@@ -9,7 +9,7 @@ One way to interpret this laboratory/toy gadget is this that it represents an an
## Control systems challenge
From a control systems perspective, this sort-of-kind-of Chinook helicopter has two independent actuators – propellers driven by DC motors. Thrust induced by the two propellers together with the [pitch](https://en.wikipedia.org/wiki/Aircraft_principal_axes#Transverse_axis_(pitch) angle (the angle of the Chinook around the transverse axis motion, determine both the vertical and the forward motion. Since the helicopter is suspended by a long arm anchored at a 2-DOF joint, the former motion exhibits itself as an **elevation angle** of the arm, while the latter exhibits itself as a **travel angle** (angle around a vertical axis) of the same arm. Designing a feedback controller that tracks reference values of both elevation and travel angles by setting the voltages applied to the two DC motors and measuring the three angles (pitch, elevation, travel) using incremental encoders constitutes the control challenge with this laboratory gadget.
From a control systems perspective, this sort-of-kind-of Chinook helicopter has two independent actuators – propellers driven by DC motors. Thrust induced by the two propellers together with the [pitch](https://en.wikipedia.org/wiki/Aircraft_principal_axes#Transverse_axis_(pitch)) angle (the angle of the Chinook around the transverse axis motion, determine both the vertical and the forward motion. Since the helicopter is suspended by a long arm anchored at a 2-DOF joint, the former motion exhibits itself as an **elevation angle** of the arm, while the latter exhibits itself as a **travel angle** (angle around a vertical axis) of the same arm. Designing a feedback controller that tracks reference values of both elevation and travel angles by setting the voltages applied to the two DC motors and measuring the three angles (pitch, elevation, travel) using incremental encoders constitutes the control challenge with this laboratory gadget.
