Adaptive Finite-Time 6-DOF Tracking Control for Spacecraft Fly Around With Input Saturation and State Constraints

Fuzzy Adaptive Backstepping Control of Nonlinear Uncertain Systems With Unmeasured States and Input Saturation

“…whereˆi x is the observation states, and the fuzzy system function fitting the compound uncertainties can satisfy: xn is An j then θi j , where A1 j , A2 j ,..., An j are fuzzy variables and θi j is an element of adjustable parameter vector. By using product inference, center-average and singleton fuzzifier, the output of the fuzzy system can be expressed as (17) where fuzzy basis function ξi j satisfies…”

“…The deflection range of the rudder angle is ±20deg, and the magnitude of the harmonic interference torque on the pitch axis is: 2×106sin(2t). The traditional method (TM) in [17] shows strong robustness when only considering the presence of interference on the pitch axis. In this paper, the uncertainty of aerodynamic parameters is fully considered.…”

“…The comparison shows that TM cannot ensure the stability of HFV under compound uncertainties, the approximation and tracking errors are significantly large, and the response time cannot be collected owing to instability; the percentages in Table 3 further shows that NM greatly improves TM, NM in this study has excellent performance, the optimal approximation errors are significantly small, which make HFV stable estimation as well as a tracking status and output. Table 4 shows the input comparison of the proposed method and method of [17] that do not consider input saturation. NM has a significantly smaller rudder command at different periods of time; while TM requires a larger rudder angle, which is difficult to achieve under restricted input conditions.…”

“…Owing to the physical characteristics of the actuator's mechanical structure, the actuator signal has a saturation constraint problem [16]. One method to solve this issue is to ignore the influence of saturation constraints and directly limit the amplitude of the control signal after it is solved; this method is complicated in ensuring system stability [17]. A more suitable method would be that considers the saturation limitation of the system in the controller design process.…”

Consensus Control for Wheeled Mobile Robots Under Input Saturation Constraint

“…For example, considering second-order multi-agent systems, Zhai [12] gives a discussion on this issue and designed the distributed controller under the input saturation constraint. And an adaptive finite-time control scheme is developed for noncooperative spacecraft fly-around subject to input saturation in [13]. However, to the best of our knowledge, there are few results considering the input saturation constraint for a wheeled mobile robot, whose dynamics is described by a rigid body on Lie group SE (2).…”