What is a true hardware in the loop simulator and what is the difference between a quasi hardware in the loop simulator and a true hardware in the loop simulator?
A true hardware in the loop simulator is similar to the quasi hardware in the loop simulator in that the autopilot software runs on the autopilot hardware and the simulator runs on a separate PC. They differ in the way the sensor values and the control surface deflections are communicated between the autopilot and the simulator. In the true hardware in the loop simulator, the autopilot has the sensors removed and the simulator generates sensor values using digital to analog converters connected to the autopilot. The control surface positions are read by the simulator directly from the autopilot output using a pulse width modulator (PWM) interface board in the PC (most servos for small UAVs are controlled using PWM signals). The advantage of the true hardware in the loop simulator is that it offers the best fidelity of simulation available. There are no delays introduced by transmitting sensor values. Since the simulator generates the actual sensor signals, the autopilot software is ide
