I understand that you are trying to implement a triggered logic system in MATLAB where “y” should remain unchanged when “x” is within a specific range and invert only when “x” reaches “x_min” or “x_max”.
Your current approach using the “Interval Test Block” causes rapid toggling due to repeated integration steps inside the “epsilon” threshold. To resolve this issue, I suggest two solutions:
Solution 1: MATLAB “Function Block” Approach
You can use a MATLAB “Function Block” with a persistent variable to ensure “y” toggles only when “x” reaches “x_min” or “x_max”. Kindly refer to the following function:
function y = control_logic(x, y_prev, x_min, x_max)
% Define a persistent variable to store the previous state of y
persistent y_state;
if isempty(y_state)
y_state = y_prev; % Initialize y with the given previous value
end
% Check if x is at the boundaries and invert y
if x <= x_min || x >= x_max
y_state = -y_state;
end
% Output the updated y value
y = y_state;
end
This code retains the previous value of “y” using a persistent variable and toggles “y” only at “x_min” or “x_max”, preventing rapid oscillations.
Solution 2: Stateflow Chart Approach
Alternatively, you can use a “Stateflow Chart” for a more structured approach. Follow these steps:
- Open Simulink and add a “Stateflow Chart”.
- Define three states:
- "Hold" (when “x” is within bounds).
- "Invert_Positive" (when “x = x_max”).
- "Invert_Negative" (when “x = x_min”).
3. Set up transitions:
- If “x = x_max”, switch to "Invert_Positive" and set “y = -y”.
- If “x = x_min”, switch to "Invert_Negative" and set “y = -y”.
- Otherwise, stay in "Hold".
This would prevent rapid toggling by ensuring the inversion occurs only at strict boundary conditions and remains stable during integration.
Kindly refer to the following MATLAB documentations for further references:
- https://www.mathworks.com/help/simulink/ug/what-is-a-matlab-function-block.html
- https://www.mathworks.com/help/stateflow/getting-started.html
Cheers & Happy Coding!
