It is useful to set the absolute and relative tolerances to a higher value to avoid this warning. In case of sharp discontinuities in the reference input such as when tracking a reference signal, it is possible that this warning is generated at intermediate time steps. MATLAB is trying to reduce the time step to a really small amount in order to counter the abrupt change due to the discontinuity in the reference signal.
For sharp discontinuities,it might not be possible to avoid this warning. However for non discontinous inputs we can set relative and absolute tolerance to a higher number than the default setting.
We can set the tolerances to a higher value for example by using the following commands:
options = odeset('Mass',M,'RelTol',1e-4,'AbsTol',1e-6);
[t,y] = ode15s(@objectivefunction,tspan,y0,options);
For more information on relative and absolute tolerance you can look at the link below:
