Switching simulink function based on simulation time

Hello,

I have a 3DOF robot arm that must go through a sequence of 6 different motions. I have a matrix of the relative movement each degree of freedom needs to make and a time vector specifying how long I want each motion to take. These values are being put into a 5th order polynomial to calculate the position profile for each DOF. Each of these motions have different position motion profiles driving them. In short, what is the best way to sequence through the equations based on the simulation time?

For example, from time 0 to T1 I want equation 1 to command the position, from T1 to T2 I want equation 2 to command the position, etc.

Each of the equations give position of the arm relative to where the last equation ended. Currently I have a convoluted system of using step blocks to turn on and turn off the equations as the simulation runs but I know there must be a simpler way.

Any suggestions would be greatly appreciated!

Thanks.