Position Control Scheme Research Articles

Fault-tolerant attitude tracking control of combined spacecraft with reaction wheels under prescribed performance

Capture and control of a failed spacecraft can be achieved by a space manipulator installed in a service spacecraft. After this target has been captured, the combined spacecraft must be controlled in a prescribed way. The attitude attacking control of the combined spacecraft system is one major challenge since the mass properties of the whole spacecraft system and configuration matrix of the reaction wheels change, especially when actuator fault occurs. In this paper, a nonlinear disturbance-observer-based fault-tolerant attitude control scheme is developed for the combined spacecraft with prescribed performance. Firstly, an approach is given to reconstruct the attitude tracking dynamics of the combined spacecraft with reaction wheels. Then, a fault-tolerant controller, based on dynamic surface method and nonlinear extended state observer, is developed whereby performance in the light of convergence time, stability and accuracy with inertia uncertainty, actuator saturation and external disturbance can be prescribed. Finally, comparative simulations in both actuator faults and actuator fault-free cases are conducted to show the superiority of the developed attitude tracking control method.

High-Precision Attitude Tracking Control of Space Manipulator System Under Multiple Disturbances

Precise attitude control of space manipulators plays an important role in advanced on-orbit assembly tasks. The vibration of flexible appendage and inertial uncertainties encountered in the operating process, however, may cause attitude error or even safety threats to the space manipulator system. In this article, a high-precision attitude control scheme of a space manipulator system is designed via a combination of disturbance observer (DO), prescribed performance-based H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> control, and iterative learning control (ILC) techniques. The proposed control scheme consists of three portions: 1) a DO that estimates the vibration disturbance caused by flexible appendage of base satellite; 2) a robust H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> controller with prescribed performance to attenuate the inertial uncertainties resulting from capture of an unknown object; and 3) an ILC for improving the transient and steady-state process in the presence of a repetitive on-orbit assembly task. This novel control scheme can not only handle the flexible vibration and inertial uncertainty of the space manipulator but also achieve satisfactory tracking performance. Both simulation and experimental results confirm the superiority of the proposed control strategy.

Fixed-time attitude stabilization for a rigid spacecraft

This paper mainly investigates the problem of the attitude stabilization for a rigid spacecraft based on the model of Modified Rodriguez Parameters. A fixed-time attitude stabilization controller is designed to guarantee that the attitude of the rigid spacecraft will be stabilized to the equilibrium in a fixed time which is independent of any initial condition. The design of fixed-time attitude controller is mainly based on improved backstepping method. The proposed fixed-time attitude control scheme can deal with not only the parameters’ uncertainties but also the external disturbances. Reliability and effectiveness of the proposed approach are proved by simulations.

A pseudospectral method based robust-optimal attitude control strategy for spacecraft

This paper proposes an optimal integral sliding mode control (ISMC) scheme for attitude regulation of the rigid spacecraft. This control technique is capable of handling inertial matrix uncertainties as well as external disturbances. To incorporate optimality into the robust control law, the ISMC is integrated with Legendre pseudospectral method (LPSM). The minimization of the cost function and constraint handling of the spacecraft is obtained by LPSM, while the ISMC provides disturbance rejection. LPSM is chosen for its relatively high rate of convergence and its capability of solving a wide range of challenging optimal control problems. Theoretical stability analysis of closed loop system using Lyapunov theorem guarantees the convergence of attitude states. A comparative analysis between the proposed LPSM-ISMC and Chebyshev Pseudospectral Method (CPSM) based ISMC, is also presented in this paper. The effectiveness of the proposed robust-optimal control strategy is established through simulation results.

Position Control of Parallel Active Link Suspension With Backlash

In this article, a position control scheme for the novel parallel active link suspension (PALS) with backlash is developed to enhance the vehicle ride comfort and road holding. A PALS-retrofitted quarter car test rig is adopted, with the torque flow and backlash effect on the suspension performance is analyzed. An elastic linear equivalent model of the PALS-retrofitted quarter car, which bridges the actuator position and the equivalent force between the sprung and unsprung masses, is proposed and mathematically derived, with both the geometry and backlash nonlinearities compensated. A position control scheme is then synthesized, with an outer loop H $_{\infty}$ control for ride comfort and road holding enhancement and an inner loop cascaded proportional-integral control for the reference position tracking. Experiments with the PALS-retrofitted quarter car test rig are performed over road cases of a harmonic road, a smoothed bump, and frequency swept road excitation. As compared to a conventional torque control scheme, the newly proposed position control maintains the performance enhancement by the PALS, while it notably attenuates the overshoot in the actuator's speed variation, and thereby it benefits the PALS with less power demand and less suspension deflection increment.

Reliability Analysis on Power Converter of Switched Reluctance Machine System Under Different Control Strategies

In this paper, a novel reliability assessment scheme is presented to achieve the optimal selection of control strategies for switched reluctance machine system from the perspective of reliability. To begin with, a combination model of k-out-of-n :G model and Markov model is proposed to lower the complexity and enhance the accuracy of system-level reliability assessment. As for the component-level reliability assessment, the three-dimensional coupled thermal circuit model of power converter is built to achieve the precise and fast prediction of junction temperature that is necessary for calculation of failure rate. Then the static and dynamic reliability analyses are carried out under voltage chopping control (VCC), current chopping control (CCC), and angle position control (APC) strategies, which indicates that the implementation scope of the APC strategy should be broadened. Compared with the VCC strategy, the CCC strategy is strongly recommended even if current sensors boost the extra failure rate. Besides, the increase in redundancy levels on power converter is certified as the most powerful measure for reliability enhancement of the SRM system and the most cost-effective redundancy level can also be quantitatively obtained. The experiments of fault-tolerance capability and thermal stress indirectly verify the validity of reliability analysis.

Single-motor-unit discharge characteristics in lumbar multifidus muscle of acute low back pain patients

Acute low back pain (ALBP) causes rapid deterioration of paraspinal muscle function. The underlying neurophysiology is poorly understood. We therefore carried out this observational study in patients with ALBP to characterize motor unit (MU) activity in deep lumbar multifidus (LM) muscle and compare with our previous findings from pain-free subjects. Nine subjects (1 woman; age 26-59 yr) with ALBP duration of 1-21 days were recruited from outpatient clinics. Fine wire electromyography (EMG) electrodes were implanted bilaterally at the painful spinal level under computer tomography guidance. EMG was recorded during spontaneous sitting and standing, and during voluntary force production. Linear mixed models were utilized to test or control for the effects of a number of predefined variables. Compared with sitting, standing increased total duration of EMG activity, median MU discharge rate, interspike interval variability, and common drive measured as common drive coefficients (CDC) derived from concurrently active MU pairs. Median discharge rate in 73 MUs was 5.5 and 6.6 pulses per second (pps) during spontaneous sitting and standing, and 7.2 pps during voluntary force production. Interspike interval variability was lower during voluntary tasks than during spontaneous force production. Common drive was less pronounced in bilateral vs. unilateral unit pairs, also in spontaneous standing. This difference was not seen in our previous pain-free subjects, suggesting altered bilateral control of the spine in ALBP. The distribution of CDC values was not a homogeneous continuum but could be seen as two partially overlapping populations of CDC distributions.NEW & NOTEWORTHY We implanted fine-wire electrodes in the deepest part of axial postural muscles in patients with acute low back pain and characterized their motor unit activity. We found less pronounced common drive to the two sides of the spine compared with pain-free subjects, suggesting a different postural control strategy in patients with acute low back pain. An unexpected finding was that common drive coefficient values appeared to consist of two partially overlapping populations of normal distributions.

The Amount and Temporal Structure of Center of Pressure Fluctuations During Quiet Standing in Patients With Chronic Low Back Pain.

The characteristics of postural sway were assessed in quiet standing under three different postural task conditions in 14 patients with nonspecific chronic low back pain and 12 healthy subjects using linear and nonlinear center of pressure parameters. The linear parameters consisted of area, the mean total velocity, sway amplitude, the SD of velocity, and the phase plane portrait. The nonlinear parameters included the Lyapunov exponent, sample entropy, and the correlation dimension. The results showed that the amount of postural sway was higher in the patients with low back pain compared with the healthy subjects. Assessing the nonlinear parameters of the center of pressure showed a lower sample entropy and a higher correlation dimension in the patients with low back pain compared with the healthy subjects. The results of this study demonstrate the greater regularity and higher dimensionality of the center of pressure fluctuations in patients with nonspecific chronic low back pain, which suggests that these patients adopt different postural control strategies to maintain an upright stance.

Haste makes waste: on the trade-off between walking speed and target-stepping accuracy

Previous findings suggest that wearing a lumbar belt may benefit some patients with low back pain; however, the mechanisms of action are not yet fully understood.The effect of wearing two flexible (extensible and non-extensible) lumbar belts on trunk postural control was investigated during an unstable sitting task.Healthy subjects and subjects with LBP sat on a wobbling chair, with and without the lumbar belts. Chair rotation was measured in the sagittal and frontal planes, and 10 linear and nonlinear measures of balance were computed to assess the quantity (3 measures) and quality (7 measures) of the movements.Both lumbar belts induced similar changes in specific measures of trunk postural control, for both subject groups, generally indicative of more instability and less controllability, but with low effect sizes (0.14 and 0.40). Subjects with LBP also showed lower entropy (complexity; effect size 0.93) and higher determinism (predictability; effect size 0.56) than healthy controls, under all test conditions. These findings indicate that the subjects with LBP used a less complex, more predictable trunk postural control strategy, suggestive of impaired adaptability and responsiveness to dynamic trunk postural control demands. The findings also suggest other factors related to dynamic adaptability may be impaired by lumbar belt use.The effects of the lumbar belts on trunk postural control were small, however, their practical implications for the management of LBP remain to be determined in relation to other effects of lumbar belts (e.g. increased mechanical stiffness).

Combined velocity and position control of large inertial hydraulic swing mechanism considering energy balance of supply and demand

Abstract The position of a conventional large inertial hydraulic swing system is controlled by the operator-in-loop, the production efficiency of which is poor, and the repetitive positioning precision is low owing to slow human reactions. To address this problem, this study proposes a combined velocity and position control strategy based on the independent metering control system. In this method, it is not necessary to change the conventional operation mode. If the required rotary angle is the same in each swing process, a precise desired position is provided as the input signal for closed-loop position control. If the required rotary angle is random, in order to be compatible with the handle operation mode used in mobile machines, a handle signal integral control method is proposed. Moreover, velocity feedback is used to improve the control accuracy, while differential pressure feedback is used to reduce the position overshoot. Meanwhile, to improve the system dynamic characteristics during the braking process, an energy balance principle is applied. The proposed strategy is verified with simulation and a 6 t hydraulic excavator. The simulation and experimental results demonstrate that a higher positioning accuracy can be achieved with different desired angular displacements. Furthermore, the position overshoot, and velocity and pressure fluctuation are avoided, while the dynamic characteristics are clearly improved.

A New Position and Speed Estimation Scheme for Position Control of PMSM Drives Using Low-Resolution Position Sensors

A new position control method for permanent magnet synchronous motor (PMSM) drive with a low-resolution encoder is proposed in this paper. Three binary Hall position sensors are utilized to realize a moderate-performance position control system for the consideration of economy and simplicity in servo application. Compared with sensorless control, the usage of binary Hall position sensors is a guarantee of both control performance and low cost. However, the low resolution of the Hall sensor will heavily deteriorate the accuracy of the position and speed calculation. Such drawback can be effectively minimized by using appropriate position and speed estimation schemes. With the help of polynomial fitting and state observer techniques, a solution is provided to realize semi-closed loop control by treating the position and speed estimators as separate systems. The performance can be improved (1) by proposing a polynomial fitting scheme with least squares method, high-resolution rotor-position predictor can be derived by fitting the predefined position data from binary Hall position sensors in a linear or quadratic manner; (2) by adopting the dual-sampling-rate observer, instantaneous speed can be estimated at each control cycle and the estimation error is corrected once a new measurement form the Hall arrives. Furthermore, a nonlinear position control algorithm is introduced to increase standstill stability. Extensive experimental results are given to demonstrate the feasibility of the proposed method and its superiority over conventional methods.

Abnormal hypersynchronization of body balance control system in children with post-burn foot deformity

Relevance. Treatment of children with post-burn foot deformities is an important task of reconstructive plastic surgery. The scars formed on the back surface of the feet, even with adequate surgical approach, in the acute period of thermal injury, further often lead to deformities of the entire foot, which leads to a derangement of its support function. The importance of the problem lies in the fact that with the growth of the child, secondary abnormal changes develop on the part of the joints of the lower extremities and the spine, leading to impaired locomotor function, including deviations in the body balance control system.&#x0D; Purpose of the study. To study postural stability in children with post-burn foot deformities before and after surgical treatment.&#x0D; Material and methods. The stabilometric study was conducted in 12 patients with post-burn cicatricial foot deformity, the average age of the patients was 9.8 ± 0.93 years old. The control group consisted of 12 children of the same age with no signs of orthopedic abnormality. To assess the results, the methods of descriptive statistics with the inclusion of correlation and regression analysis were used.&#x0D; Results. In patients with post-burn cicatricial deformity of the foot at the pre-treatment stage, a compensatory redistribution of the static load towards the intact lower limb was revealed. Analysis of postural control indicators in patients of the main group showed an abnormal increase in the synchronization of the system of body balance control. After reconstructive operations on the affected foot, symmetry of the distribution of the load and restoration of the support of the limb of the affected side were noted. Correlation analysis revealed a pronounced decrease in abnormal hypersynchronization between stabilometric parameters, which may indicate a trend towards normalization of the postural control strategy in patients after treatment.&#x0D; Conclusion. Elimination of post-burn foot deformity contributed to the restoration of its anatomical shape and was accompanied by pronounced positive dynamics in the state of the system of vertical balance of the patient’s body.

Altered movement strategy of chronic ankle instability individuals with postural instability classified based on Nyquist and Bode analyses

BackgroundThe aim of the current study was to assess movement strategies during a single leg balance in chronic ankle instability individuals with unstable postural control strategy identified by Nyquist and Bode analyses in conjunction with sample entropy. MethodsThirty-three participants with self-reported chronic ankle instability and 22 healthy controls performed single-leg eyes closed static balance trials. The sagittal and frontal plane kinematics in the lower extremity and trunk as well as center of pressure trajectories were recorded during three, 20-second trials. The Nyquist and Bode stability analyses, which classify center of pressure waveforms as stable based on the resulting gain and phase margins, were performed to identify the presence of postural control deficits. Sample entropy was implemented to analyze movement strategies during the task. FindingsBased on the Nyquist and Bode stability analyses, we included 19 out of 33 chronic ankle instability participants with unstable postural control strategy and 16 out of 22 controls with stable postural control strategy in the final analyses. Chronic ankle instability participants demonstrated a significantly lower sample entropy value in sagittal and frontal plane trunk kinematics and sagittal plane hip kinematics compared to the controls. No between-group differences existed in other kinematic measures. InterpretationThe lower sample entropy values in participants with chronic ankle instability indicates that those with postural control deficits may increase reliance on the trunk and hip joint contributions to the maintenance of postural control, reflecting changes in the sensorimotor constraints on movement patterns during the task.

Age related differences in balance approached by a novel dual-task test of anticipatory postural control strategies.

IntroductionAssessment of balance is key to identifying individuals with postural control deficits and an increased fall risk. Subjects may compensate for their deficits by utilizing other strategies; to avoid this, it is recommended to assess postural control using a dual-task test. In most dual-task tests, it is difficult to monitor the performance in the secondary task and the individual’s task prioritisation. This study evaluated a new dual-task testing approach.Materials and methodsA convenience sample of 54 community-dwelling elderly (age 65+ years) and a reference group of 20 young participants were included in the study. They performed a test in which they could utilize cues to improve their baseline performance, provided their level of postural control allowed them residual attention capacity for this cognitive task.ResultsSignificant performance differences were seen between the young and the elderly. The young group improved their performance time by 23.9% (10.7) and 7.1% (14.2) with a cue and a reverse cue, respectively, whereas the elderly failed to improve their performance time. The test was unable to distinguish between individuals within the elderly group due to a floor effect.DiscussionThe test reveals an individual’s capacity to use cues for anticipatory postural control strategies in a dual-task setting and thereby estimates automatization of postural control. While the young subjects were capable of improving their performance during dual-task conditions, the elderly subjects apparently had no residual attentional capacity allowing them to utilize the facilitating cues. Within the elderly group, the dual-task aspects of the test added no value with respect to differentiation in the level of postural control.

The effect of extensible and non-extensible lumbar belts on trunk postural balance in subjects with low back pain and healthy controls

BackgroundPrevious findings suggest that wearing a lumbar belt may benefit some patients with low back pain; however, the mechanisms of action are not yet fully understood. Research questionThe effect of wearing two flexible (extensible and non-extensible) lumbar belts on trunk postural control was investigated during an unstable sitting task. MethodsHealthy subjects and subjects with LBP sat on a wobbling chair, with and without the lumbar belts. Chair rotation was measured in the sagittal and frontal planes, and 10 linear and nonlinear measures of balance were computed to assess the quantity (3 measures) and quality (7 measures) of the movements. ResultsBoth lumbar belts induced similar changes in specific measures of trunk postural control, for both subject groups, generally indicative of more instability and less controllability, but with low effect sizes (0.14 and 0.40). Subjects with LBP also showed lower entropy (complexity; effect size 0.93) and higher determinism (predictability; effect size 0.56) than healthy controls, under all test conditions. These findings indicate that the subjects with LBP used a less complex, more predictable trunk postural control strategy, suggestive of impaired adaptability and responsiveness to dynamic trunk postural control demands. The findings also suggest other factors related to dynamic adaptability may be impaired by lumbar belt use. SignificanceThe effects of the lumbar belts on trunk postural control were small, however, their practical implications for the management of LBP remain to be determined in relation to other effects of lumbar belts (e.g. increased mechanical stiffness).

EFFICACY OF WRIST STRATEGY COACHING ON HANDSTAND PERFORMANCES IN NOVICES: INVERTING EXPLICIT AND IMPLICIT LEARNING OF SKILL-RELATED MOTOR TASKS

In gymnastics, mainstream handstand coaching emphasizes developing an aligned rigid body configuration, frequently leaving wrist-controlled balance work to implicit learning. However, skill-related motor behavioral research suggests the wrists to primarily contribute postural control in handstands. Considering recent research on handstands revealing experience-dependent motor behavior, the present study aimed to examine motor learning effects of explicit wrist usage coaching on handstand performances in skilled and less skilled novices. Therefore, twenty-five volunteering sport students served as participants completing a three-week training intervention which solely and explicitly addressed successful wrist usage during handstand. A video-tutorial introducing participants to the wrist strategy of hand balance preceded five practical training sessions that all neglected providing explicit postural advice. Participants performed three handstands on a plane gymnastics mat prior to (pre-test) and after (post-test) completing the training intervention. Standardized video recordings of each trial allowed retrospective group assignment (skilled and less skilled novices) based on pre-test mean balance times. With this, balance times, expert assessments (postural execution and balance control strategies) and goniometric analyses of shoulder and hip joint angles served to detect practical changes in handstand performances. Enhanced balance times as well as increased scores for postural execution and balance control strategies were revealed for less skilled novices (p &lt; .05), but not for skilled novices (p &gt; .05). Furthermore, in both groups changes in shoulder and hip joint angles failed significance. In conclusion, present findings suggest practitioners to make entirely unexperienced handstand learners explicitly aware of the wrist strategy’s operating principle.

Effects of Ankle Bracing on Postural Sway

Ankle bracing can alter postural control strategies during static and dynamic tasks, theoretically through mechanical constraint of the ankle joint and/or sensorimotor reorganization. While a majority of studies have focused on center of pressure (COP) characteristics or clinical tests of balance to explore this theory, fewer studies have investigated sway characteristics of the center of mass (COM). Additionally, the effects of various styles of ankle braces on postural sway remains inconclusive. Assessing the effects of ankle bracing on postural sway could provide additional insight into potential systemic motor adaptations that occur in response to ankle constraint. PURPOSE: Examine effects of lace-up and semi-rigid bracing on postural sway characteristics during a quiet-standing task. METHODS: Thirty-five adults between the ages of 18-30yrs (height: 1.72 ± 0.1m; mass: 75.49 ± 18kg) participated in the study. Participants performed a single one-minute trial of quiet-standing during each of the following conditions: No brace (NB), lace-up brace (LB), and semi-rigid brace (SRB). A ten-camera motion capture system was utilized to capture lower extremity positon. To assess postural sway, mediolateral (ML) and anteroposterior (AP) lower extremity COM trajectories were extracted, and root-mean-square deviation (RMSx, RMSy) and velocity (RMSvx, RMSvy) of the COM were calculated. Repeated-measures ANOVAs were employed to assess differences in postural sway measures across all conditions. RESULTS: Analysis revealed a significant main effect for RMSy (F = 7.061; p < .01). Pairwise comparisons indicated that RMSy was significantly lower in the SRB condition (1.770±1.698mm) compared to C (2.182 ±1.515mm) (p < .01). CONCLUSION: Results from study indicate that subjects exhibited an altered AP postural sway pattern when a semi-rigid brace is applied. These findings align with previous research reporting reduced AP COP excursions with ankle bracing during quiet-standing. Altered sway patterns with ankle bracing appears to support the presence of sensorimotor reorganization, possibly due to altered proprioceptive and/or haptic feedback stemming from greater mechanical constraint of the ankle joint.

Improved study on position measurement system for linear motor applied in electromagnetic launch system

The linear motor applied in electromagnetic emission system uses a closed loop position control strategy, which needs a set of position measurement system with high reliability, high resolution and integration to achieve real-time acquisition and analysis of position signals. The existing position controller is based on the simple logic chip design without memory function, and does not have the storage analysis and preprocessing function to position signals. Therefore, the system has insufficient scalability, low integration and reliability. Aiming at the improvement of the existing position measurement system, an intelligent position measurement system integrating the functions of position signals acquisition, processing and uploading, data storage and analysis is proposed in this paper, and its working principle and system composition are discussed in detail. The position, speed and acceleration obtained on the electromagnetic emission platform are in good agreement with the expected value of the system. As results, the feasibility and accuracy of the improved integrated intelligent position measurement system are verified, and the control performance of the system is also satisfied well, which can be good guidance and reference for subsequent engineering practice.

Multisegmented ankle-foot kinematics during gait initiation in ankle sprains and chronic ankle instability

BackgroundIndividuals with lateral ankle sprain and chronic ankle instability have impaired postural control and altered motor strategies during walking. However, little is known regarding foot mechanics during gait. The purpose of this study was to compare three-dimensional multisegmented ankle-foot kinematics during stance phase following gait-initiation in acute lateral ankle sprain (Ankle-sprain), chronic ankle instability (Chronic-instability), Coper, and Control groups. Methods80 recreationally-active individuals (Control: n = 22, Coper: n = 21, Ankle-sprain: n = 17, Chronic-instability: n = 20) participated. Three-dimensional kinematics of the hallux, medial forefoot, lateral forefoot, medial midfoot, lateral midfoot, and rearfoot on shank were collected during the stance phase following gait initiation using an electromagnetic motion capture system. The average joint excursions of 10 steps were normalized to 101 points and analyzed using Statistical Parametric Mapping ANOVA and post hoc t-tests comparing Coper, Ankle-sprain, or Chronic-instability versus Control groups. Secondary analysis was performed comparing Chronic-instability versus Coper groups. FindingsThe Ankle-sprain group had up to 4.1° more rearfoot inversion during midstance (mean difference: 3.1°) from 42 to 49% of stance phase compared to healthy controls. The Chronic-instability group had up to 5.3° more rearfoot inversion (mean difference: 3.6°) from 34% to 91% of stance phase compared to controls. There were no further statistical differences found between Chronic-instability and Copers, other planes, or segments of the ankle-foot complex. InterpretationAnkle-sprain and Chronic-instability groups demonstrated more rearfoot inversion compared to controls with no differences in midfoot or forefoot mechanics. Clinicians and researchers should include interventions that control inversion and increase eversion following lateral ankle sprain.

Event-Triggered Adaptive Attitude Tracking Control for Spacecraft With Unknown Actuator Faults

This paper is devoted to attitude tracking control of fractionated spacecraft with wireless communication. We consider the practical case that the spacecraft suffers from uncertain inertia parameters, external disturbances, and even unknown and time-varying actuator faults. Within the framework of the backstepping method, a novel event-triggered adaptive fault-tolerant control scheme is proposed. In our design, an event-triggering mechanism is introduced to determine the time instants for communication, which successfully avoids continuous communication and Zeno phenomenon. Then, with the aid of a bound estimation approach and a smooth function, the impacts of the actuator faults, as well as the network-induced error, are effectively compensated for. Moreover, by employing the prescribed performance control technique, it is shown that the attitude tracking errors can converge to predefined arbitrarily small residual sets with prescribed convergence rate and maximum overshoot, no matter if there exist unknown actuator faults. Compared with conventional adaptive attitude control schemes, the proposed scheme significantly reduces the communication burden, while providing high reliability and stable, rapid, and accurate response for attitude maneuvers. Simulation results are presented to illustrate the effectiveness of the proposed scheme.