2D Simulation of UAV, no data

I'd like to simulate a simple model of a UAV flying around (lawnmower pattern) covering a total area and plot its path in a Matlab window. It has constant altitude, constant speed and no disturbances for now. So I only care about the x and y coordinates and the yaw angle. I don't have any gyro or accelerometer measurements, it's all software based so I'm wondering how to do this. It should take fixed-wing dynamics into account. So I guess the only thing I'd like to control is the yaw-angle, is this a proper setup?

x(k+1)=x(k)+Ts*v*cos(psi(k)) y(k+1)=y(k)+Ts*v*sin(psi(k)) psi(k+1)=psi(k)+Ts*u;

How do I design the control input u? Let's say I have a desired point I'd like to go to. I know this might be too much of a general question, but please I just need some guidelines.