The Wave Ball working principle

Printer-friendly versionPDF version

Despite its simple appearance, the Wave Ball is a state of the art machine with several sensors combined to a powerful software/hardware which allow the Wave Ball to produce and increase the waves with a full control on the frequency and the amplitude.

Wave creation principle

Basis

The Wave Ball is the application result of three physical working principles :

• Archimedes principle: the Wave Ball is a floating sphere placed in the tank working with the principle of the action/reaction.

• Inertia principle: a heavy plate (moving load) is moving up and down inside the Wave Ball shell. As the Wave Ball is placed in the water, the shell is moving up and down around the heavy plate which is not moving thanks to inertia principle.

• Resonance principle: as the Wave Ball is working with several resonance frequencies, the energy given to the pool is kept in the pool thanks to the freeboards. Each time the Wave Ball transmits its energy to the pool, the waves are becoming bigger and bigger until the amplitude of waves requested.

 

Each wave is characterized thanks to several parameters such as amplitude (or height), wave length (peak to peak length) and frequency.

 

 
Amplitude (or height), wave length (peak to peak length) and frequency.
 Pic 1 and fig 1: Characteristics of waves.
 

 

Wave Creation and control

Thanks to the upwards thrust created by the Wave Ball, a first wave is spread in the tank (figure 2). Once reflected against the walls of the pool (figure 3), the wave comes back to the Wave Ball where it will be amplified (figure 4). A computer system computes the right impulsion time in order to increase (or decrease) the waves.

 

 
Some small waves are created by the Wave Ball
Fig 2 : Some small waves are created by the Wave Ball.
 
 
The small waves are spread to the walls of the pool
Fig 3 : The small waves are spread to the walls of the tank.
 
 
The waves are reflected and amplified each time they come back to the ball.
Fig 4 : The waves are reflected and amplified each time they come back to the ball.
 

 

Thanks to its electronic devices, the Wave Ball is able to compute the exact moment when the wave will be back from the walls and to predict when a pulse has to be given. The wave motion is then reinforced at each time a wave comes back to the Wave Ball. The amplitude will then grow until it reachs the requested one (fig 4).

 
Fig 5: Wave Ball behavior
Fig 5: The Wave Ball behavior
 
 

The principle is the same as when you play on the swing and if someone is pushing you. If the person pushes you at the right moment, the amplitude of the movement will increase, even if the force with which he is pushing is weak. At the opposite, if he does not push at the right moment, if he is a little bit off the phase, the movement will stop growing and then decrease.

 

The wave amplitude control

The more the Wave Ball transmits its energy to the water, the more the height of the wave increases. So, if we want to control the amplitude of the waves, we have to control the energy that is transferred from the Wave Ball to the water.

 

The transfer of energy is possible only if the movement of the Wave Ball is shifted from the movement of the wave. To be efficient, the Wave Ball has to anticipate its movement against the one of the wave. The shift between the Wave Ball movement and the wave movement is called the phase difference (figure 11). It is measured in degrees (°). The Wave Ball can give more or less energy by adapting the phase difference between its movement and the wave.

 
Figure 6: Wave mechanism
Figure 6: Wave mechanism.
 

The stationary waves amplitude control

As the waves motion is regular, the Wave Ball can determine with accuracy the amplitude of the waves and the phase difference between its own motion and the one of the wave. The Wave Ball can then adapt this phase difference in order to reduce the amplitude difference between the one measured and the one requested and thus keep the waves at a determinated amplitude.

The non stationary waves amplitude control

As the waves motion is not regular, the amplitude and the phase difference varies rapidly. Thus, it is not possible to control with accuracy the amplitude of the waves. The control enables to get an average of stronger or smaller waves.

 

The Wave Ball and electrical equipment description

The system can be divided into two fundamental units which are the floating Wave Ball in the tank and the control & electrical equipment of the Wave Ball in the technical room.

 

The Wave Ball composition

 

Figure 7: Wave Ball composition

Figure 7: Wave Ball composition.

 
  1. The moving load :  the vertical movements of this load puts the Wave Ball in action. This load is moved by a rod-crank system connected to motor-reduction gear.
  2. The motor-reduction unit : used to put the moving load in motion. The motor is an asynchronous 12V AC motor.
  3. Synchronization sensors : One principal sensor and one backup sensor, used for motor regulation purpose.
  4. Water sensor : used for the detection of water in the Wave Ball
  5. CB50 box : used for sensor acquisition (water and synchronization sensors) and transmission to the electrical cabinet (modulation/demodulation signal) . Contains  the accelerometer for wave frequency and amplitude control purpose.
  6. Umbilical cable : the electrical power needed is supplied by a cable coming from the electrical equipment.

Technical working principle

 

Figure 8: Wave Ball hardware architecture

Figure 8: The Wave Ball hardware architecture
 

 

 

 

The working orders travel on the CAN bus. The CAN bus is a 4 wires bus (2 wires for 12 VDC power supply, 2 wires for data transfer).  The CAN bus has been chosen for its high reliability in the electro magnetically perturbed areas (like in cars), the long cable distance allowed (maximum 500 m with 125 Kb flow rate) and its software controls.

A monophase safety transformer provides the power supply. This transformer is the same for all the range of Wave Balls.

The frequency converter is driven by the CAN card and supplies the 3 phases to the power safety transformer.  The size of inverter and power transformer depends on the Wave Ball size.

The data to communicate between the Wave Ball and the electrical box are modulated on 2 of the 3 Wave Ball power phases cables.

The CAN card

Each device has its own CAN card, which is a multi-interface between the CAN and the other communication channels.

  1. CAN card for the inverter (RS-485)
  2. CAN card for the RCU (TTL)
  3. CAN card for the PowerData card (TTL)
  4. CAN card for the MIO card (TTL)
  5. CAN card for the PC (RS-232)

The use of several CAN cards allows the devices to communicate each other throughout the CAN bus.

The PowerData card

The PowerData is a modem (modulator-demodulator) card, which is used in pair: the first one placed in the Wave Ball (in the CB50 box), the second one in the electrical cabinet close to the transformer (in the PowerData box).

The PowerData card is supplied either from the CAN card (transformer side) or from the CB50 card (Wave Ball side).

The MIO card

The MIO (Module Input Output) is an interface with an external control – command device.  It has 16 configurable inputs/outputs.

Inputs can be used, among other things, to start the Wave Ball from an external device (push button, PLC, ...). The outputs can be used, among other things, to indicate the Wave Ball status to an external device (Light, PLC, ...).

See CB50 software manual for available functions.

The RCU card

The RCU (Remote Control Unit) card contains the human interface functions (keyboard inputs, display) and the memory.  There are two memory zones: EEPROM and RAM.  The active data are in the RAM, the data to save are in the EEPROM.

The RCU card is multi-language (English and French are available).

The CB50 card

The CB50 makes the acquisition of the data coming from the Wave Ball sensors :

  • Accelerometers : measure the wave amplitude;
  • Main zero : measures the Wave Ball frequency (crank rotation speed);
  • Backup zero : verifies the rotation direction;
  • Shell water sensor : detects the abnormal presence of water in the shell bottom;
  • Lock water sensor : detects the abnormal presence of water in the shell lock (for removable cable, only available on W105F(L), W130F(L) and W150F(L) shell);

These sensors information are sent to the bus CAN via the powerdata card.

Components

All cards described above are protected in a box and, depending of the function, combined with another card.

 

Figure 9: RCU box
Figure 9: RCU box

This box called RCU for Remote Control Unit is used to command the wave generator (human interface). The user is able to select different kind of waves, to start and stop the Wave Ball.

 

The RCU box is composed by a display, the wave buttons, the emergency stop, the safety key and the navigation keys.

This box includes a RCU card and a CAN card. The wave regulation (control) is taken in order by the RCU card. The actions to the Wave Ball are given to the inverter throughout the CAN bus.

Figure 10: CAN box
Figure 10: CAN box

This box includes a CAN card configured in RS485 mode. It is the communication device between the CAN bus and the frequency converter.

Figure 11: Power Data box
Figure 11: Power Data box

This box includes a CAN card and a PowerData card. It is the communication device between the CAN bus and the Wave Ball.

Figure 12: MIO box
Figure 12: MIO box

This box includes a CAN card and a MIO card. It is the communication device between CAN bus and an external control command device.

 

This box is associated with a terminal which allows the connection with external devices.

Figure 13: frequency converter
Figure 13: frequency converter

This unit supplies the power to the motor via the transformer and control its speed by changing the electrical frequency (0 ~ 60 Hz). It is driven by the RCU via the CAN bus.

Figure 14: transformator
Figure 14: transformator

The 3 phases transformer converts the output voltage of the frequency converter to the allowed safety output voltage in the pool (12V AC).

 

Two of the three power phases are used for data transfer.

Figure 15: CB50 box
Figure 15: CB50 box

This box includes a CB50 card and a powerdata card.

 

The sensors data are sent to the electrical cabinet thanks to this box.