Reference projects

Our projects usually have long term nature. Except for technical feasibility studies and other studies of short term nature usual project time span extends over a period of 3 to 5 years. Our reference projects include:

This ambitious project targeted to develop and validate a commercially feasible active suspension system for high-rise high-speed elevators capable of active vibrations damping as well as position control of the elevator car relative to the guide rails during travel.

The developed system is composed of 8 linear motors, 6 accelerometers, 8 position sensors, a signal conditioning unit and the relevant power electronics, with the whole system controlled by a real-time computer equipped with the required interfaces.

The following are the different systems engineering tasks that were accomplished through the successful system development:

  • Setting the specifications for the sensors, the actuators and the remaining subsystems, such as the signal conditioning unit, based on the results of the corresponding modeling and simulation runs.
  • Selection of the sensors and cooperation with the producers of the linear motors in order to dimension, construct and test the selected actuators
  • Evaluation and procurement of the real-time computer system, which is used for the system identification and system control.
  • Total system integration and testing.
  • Project management including the planning and budgeting as well as the reporting and presentation to the client.

Parallel to the system engineering the following system dynamic analysis and controller synthesis jobs were accomplished:

  • Development of a Multi-Input Multi-Output (MIMO) system identification procedure in the frequency domain, in order to obtain a linear time invariant system model with 6 input signals and 12 output signals. The model considers all couplings between the degrees of freedom of the system and is used in the controller design.
  • Development of a controller synthesis procedure to be realized in two main steps. In the first step the closed loop employing the feedback of the acceleration measurement is designed in order to actively damp the vibrations. As the asymmetric loading of the cabin will badly influence the orientation of the elevator car relative to the guide rails and one or more actuator may touch their stoppers and hence become disabled, the orientation of the elevator car within the guide rails must be corrected with the help of the a second closed loop employing the feedback of the position measurements. To optimize the performance of both control loops the effectiveness of the acceleration feedback loop is limited to the frequency range in which humans are sensitive to vibrations, which starts at 0.5 Hz. Accordingly, the bandwidth of the position feedback loop will be set to a frequency slightly less than this frequency. The most suitable controller synthesis method for the design of both feedback control loops was found to be the H-infinity MIMO design method.
  • Since the elevator will exist as a system after its installation, the above-described procedure must be able to be conducted on site and needs to be simplified, so that the available commissioning personnel may be trained to accomplish it.

Active Ride Control is currently a commercialized industrial system within the sales program of a major world elevator producer.

For a dedicated presentation on the subject please contact us.