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Aerial Cranes
Published in Jie Huang, Nonlinear Dynamics and Vibration Control of Flexible Systems, 2023
Prior literatures have reported the oscillation suppression of quadcopters slung objects. To reduce the oscillations, many examples show that feedback control systems are effective by using measurement and estimation of the suspended-load oscillations [30–38]. However, accurately sensing the suspended load is difficult, and the feedback controller might conflict with the operator's action. Open-loop control techniques have been used to decrease oscillations by modifying commands of the operator to produce a low-swing motion, such as optimal trajectory planning [39–48], flatness-based control [49], and input shaper [50]. In practice, the open-loop controller can reduce oscillations from operator-commanded motions, but cannot control oscillations from external disturbances. Meanwhile, significant efforts have concentrated on modeling and dynamics of the quadcopters slung loads [51–55]. However, all abovementioned works focus on the single-hoist dynamics, which is suitable for small-size loads.
Fundamentals of Control Systems Engineering
Published in Anna M. Doro-on, Handbook of Systems Engineering and Risk Management in Control Systems, Communication, Space Technology, Missile, Security and Defense Operations, 2023
To prevent canceling of unstable roots, A, H, and B must contain only zeros. High-performance (H ≈ 1) open-loop control implements the inverse of the process characteristics A/B to a set point transformation. Considering a dominant-lag process has low gain at large frequencies, its controller has large gain there. A rapid set-point change is reasonably to saturate the manipulated variable, therefore permits its trajectory unchanged. The early return of this variable from its limit creates slower than maximum controlled variable response. This can be avoided by using nonlinear optimization such as quadratic programming suggested by the American Institute of Chemical Engineers (1991) to compute the optimal controller-output trajectory, taking into account output limits, load level, and other process equality and inequality constraints. Further, the performance of an open-loop controller may be negatively affected by an unmeasured load or by discrepancy between and process and the inverse controller at low frequencies. Hence, discrepancy at high frequency will not generate critical difficulty.
Electrohydraulic Systems Control
Published in Qin Zhang, Basics of Hydraulic Systems, 2019
Electrohydraulic systems are commonly controlled using either open-loop or closed-loop controllers. An open-loop controller is completely controlled by the input; the output has no responsive effect on the control action. As shown in Figure 9.2(a), the operation of an open-loop control system is very simple: when the controller receives a control input, it creates a control action, independent of the system variables, to drive the actuator producing an expected output. More precisely, the open-loop system uses no responsive feedback to correct the control action, even though sensors may be used to measure the actual output in some of the systems, and it assumes that a desired control output will always be achieved. Open-loop controls could be a better choice when (1) low cost is a priority; (2) output is simply either on or off; (3) output can be easily predictable; and/or (4) output is fairly consistent. Many mobile electrohydraulic motion control systems often use open-loop control as output is usually predictable and the changes in output in those systems are often very small.
Optimal robust state-feedback control of nonlinear systems: minimal time to target
Published in International Journal of Control, 2021
An example provided in Section 6 demonstrates the superiority of optimal feedback controllers. In this example, an optimal closed-loop controller achieves a significantly shorter time-to-target than an optimal open-loop controller. In addition, the outcome of optimal closed-loop control is less sensitive to uncertainties and errors present in the controlled system's model, thus providing more robust performance than the performance achieved by an optimal open-loop controller.
Stabilisation and set stabilisation of periodic switched Boolean control networks
Published in International Journal of Control, 2023
Jianjun Wang, Renato De Leone, Shihua Fu, Jianwei Xia, Lishan Qiao
In this section, we detect whether the SBCNs with periodic switching signal can be stabilised by open loop controller and state feedback controller respectively, and present the constructive procedure of open loop controller as well as the design algorithms of switching-signal-dependent state feedback controller via Ledley antecedence solution technique.
Vehicle drifting dynamics: discovery of new equilibria
Published in Vehicle System Dynamics, 2021
Sina Milani, Hormoz Marzbani, Reza N. Jazar
Similar to the primary drifting, an open-loop controller is used to destabilise the vehicle and then switches to feedback control afterwards. The inputs and the simulation results are shown in Figures 19 and 20. The path of motion and pose of the vehicle during the manoeuvre is depicted in Figure 21.