An Event-Triggered Robust Attitude Control of Flexible Spacecraft With Modified Rodrigues Parameters Under Limited Communication

Abstract

The attitude regulation of spacecraft using continuous time execution of the control law is not always affordable for the low-cost satellites with limited wireless resources. Of late, within the ambit of control of systems over networks, event-triggered control has proved to be instrumental in ensuring acceptable closed-loop performance while respecting bandwidth constraints of the underlying network. Aligned with these design objectives, a robust event-triggered attitude control algorithm is proposed to regulate the orientation of a flexible spacecraft subjected to parametric uncertainties, external disturbances, and vibrations due to flexible appendages. The control law is developed using a state-dependent single feedback vector, which further assists in obeying the constrained network. The current information of this vector is updated to the onboard controller only when the predefined triggering condition is satisfied. Thus, the control input is updated through communication channel only when there is a need, which ultimately helps in saving the communication resources. The system trajectories, under the proposed approach, are guaranteed to be uniformly ultimately bounded (UUB) in a small neighborhood of origin by using a high gain. Moreover, the practical applicability of the proposed scheme is also proved by showing the Zeno free behavior in the proposed control, i.e., it avoids the accumulation of the triggering sequence. The numerical simulations results are indeed encouraging and illustrate the effectiveness of the designed controller. Moreover, the numerical comparative analysis shows that the proposed approach performs better than periodically sampled data technique and sliding mode-based event-triggered technique.INDEX TERMS Flexible spacecraft, attitude regulation control, limited data transmission, communication constraints, event-trigger, robust control, Zeno behavior, modified Rodrigues parameters (MRP).

Event-Triggered Output Feedback Control for MEMS Gyroscope With Prescribed Performance

“…To effectively compensate for the measurement error and estimation error of LESO, the design parameterm i in control law (22)…”

“…Theorem 1: Consider the MEMS gyroscope model (1), the control signal (22), the LESO (10) and STD (17). For any bounded initial conditions satisfying −λ i ρ i (0) < e pi (0) < λ i ρ i (0), i = 1, 2 there exist constants κ i ∈ R, i = 1, 2, 3 defined by (24), such that all involved signals in MEMS gyroscope dynamics converge to small residual sets, and preselected performance functions ρ i (t), i = 1, 2 are not violated.…”

“…Furthermore, recalling Lemma1 and based on (32), we can conclude that the transient behavior of e pi can be restrained within the predetermined envelopes. Subsequently, recollect the control law (22), it can be easily obtained that the time differentiation of ν i is determined by the signals x vi andx ei . Based on the results of (32), which reveals that all these signals are UUB, we can further derive that there exists a constant ξ i > 0 satisfyingν i ≤ ξ i .…”

“…In [21], fixed threshold triggering mechanisms are blended in the controller design for motor system with nonlinearity, where the existence of Zeno behavior can be avoided. An eventtriggered robust control method is reported in [22] for flexible spacecraft considering limited communication bandwidth. To further reduce the system resource cost, in [23], an eventtriggered and self-triggered H ∞ control algorithm is investigated for a class of uncertain switched linear system with exogenous disturbances, and similar studies can be found in [24] and [25].…”

A fault-tolerant attitude tracking control of spacecraft using an anti-unwinding robust nonlinear disturbance observer

“…Any positive definite matrix scriptJ and a vector ξ=[ξ1ξ2ξ3] T satisfies the following condition 32 where λmin(scriptJ) and λmax(scriptJ) are the positive minimum and maximum eigen value of scriptJ.…”