The attitude determination and control system (ADCS) for spacecraft is responsible for determining its orientation using sensor measurements and then applying actuation forces to change the orientation. This chapter details the different components required for a complete attitude determination and control system for satellites moving in elliptical orbits. Specifically, the chapter details the orbital mechanics; perturbations; controller design; actuation methods such as thrusters, reaction wheels, and magnetic torquers; actuation modulation methods such as bang-bang, pulse-width modulation, and pulse-width pulse-frequency; as well as attitude determination using vector measurements combined with mathematical models. In sum, the work describes in a tutorial manner how to put everything together to enable the design of a complete satellite simulator.

This paper explores different reel‐out strategies in a simulated environment to improve the power generation capability of Kitemill's KM1 prototype. The KM1 is a rigid‐wing groundgen airborne wind energy system that flies in circular loops during its power production phase. Firstly, we investigate the impact of flight and ground winch control. A major improvement of 47% more power over an existing reel‐out method can be achieved by combining winch control to maintain a constant reel‐out speed, along with using flight control to track a constant angle of attack and zero sideslip. Subsequently, a series of parameter sweeps were conducted to determine the best reel‐out trajectories. The parameter space considered includes wind speed, circle radius and reel‐out speed. Whilst there are many parameter combinations that provide similar power outputs, their effects on other operation metrics are different. For instance, excessively large circles cause a small drop in power generated (relative to the optimal value) and impose significant penalties on structural load, power quality (how much it fluctuates), airspace and ground space usage and flight control. Regarding the reel‐out speed, faster reel‐out provides more power and alleviates structural load at the cost of lower airspeed relative to the wind, which increases the risk of stalling the airframe. The proposed reel‐out strategies are compared with a published optimisation‐based study, which uncovered the importance of pitch control in power production. All analyses were conducted on a high‐fidelity simulator with tether dynamics. The simulator's accuracy was verified against past flight test data.

In time-marching simulation of airborne wind energy systems (AWESs), the tether is usually discretised into a series of lumped masses (i.e., nodes) connected by spring and damper elements. There is no consensus on the appropriate number of nodes for AWES applications, although it is known that using more nodes than necessary is computationally costly. In this work, we examine the trim solutions of a fixed-wing aircraft connected to the ground by a 500 m tether. A successive difference metric is proposed to quantify the convergence rate of the trim solutions as more nodes are added. We then compare this gain in accuracy to the simulation time and memory usage by plotting their Pareto fronts. Results reveal that using 6–8 tether nodes (i.e., 7–9 segments) is sufficient. Compared to using 15 nodes, 8 nodes keep the successive difference metric below 2%, run over 13 times faster, and require less than a quarter of memories. Beyond 8 nodes, the differential equation solver appears to enter a new stiffness regime, resulting in rapid rises in computation time and memory usage. These findings suggest that the conservative choices of 10–20 nodes can be relaxed, promising significantly lower computation costs in future studies.

This paper presents preliminary results on how to perform waypoint tracking with spacecraft with actuator constraints. It considers a simplified spacecraft model and can be considered a deep space model, and shows how to perform waypoint tracking with only one main thruster together with full attitude control. As the spacecraft reaches close to the waypoint during a deceleration phase that makes the speed go towards zero, reaction control thrusters are used to make the remaining velocity error go to zero achieving the control objective.