Robust finite-time trajectory tracking control for a space manipulator with parametric uncertainties and external disturbances

Abstract

Space manipulator is considered as one of the most promising technologies for future space activities owing to its important role in various on-orbit serving missions. In this study, a robust finite-time tracking control method is proposed for the rapid and accurate trajectory tracking control of an attitude-controlled free-flying space manipulator in the presence of parametric uncertainties and external disturbances. First, a baseline finite-time tracking controller is designed to track the desired position of the space manipulator based on the homogeneous method. Then, a finite-time disturbance observer is designed to accurately estimate the lumped uncertainties. Finally, a robust finite-time tracking controller is developed by integrating the baseline finite-time tracking controller with the finite-time disturbance observer. Rigorous theoretical analysis for the global finite-time stability of the whole closed-loop system is provided. The proposed robust finite-time tracking controller has a relatively simple structure and can guarantee the position and velocity tracking errors converge to zero in finite time even subject to lumped uncertainties. To the best of the authors’ knowledge, there are really limited existing controllers can achieve such excellent performance under the same conditions. Numerical simulations illustrate the effectiveness and superiority of the proposed control method.

Fixed Time Control of Free-Flying Space Robotic Manipulator with Full State Constraints: A Barrier-Lyapunov-Function Term Free Approach

“…where constant 𝛼 ̿ 𝑖 > 0 is the maximum of 𝛼 𝑖 in (20) when |𝑒 𝑖 | ≤ |𝑒 𝑖 (𝑡 0,𝑖 )| holds. It can be derived in (A22) by using (A4).…”

“…Later, many adaptive controllers [9][10][11][12] and robust controllers [13][14][15] were proposed to handle the system uncertainty, disturbance and nonlinearity. Additionally, to improve the transient performance, a number of works showed the interest in achieving a finite converge time of tracking errors, known as Finite Time Control [16][17][18][19][20]. To detail a few, Ref.…”

Robust Trajectory Tracking Control of Space Manipulators in Extended Task Space

“…where 2 F ∈ denotes external force vector (imitating the action of, e.g., a sub-part to be assembled) exerted on the end--effector. It takes the following form (external forces of a Brownian motion type): (24) where X(t) ~ N(0, 1); i = 1, 2; 0,25 . t ∈ ⎡ ⎤ ⎣ ⎦ The actuator matrix B in (1) equals ( ) ( ) whose posture is described by two position variables x 1,c , x 2,c and orientation angle q with respect to the global coordinate system OX 1 X 2 .…”

“…In order to increase the mobility of in-orbit robotic systems, both thrusters of spacecraft and actuators of holonomic manipulator are assumed to be active (in works [11-13, 15, 16, 24]) in controlling the space manipulator during the trajectory tracking tasks. Unfortunately, a vast majority of control algorithms is expressed in the space of generalized (joint) coordinates [11][12][13]24]. Due to the fact that a huge amount of trajectory tracking tasks is expressed in Cartesian (task) coordinates, the algorithms proposed in works [11][12][13]24] are not suitable for accomplishment of such tasks.…”

“…Unfortunately, a vast majority of control algorithms is expressed in the space of generalized (joint) coordinates [11][12][13]24]. Due to the fact that a huge amount of trajectory tracking tasks is expressed in Cartesian (task) coordinates, the algorithms proposed in works [11][12][13]24] are not suitable for accomplishment of such tasks. Only a very few works has been reported which tackle the problem of trajectory tracking control of fully actuated space manipulators in task coordinates.…”