scholarly journals Lidar-based surface following control for unmanned aerial vehicles

2021 ◽  
Author(s):  
Devin Simms
Keyword(s):  
Potential Field ◽  
Tracking Error ◽  
Vertical Surface ◽  
Curved Surface ◽  
Control Technique ◽  
Flat Surfaces ◽  
Field Control ◽  
Superior Surface ◽  
Axis Parallel ◽  
Wall Following

A simulation study is performed on a quadcopter which uses a LIDAR sensor to allow a quadcopter to navigate along and maintain a set distance from an unknown vertical surface. The dynamic equations of a quadcopter are linearized about the hovering equilibrium. For the purpose of design, all surfaces are assumed to be flat and any variations in shape are considered to be disturbances. The design process begins with the development of a potential field control design to allow the quadcopter to autonomously follow a flat surface, while maintaining a desired distance from the surface. To allow the quadcopter to follow a curved surface, the potential field technique is modified to maintain the xb axis parallel to the surface. Finally a wall following technique that directly uses the minimum range measurement to maintain the distance from the surface is developed. To simulate the control designs, a non-linear quadcopter model is used along with a model of a 2D scanning LIDAR sensor. The potential field control technique tracks flat surfaces with no steadystate error, though when curved surface following is added, a tracking error problem occurs due to measurement noise. The wall following design proves to be the superior surface following technique with greater robustness to steady-state error and results in relatively small tracking errors when navigating sinusoidal surfaces and corners.

scholarly journals Lidar-based surface following control for unmanned aerial vehicles

2021 ◽  
Author(s):  
Devin Simms
Keyword(s):  
Potential Field ◽  
Tracking Error ◽  
Vertical Surface ◽  
Curved Surface ◽  
Control Technique ◽  
Flat Surfaces ◽  
Field Control ◽  
Superior Surface ◽  
Axis Parallel ◽  
Wall Following

A simulation study is performed on a quadcopter which uses a LIDAR sensor to allow a quadcopter to navigate along and maintain a set distance from an unknown vertical surface. The dynamic equations of a quadcopter are linearized about the hovering equilibrium. For the purpose of design, all surfaces are assumed to be flat and any variations in shape are considered to be disturbances. The design process begins with the development of a potential field control design to allow the quadcopter to autonomously follow a flat surface, while maintaining a desired distance from the surface. To allow the quadcopter to follow a curved surface, the potential field technique is modified to maintain the xb axis parallel to the surface. Finally a wall following technique that directly uses the minimum range measurement to maintain the distance from the surface is developed. To simulate the control designs, a non-linear quadcopter model is used along with a model of a 2D scanning LIDAR sensor. The potential field control technique tracks flat surfaces with no steadystate error, though when curved surface following is added, a tracking error problem occurs due to measurement noise. The wall following design proves to be the superior surface following technique with greater robustness to steady-state error and results in relatively small tracking errors when navigating sinusoidal surfaces and corners.

scholarly journals Robust Current Predictive Control-Based Equivalent Input Disturbance Approach for PMSM Drive

Electronics ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1034 ◽  
Author(s):  
Xudong Liu ◽  
Qi Zhang
Keyword(s):  
Predictive Control ◽  
Permanent Magnet Synchronous Motor ◽  
Tracking Error ◽  
Current Control ◽  
Control Technique ◽  
Current Loop ◽  
Input Disturbance ◽  
Current Controller ◽  
Simulation And Experiment ◽  
Equivalent Input Disturbance

The implementation and experimental validation of current control strategy based on predictive control and equivalent input disturbance approach is discussed for permanent magnet synchronous motor (PMSM) control system in the paper. First, to realize the current decoupling control, the deadbeat predictive current control technique is adopted in the current loop of PMSM. Indeed, it is well known that the traditional deadbeat current control cannot completely reject the disturbance and realize the zero error current tracking control. Then, according to the model uncertainties and the parameter variations in the motor, an equivalent input disturbance approach is introduced to estimate the lump disturbance in the system, which will be used in the feed-forward compensation. Thus, a compound current controller is designed, and the proposed algorithm reduces the tracking error caused by the disturbance; the robustness of the drive system is improved effectively. Finally, simulation and experiment are accomplished on the control prototype, and the results show the effectiveness of the proposed current control algorithm.

scholarly journals Self-Adaptive Asymmetrical Artificial Potential Field Approach Dedicated to the Problem of Position Tracking by Nonholonomic UAVs in Windy Enivroments

2021 ◽  
Vol 15 (1) ◽  
pp. 37-46
Author(s):  
Cezary Kownacki
Keyword(s):  
Potential Field ◽  
Velocity Vector ◽  
Tracking Error ◽  
Potential Fields ◽  
Artificial Potential Field ◽  
Position Tracking ◽  
Wind Drift ◽  
Precise Position ◽  
Field Approach ◽  
Nonholonomic Robots

Abstract Artificial potential fields (APFs) are a popular method of planning and controlling the path of robot movement, including unmanned aerial vehicles (UAVs). However, in the case of nonholonomic robots such as fixed-wing UAVs, the distribution of velocity vectors should be adapted to their limited manoeuvrability to ensure stable and precise position tracking. The previously proposed local asymmetrical potential field resolves this issue, but it is not effective in the case of windy environments, where the UAV is unable to maintain the desired position and drifts due to the wind drift effect. This is reflected in the growth of position error, which, similar to the steady-state error in the best case, is constant. To compensate for it, the asymmetrical potential field approach is modified by extending definitions of potential function gradient and velocity vector field (VVF) with elements based on the integral of position tracking error. In the case of wind drift, the value of this integral increases over time, and lengths and orientations of velocity vectors will also be changed. The work proves that redefining gradient and velocity vector as a function of position tracking error integrals allows for minimisation of the position tracking error caused by wind drift.

scholarly journals A fast L1 adaptive constrained back-stepping controller using barrier Lyapunov function for anuncertain submersible vehicle

2021 ◽  
Author(s):  
Hossein Ahmadian ◽  
Mehdi Arefi ◽  
Alireza Khayatian ◽  
Allahyar Montazeri
Keyword(s):  
Adaptive Control ◽  
Lyapunov Function ◽  
Trajectory Tracking ◽  
Tracking Error ◽  
Control Technique ◽  
Remotely Operated Vehicle ◽  
Pass Filter ◽  
Low Pass Filter ◽  
L1 Adaptive Control ◽  
Barrier Lyapunov Function

Abstract In this paper, a new L1 adaptive back-stepping controller based on the barrier Lyapunov function (BLF) is proposed to respect the position and velocity constraints usually imposed in designing Euler-Lagrange systems. The purpose of this investigation is to improve different aspects of a conventional L1 adaptive control. More specifically, the modified controller has a lower complexity by removing the low-pass filter from the design procedure. The performance of the controller is also enhanced by having a faster convergence speed and increased robustness against nonlinear uncertainties and disturbances arising in practical applications. The proposed scheme is evaluated on two different Euler-Lagrange systems, i.e. a 6-DOF remotely operated vehicle (ROV) and a single-link manipulator. The results for the new back-stepping design are assessed in both scenarios in terms of settling time, percentage of overshoot, and trajectory tracking error. The results confirm that both tracking and state estimation errors for position and velocity outputs outperform the standard L1 adaptive control technique. The results also demonstrate the high performance of the proposed approach in removing the matched nonlinear time-varying disturbances and dynamic uncertainties and a good trajectory tracking despite the uncertainty on the input gain of the system.

scholarly journals Direct Digital Design of PIDF Controllers with ComPlex Zeros for DC-DC Buck Converters

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 36 ◽  
Author(s):  
Stefania Cuoghi ◽  
Lorenzo Ntogramatzidis ◽  
Fabrizio Padula ◽  
Gabriele Grandi
Keyword(s):  
Transfer Function ◽  
Tracking Error ◽  
Design Procedure ◽  
Buck Converter ◽  
Digital Design ◽  
Control Technique ◽  
Infinite Impulse Response ◽  
Buck Converters ◽  
Pass Filter ◽  
Low Pass Filter

This paper presents a new direct digital design method for discrete proportional integral derivative PID + filter (PIDF) controllers employed in DC-DC buck converters. The considered controller structure results in a proper transfer function which has the advantage of being directly implementable by a microcontroller algorithm. Secondly, it can be written as an Infinite Impulse Response (IIR) digital filter. Thirdly, the further degree of freedom introduced by the low pass filter of the transfer function can be used to satisfy additional specifications. A new design procedure is proposed, which consists of the conjunction of the pole-zero cancellation method with an analytical design control methodology based on inversion formulae. These two methods are employed to reduce the negative effects introduced by the complex poles in the transfer function of the buck converter while exactly satisfying steady-state specifications on the tracking error and frequency domain requirements on the phase margin and on the gain crossover frequency. The proposed approach allows the designer to assign a closed-loop bandwidth without constraints imposed by the resonance frequency of the buck converter. The response under step variation of the reference value, and the disturbance rejection capability of the proposed control technique under load variations are also evaluated in real-time implementation by using the Arduino DUE board, and compared with other methods.

Nanostructuring Curved Surfaces Using a Flexible Stamp

2009 ◽  
Author(s):  
Bahador Farshchian ◽  
JaeJong Lee ◽  
Sunggook Park
Keyword(s):  
Hot Embossing ◽  
Curved Surface ◽  
Curved Surfaces ◽  
Pmma Substrate ◽  
Pdms Stamp ◽  
Flat Surfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Metallic Object ◽  
Planar Substrates

We report on a simple and effective process that allows direct imprinting of micro- and nanostructures on non-flat surfaces. A thin polydimethylsiloxane (PDMS) stamp having micro/nanogratings was placed between a metallic bar with a trapezoidal cross section or a metallic pellet and a flat polymethyl methacrylate (PMMA) substrate, followed by hot embossing at 200°C. During the hot embossing process, the metallic bar/pellet is pushed into the PMMA sheet forming a millimeter scale channel or a curved surface. Due to the presence of the PDMS stamp between the metallic object and the substrate, micro/nanostructures are produced into the channel or over the curved surface. With this method, we have successfully demonstrated micro- and nanostructures down to 300 nm wide gratings on non-flat substrates, as confirmed by scanning electron microscopy and atomic force microscopy. The process so developed will fill the gap in current micro- and nanofabrication technologies in that most of the technologies allow for patterning only on planar substrates.

Coordinate Control of Energy-Saving Programmable Valves

2003 ◽  
Author(s):  
Song Liu ◽  
Bin Yao
Keyword(s):  
Energy Saving ◽  
Controller Design ◽  
Tracking Error ◽  
Adaptive Robust Control ◽  
Control Technique ◽  
Coordinate Control ◽  
Side Pressure ◽  
Programmable Valve ◽  
Pressure Dynamics ◽  
Programmable Valves

The energy-saving programmable valve, a unique combination of five independent cartridge valves, not only decouples the control of meter-in and meter-out flows but also provides the ability of precisely controlling cross-port flows for energy-saving purpose. Our previous works have already shown that the tremendous control flexibility gained by the proposed hardware re-configuration enables one not only to achieve precision control of the cylinder motion but also to decrease the energy usage significantly through actively utilizing the potential and kinetic energy of the load in accomplishing certain tasks such as smooth stopping. However, the control of such an essentially multi-input valve system to achieve the above objectives is far from trivial. In our previous works, a constant off-side pressure was assumed in the controller design for simplicity. This assumption may not be realistic in certain circumstances where the off-side pressure may vary from the assumed constant pressure significantly, especially right after the change of working mode. As a result, though the controller design is simplified, larger tracking error results during the transients. This paper presents an improved way to coordinately control the five independent valves by incorporating the off-side pressure dynamics into the controller design. The Adaptive Robust Control technique is applied to guarantee the stability and tracking performance in the presence of large system parameter variations and disturbances. Simulation and experimental results are shown to verify the much improved control performance of the presented coordinate control strategy.

scholarly journals A Novel Linear Active Disturbance Rejection Control Design for Air-Breathing Supersonic Vehicle Attitude System with Prescribed Performance

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Chao Ming ◽  
Xiaoming Wang
Keyword(s):  
Disturbance Rejection ◽  
Tracking Error ◽  
Transient State ◽  
Control Technique ◽  
Active Disturbance Rejection Control ◽  
Air Breathing ◽  
Prescribed Performance ◽  
Active Disturbance Rejection ◽  
Disturbance Rejection Control ◽  
Attitude Controller

This paper investigates the design problem of the attitude controller for air-breathing supersonic vehicle subject to uncertainties and disturbances. Firstly, the longitudinal model is established for the attitude controller design which is devised as a strict feedback formulation, and a transformed tracking error is derived with the prescribed performance control technique such that it can limit the tracking error to a predefined region. Then, a novel linear active disturbance rejection control scheme is proposed for the attitude system to enhance the steady-state and transient-state performances by incorporating the transformed tracking error. On the basis of the Lyapunov stability theorem, the convergence and stability characteristics are both rigorously proved for the closed-loop system. Finally, extensive contrast simulations are conducted to demonstrate the effectiveness, robustness, and advantage of the proposed control strategy.

A Hybrid Optimal Control Strategy for a Smart Prosthetic Hand

2009 ◽  
Author(s):  
Cheng-Hung Chen ◽  
D. Subbaram Naidu ◽  
Alba Perez-Gracia ◽  
Marco P. Schoen
Keyword(s):  
Optimal Control ◽  
Fuzzy Inference ◽  
Tracking Error ◽  
Three Dimensional ◽  
Control Technique ◽  
Prosthetic Hand ◽  
Linear Quadratic ◽  
Optimal Control Strategy ◽  
Linear Quadratic Optimal Control ◽  
Inference System

This paper presents a hybrid of a soft computing or control technique of adaptive neuro-fuzzy inference system (AN-FIS) and a hard computing or control technique of the hybrid finite-time linear quadratic optimal control for a two-fingered (thumb and index) prosthetic hand. In particular, the ANFIS is used for inverse kinematics, and the optimal control is used to minimize tracking error utilizing feedback linearized dynamics. The simulations of this hybrid controller, when compared with the proportional-integral-derivative (PID) controller showed enhanced performance. Work is underway to extend this methodology to a five-fingered, three-dimensional prosthetic hand.

On a novel equivalent control-based adaptive sliding mode approach for autopilot design of BTT missiles

2016 ◽  
Vol 40 (2) ◽  
pp. 578-590 ◽  
Author(s):  
Zongyi Guo
Keyword(s):  
Finite Time ◽  
Sliding Mode ◽  
Dynamic Performance ◽  
Tracking Error ◽  
Control Technique ◽  
Adaptive Sliding Mode Control ◽  
Sliding Surface ◽  
Adaptive Sliding Mode ◽  
Equivalent Control ◽  
Btt Missile

This paper presents a novel equivalent control-based adaptive sliding mode control (EASMC) approach for designing the autopilot of a bank-to-turn (BTT) missile under model uncertainties and external disturbances. The sliding surface is constructed with a tracking error between the real attitude angle and the reference command. The equivalent control technique works as a mechanism for the gains over-bounded by uncertainties and this information is implemented in the adaption progress. The method guarantees that the sliding surface reaches zero in finite time and the error tracks the command value asymptotically. The advantage of this method is that the gains will be adapted to counteract uncertainties and enable the control deflection magnitude to be reduced to the minimum value, keeping the property of a finite-time convergence. The skill in choosing the gains is also given in this paper. Simulation results demonstrate that the approach proposed is able to improve the dynamic performance and robustness of a BTT missile system.

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