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Task scheduling & event management using the Statechart Environment of Simcenter Amesim

Dreamer
Dreamer

The industry is evolving and the cooperation of mechanical, electronical and information systems in machines and systems becomes increasingly closer. A new functionality and productivity of machines can only be conceived and implemented with an interaction of the components. Not only does Simcenter Amesim help you bring together mechanical, hydraulic, electrical, pneumatic and thermal components, it also enables you to address challenges related to task scheduling and event management when modeling controllers’ architecture.

To facilitate the creation of statecharts, Simcenter Amesim offers you an intuitive environment to model and simulate complex logic.

Let’s take an example of an electronic control unit of the gasoline injector solenoid.

 

Simcenter_Amesim_model.pngInjector model in Simcenter Amesim

  

Electronic control unit

 

Simcenter_Amesim_control.pngElectronic control unit

The solenoid of the injector is driven by a dedicated electronic control.

It is made of:

  • Two voltage sources: 12V of the battery of the vehicle and 40V from a charged capacitor. The electronic structure charging the capacitor to 40V is not represented here
  • Three transistors T_on_off, T_peak, and T_hold to control the voltage applied to the solenoid
  • Two diodes for current protection and transition mode
  • One statechart to handle dedicated events

 

Statechart

 

Simcenter_Amesim_statechart.pngStatechart

 The statechart is defined by:

  • Two inputs:
    • on_off: on/off command to start and stop the injection cycle
    • current: sensed current in the solenoid
  • Three outputs:
    • dt_inj: T_on_off transistor command
    • dt_peak: T_peak transistor command
    • dt_hold: T_hold transistor command
  • Three parameters:
    • t_peak: peak mode duration
    • Iholdmin: minimum current value in hold mode
    • Iholdmax: maximum current value in hold mode

The solenoid is driven to be closed and then released. During the closing two modes can be distinguished: the peak mode and the hold mode.
During the peak mode, the maximum voltage is applied to the solenoid in order to have the fastest closing.
During the hold mode, the current in the solenoid is controlled in order to be maintained closed with a minimum solenoid current.

 

Analyze

It is then possible to fully characterize the injector by looking at the injected mass flow rate with respect to pressure and pulse duration.

 

Simcenter_Amesim_plot.pngInjected mass flow rate variation

  

To sum up, the Statechart Environment helps you design logic for supervisory control, task scheduling, and fault management applications when modeling systems.

Simcenter Amesim allows you to simulate combinatorial and sequential decision logic based on state machine.

Contributors