Active compliant control enables to quickly and freely adjust the properties and dynamic behavior of interactions of mechanisms within certain limits. According to the emerging applications in many ...robotic fields and related areas, the number of publications has also strongly increased. This paper meets the need for a recent comprehensive review, including a profound and concise characterization and classification of compliant control approaches extending the basic concepts, hybrid and parallel force/position, impedance and admittance control, by a survey of their variants and combinations. It mainly focuses on individually operating, stiff, non-redundant systems. Unlike previous reviews, this work is based on a transparent and systematic literature search methodology, which can easily be adapted or updated by any reader, hence remaining enduringly up-to-date over time. Also, a novel selection scheme is proposed, which facilitates the choice of appropriate control approaches for given requirements, particularly for newcoming researchers to the field.
•A review on active compliant control focusing on rigid systems.•Based on a transparent and systematic literature research methodology.•Characterization of active compliant control concepts and many of their variants.•Basic concepts: Hybrid and parallel force/position, impedance and admittance control.•Schematics to guide novices in application specific selection of control approaches.
Motion control theory applied to multi-rotor aerial vehicles (MAVs) has gained attention with the recent increase in the processing power of computers, which are now able to perform the calculations ...needed for this technique, and with lower cost of sensors and actuators. Control algorithms of this kind are applied to the position and the attitude of MAVs. In this paper, we present a review of recent developments in position control and attitude control of multi-rotor aerial robots systems. We also point out the growth of related research, starting with the boom in multi-rotor unmanned aerial robotics that began after 2010, and we discuss reported field applications and future challenges of the control problem described here. The objective of this survey is to provide a unified and accessible presentation, placing the classical model of a multi-rotor aerial vehicle and the proposed control approaches into a proper context, and to form a starting point for researchers who are initiating their endeavors in linear/nonlinear position, altitude or attitude control applied to MAVs. Finally, the contribution of this work is an attempt to present a comprehensive review of recent breakthroughs in the field, providing links to the most interesting and most successful works from the state-of-the-art.
In this article, a kind of predictive control (PC) for permanent magnet synchronous motor (PMSM) rotor position control is introduced, and more stable and rapid performances are achieved comparing ...with other PCs. Nonlinear predictive control (NLPC) is shown to outperform the linear in terms of performance for nonlinear controlled plants because of containing nonlinear part and longer prediction horizons. A novel direct speed NLPC scheme for PMSM is presented based on this strategy. The response and reference signals are predicted with Taylor series expansion to guarantee the accuracy of the system. Prediction horizons are selected according to Shannon with its maximum value to eliminate steady-state error and delay between actual and reference signals. Furthermore, the proposed method is designed and analyzed in detail, and tested by simulations and experiments. Results with respect to the rotor position trace tracking, control performance, and weighting factors sensitivity demonstrate the efficiency of the proposed method.
An adaptive finite-time control scheme is developed for noncooperative spacecraft fly-around subject to input saturation, full-state constraints, dynamic couplings, parameter uncertainties, and ...disturbances. Different from traditional fly-around model based on C-W equation, the derived 6-DOF spacecraft fly-around model can be suitable for noncooperative case in close proximity. By using the backstepping control technique, an integrated adaptive finite-time control law is designed, in which the tan-type barrier Lyapunov function (BLF) is incorporated to handle the full-state constraints. Meanwhile, the unknown dynamic couplings, parameter uncertainties, and disturbances are attenuated effectively by using adaptive estimation technique and the adverse effects raised from input saturation are reduced by the designed saturation compensator. Based on the constructed BLF, it is shown that the designed adaptive finite-time controller can guarantee that full-state constraints are not breached, but also can drive relative position and attitude tracking errors into the accurate convergent regions with finite-time convergence. Finally, the performance and advantage of the designed adaptive finite-time control scheme are demonstrated by numerical simulations.
Nonlinear control systems presented in the form of differential inclusions with impulse or discontinuous positional controls are investigated. The formalization of the impulse-sliding regime is ...carried out. In terms of the jump function of the impulse control, the differential inclusion is written for the ideal impulse-sliding regime. The method of equivalent control for differential inclusion with discontinuous positional controls is used to solve the question of the existence of a discontinuous system for which the ideal impulse-sliding regime is the usual sliding regime. The possibility of the combined use of the impulse-sliding and sliding regimes as control actions in those situations when there are not enough control resources for the latter is discussed.
Magnetically actuated small-scale robots have great potential for numerous applications in remote, confined, or enclosed environments. Multiple small-scale robots enable cooperation and increase the ...operating efficiency. However, independent control of multiple magnetic small-scale robots is a great challenge, because the robots receive identical control inputs from the same external magnetic field. In this article, we propose a novel strategy of completely decoupled independent control of magnetically actuated flexible swimming millirobots. A flexible millirobot shows a crawling motion on a flat plane within an oscillating magnetic field. Millirobots with different magnetization directions have the same velocity response curve to the oscillating magnetic field but with a difference of phase. We designed and fabricated a group of up to four heterogeneous millirobots with identical geometries and different magnetization directions. According to their velocity response curves, an optimal direction of oscillating magnetic field is calculated to induce a desired velocity vector for the millirobot group, one of which is nonzero and the others are approximately zero. The strategy is verified by experiments of independent position control of up to four millirobots and independent path following control of up to three millirobots with small errors. We further expect that with this independent control strategy, the millirobots will be able to cooperate to finish complicated tasks.
To achieve high-precision position control for the active magnetic bearing high-speed flywheel rotor system (AMB-HFRS), a novel control strategy based on inverse system method and extended ...two-degree-of-freedom (2-DOF) proportional–integral–derivative (PID) controller is proposed in this study. First, the inverse system method is employed to decouple the AMB flywheel rotor system with strong non-linear and coupling, into four independent subsystems. Subsequently, extended 2-DOF PID controllers are used to regulate the decoupled subsystems, to obtain good performances of disturbance rejection and tracking simultaneously. In the extended 2-DOF PID controller, a differential signal is produced by a velocity observer to improve the ability of against noise. Finally, the characteristics of stability, tracking, disturbance rejection and robustness of the control strategy proposed are analysed in theory, and its ability and effectiveness to control the radial position of the AMB-HFRS are further studied by simulations and experiments. It is shown that the control strategy proposed can keep the AMB-HFRS suspending stably from static state to the speed of 24,000 rpm, has the advantages of good tracking, high disturbance rejection, strong robustness and good ability of against noise.
Automatic assembly equipment is the key to improving the efficiency and quality of workpiece assembly. The precision of assembly directly influences the overall quality of the assembled product. To ...optimise the position control accuracy in the automatic assembly equipment, a variable universe fuzzy proportional integral (VUFPI) controller optimised by the sparrow search algorithm (SSA) is developed in this paper. The developed controller adopts the SSA to adjust in real time the universe of the fuzzy controller according to the deviation of the servo system. The servo system model is established to evaluate the performance of the proposed SSA-VUFPI controller; furthermore, the SSA-VUFPI controller is implemented in the automatic assembly equipment for experimental evaluation. The analysis results demonstrate that the proposed SSA-VUFPI controller is capable of improving the anti-interference ability and position accuracy of the servo system compared to traditional PI, VUFPI, and currently used back propagation neural network proportional-integral-derivative (BP-PID), fractional-order PID (FOPID), and SSA-PID controllers. Moreover, it effectively improves the position accuracy of the workpiece and ultimately improves the quality of the assembly.
Conventional predictive position control (PPC) method balances the position, speed and current of permanent magnet synchronous machine with different weighting factors. However, tedious tuning work ...of weighting factors is needed. To simplify the tuning process, a cost function that includes the system position, and current information is constructed based on deadbeat control method. A novel method based voltage boundary is proposed to limit the current and speed simultaneously, the voltage regions corresponding to current and speed constraints are analyzed and the voltage duty cycle is further modified according to the voltage regions, the complex weighting factor turning work is avoided, the current and speed limits are easy to implement with proposed method and less position error can be achieved. Finally, the proposed method is experimentally compared with a conventional finite-control-set PPC method and a direct speed model predictive control method.
Predictive position control (PPC) method with long predictive horizon is an effective method to eliminate the cascade structure and improve the dynamic response for the permanent magnet synchronous ...motor (PMSM). However, traditional PPC method needs a time-consuming prediction process and does not always guarantee satisfactory position performance. In this article, a simplified constrained PPC method is proposed, the Laguerre functions are designed to construct the control trajectory of position system, which offers two control degrees to improve the position dynamic response and simplify programming of prediction process. Besides that, the optimization model with current constraints, speed constraints, and voltage constraints are constructed with the frame of Laguerre functions. The optimization model with constraints is solved with an optimal method and suboptimal method. The proposed PPC method is experimentally verified and compared with field-oriented control (FOC) method and a traditional PPC method, the results have proved that proposed method has excellent position performance and low calculation burden.
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