can, with minor modifications, satisfy most applications. A typical board is illustrated on the next page. We can provide the right amplifier for your servovalve in those situations where the customer is comfortable performing the systems integration.
The Nicholson Engineering Company is fully capable of providing complete control packages or even complete machines. Custom circuitry is developed which interfaces with the various components of the system, creating an integrated whole. Custom software is created to translate the signals from the operator interface into the required machine actions.
BACKGROUND
Bob Nicholson received engineering training at Northeastern University and then at the Massachusetts Institute of Technology where he studied control engineering while earning the SM degree from the department of Mechanical Engineering. He received an MBA from the University of Detroit shortly thereafter. He is licensed as a Professional Engineer by the State of Michigan.
Mr. Nicholson holds many patents on servovalves and related servomechanisms.
Since 1969, he has been gaining experience in the operation of closed loop electro hydraulic servomechanisms. After more than a decade of employment as the engineering manager for a major industrial servo valve manufacturer, the Nicholson Engineering Company was founded in 1982.
Since 1982, many diverse industries have been helped by our services as illustrated by the following list: All three US automotive manufacturers, several electric utilities, fighting vehicle manufacturer, the National Labs at Los Alamos, NM and Auburn, AL, machine tool manufacturers, sawmills, repair facilities, testing machine manufacturers, test labs, motion base manufacturers for both flight simulators and entertainment rides, injection molders, and a servovalve manufacturer.
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APPLICATIONS
Machine Tool:
In 1985, one of the auto manufacturers, in conjunction with a machine tool builder, developed a roller burnishing process that vastly improves the life of the engine crankshaft. The Nicholson Engineering Company developed the fifteen channel ServoController to precisely apply the burnishing pressure to the crankshaft journals in response to discrete and analog signals from a programmable controller. Virtually all the engine plants in North America now use this process.
Utilities:
Some generating stations were having a problem with the 700 hp variable speed condensate pumps. Because the electro-hydraulic speed control had been poorly implemented, it was marginally stable and very susceptible to servovalve degradation. Naturally, these pumps were not a commercial success and the manufacturer abandoned the product, making service and parts unobtainable. Since operation of the generator is dependent on this pump, the problem easily went critical.
Nicholson Engineering Company provided an Atchley Servovalve and some interface electronics to replace the problem valve. Once on site for the installation we simplified the electronics and wrote a straightforward calibration procedure for the system.
The pump control is rock solid now. The difference between the command from the control room and the speed is miniscule, even during transients. What had been a regular maintenance nightmare now is not even serviced during scheduled outages.
Testing Machines:
A midwestern electromagnetic actuator manufacturer needed a test machine which would apply a static load over a 7,000:1 range with very little load variation as the actuator operated at speeds up to a few kHz. A machine was conceived and built which met all the requirements.
The machine is completely automatic. Even the transducer calibration is automatic. Just load the DUT, press the start button and it goes right to the set load.
WHY CLOSED LOOP SERVOS ?
Closed loop servos aren’t for everyone. Some machines do not need it by their simple nature. This technology does offer the ultimate in convenience, accuracy, and reliability.
Properly done, very high restoring forces will result from very small errors and with very stable movements. Multiple controlled positions can be achieved simply from a new setpoint signal to the servo controller. Alternatively, one channel could be made to track another or some other parameter.
Static accuracies need only be limited by the accuracy of the transducer used.
The general arrangement utilized is shown in the above diagram. Any parameter that can be influenced by the servovalve and measured by a transducer can be controlled with this technique.
Closed loop servomechanisms may seem like an overkill in many cases, but the benefits are substantial.
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