how can I switc between three systems of ODEs basing on the value of the second solution of each system, and repeat the cycle ?

I have three systems of differential equations, each systemt consists of ten equations, and the first system has initial conditions.

I want to automate the solution and switching between these systems where:

When the value of the second solution of the first system reaches a certain value (symbolised by T_b), the solution of the first system stops and the solution of the second system begins, whose initial conditions are the final conditions of the first system.

When the value of the second solution of the second system reaches a value less than T_b, the solution of the second system stops and the solution of the third system starts, whose initial conditions are the final conditions of the second system.

when finish this , repeat the cycle untill finishin the time spane (200 hours).

[Torsten]

Use the "events" facility of the ODE integrators:

https://uk.mathworks.com/help/matlab/math/ode-event-location.html