P$1\mathrm{.}20$ A high$-$performance race car with an adjustable wing $($airfoil$)$ is shown in Figure P$1\mathrm{.}20.$ P$1\mathrm{.}23$ Engineers at the Science University of Tokyo are developing a robot with a humanlike face $[52].$ The robot can display facial expressions, so that it can work cooperatively with human workers. Sketch a block diagram for a facial expression control system of your own design.