在Modelica中建模一个简单的嵌入式系统

Question

我想在一个更符合逻辑(或基于行为)的观点而不是低级(电子)观点中,在Modelica(OpenModelica)中建模一个非常简单的嵌入式系统.对我来说主要的问题是,我之前从未与Modelica合作过,而且我在理解如何正确思考如何正确建模时遇到了麻烦.

该系统应该非常简单地用于启动,并且包括通过总线与控制器连接的传感器.系统的期望行为应该是,传感器周期性地生成值并通过中断通知控制器.作为回报的控制器应该对该中断作出反应并获取该值.对我来说,这个例子的目的是,正如我已经提到的,首先要理解如何在Modelica中查看思考并获得一个初始(可能不是非常有用)的工作示例,我可以迭代地扩展到更复杂的一个.

这是我到目前为止建模的系统:

传感器型号:

model ES_Sensor
    parameter Integer id = 1;
    parameter Real frequency = 1.0;
    Integer reg_temperature = 0;
    ES_Interface interface;
algorithm
    when sample(0, 1 / frequency) then
        reg_temperature := reg_temperature + 1;
        interface.interrupt := 1;
    end when;
    when interface.address == id then
        interface.data := reg_temperature;
    end when;
end ES_Sensor;

接口连接器:

connector ES_Interface
    flow Real dummy1;
    flow Real dummy2;
    flow Real dummy3;
    Integer address = 0;
    Integer data = 0;
    Integer interrupt = 0;
end ES_Interface;

总线型号:

model ES_Bus
    ES_Interface master;
    ES_Interface slave;
equation
    master.data = slave.data;
    master.address = slave.address;
    master.interrupt = slave.interrupt;
end ES_Bus;

控制器型号:

 model ES_Controller
     ES_Interface interface1;
     Integer reg_a = 0;
 algorithm
     when
          interface1.interrupt == 1 then
          interface1.interrupt := 0;
          interface1.address := 1;
          reg_a := interface1.data;
          interface1.address := 0;
     end when
 end ES_Controller;

系统型号:

 model Simple_System
     ES_Sensor Sensor;
     ES_Bus Bus;
 equation
     connect(Controller.interface1, Bus.master);
     connect(Bus.slave, Sensor.interface);
 end Simple_System;

如果我尝试模拟"Simple_System",我基本上会得到两个错误.一个告诉我系统是过度指定的(35个方程对26个变量),另一个说:"找到没有时间相关变量的方程式:Controller.interface1.interrupt = 0.0".

我理解的第一个,但我现在绝对想到如何解决它.第二个我根本不明白.

任何帮助,将不胜感激!如果有人至少可以向我推荐一些有用的文献,我也会感激不尽.

Answer 1

好吧,我建议你多读一些关于Modelica的内容.

您可以阅读规范:https: //modelica.org/documents

或者阅读Michael T的免费书籍:http: //book.xogeny.com/

或者从Peter F那里得到一些书:http://www.amazon.com/s？ ie = UTF8&page = 1&rh = n% 3A283155%2Cp_27%3APeter% 20Fritzson

由于您具有非物理连接器,因此应从连接器中删除流变量.此外,在方程式时使用reinit.

connector ES_Interface
    Integer address;
    Integer data;
    Integer interrupt;
end ES_Interface;

model ES_Sensor
    parameter Integer id = 1;
    parameter Real frequency = 1.0;
    Integer reg_temperature = 0;
    ES_Interface interface;
algorithm
    when sample(0, 1 / frequency) then
        reinit(reg_temperature, reg_temperature + 1);
        reinit(interface.interrupt, 1);
    end when;
    when interface.address == id then
        reinit(interface.data, reg_temperature);
    end when;
end ES_Sensor;

model ES_Bus
    ES_Interface master;
    ES_Interface slave;
equation
    master.data = slave.data;
    master.address = slave.address;
    master.interrupt = slave.interrupt;
end ES_Bus;

model ES_Controller
     ES_Interface interface1;
     Integer reg_a = 0;
 algorithm
     when interface1.interrupt == 1 then
          reinit(interface1.interrupt, 0);
          reinit(interface1.address, 1);
          reinit(reg_a, interface1.data);
     end when;
end ES_Controller;

model Simple_System
     ES_Sensor Sensor;
     ES_Bus Bus;
     ES_Controller Controller;
equation
     connect(Controller.interface1, Bus.master);
     connect(Bus.slave, Sensor.interface);
end Simple_System;

现在,如果您实例化模型,您将得到:

class Simple_System
  parameter Integer Sensor.id = 1;
  parameter Real Sensor.frequency = 1.0;
  Integer Sensor.reg_temperature = 0;
  Integer Sensor.interface.address;
  Integer Sensor.interface.data;
  Integer Sensor.interface.interrupt;
  Integer Bus.master.address;
  Integer Bus.master.data;
  Integer Bus.master.interrupt;
  Integer Bus.slave.address;
  Integer Bus.slave.data;
  Integer Bus.slave.interrupt;
  Integer Controller.interface1.address;
  Integer Controller.interface1.data;
  Integer Controller.interface1.interrupt;
  Integer Controller.reg_a = 0;
equation
  Bus.master.data = Bus.slave.data;
  Bus.master.address = Bus.slave.address;
  Bus.master.interrupt = Bus.slave.interrupt;
  Bus.master.address = Controller.interface1.address;
  Bus.master.data = Controller.interface1.data;
  Bus.master.interrupt = Controller.interface1.interrupt;
  Bus.slave.address = Sensor.interface.address;
  Bus.slave.data = Sensor.interface.data;
  Bus.slave.interrupt = Sensor.interface.interrupt;
algorithm
  when sample(0.0, 1.0 / Sensor.frequency) then
    reinit(/*Real*/(Sensor.reg_temperature), /*Real*/(1 + Sensor.reg_temperature));
    reinit(/*Real*/(Sensor.interface.interrupt), 1.0);
  end when;
  when Sensor.interface.address == Sensor.id then
    reinit(/*Real*/(Sensor.interface.data), /*Real*/(Sensor.reg_temperature));
  end when;
algorithm
  when Controller.interface1.interrupt == 1 then
    reinit(/*Real*/(Controller.interface1.interrupt), 0.0);
    reinit(/*Real*/(Controller.interface1.address), 1.0);
    reinit(/*Real*/(Controller.reg_a), /*Real*/(Controller.interface1.data));
  end when;
end Simple_System;

其中有11个方程和14个变量.您将需要更多方程来模拟某些变量的行为.请注意,当方程仅在某个时间点处于活动状态时,它们不会计为方程式.这就是为什么你需要在模型中添加更多的方程式来说明变量如何在时间上连续变化.