This is the same diagram of the 1st prototype. you can see that there is a spring mechanism holding the blades in place. as the rpm of the turbine increases the turbine arms gets pulled outwards due to centrifugal force. as it moves outwards it follows the path cut out on the arm holder(visible in the pic). This twists the blade and change the angle of attack.
The spirit of Research and Developement
Read an article on this innovation here
Picture Credit :: Yumnam Devjit