Depth Control System Research Articles

Complementary Constrained Model Predictive Depth Control of a Hybridly-Actuated Submarine Drifter

The submarine drifter is a novel Lagrangian-based observation platform to explore the ocean, but its precise and rapid depth control system design is still an open issue. The major challenge would be the complex hybrid actuation system, which contains anisotropic characteristics and switching issues. In this paper, we proposed an modified complementary constrained model predictive control (MCC-MPC) scheme to meet the metrics. The scheme reformulates complex drifter and hybrid actuation system dynamics into a solvable system with complementary constraints. The nonlinear component inside the system is approximated by applying a sgn-sigmoid approximation function for the sake of linearization and computation. Then the customized online optimizer predicts the system dynamics with complementary constraints and computes the optimal control outputs in the finite horizon in an iterative loop. The validation results prove that the proposed controller can effectively control the submarine drifter to achieve the desired depth and the key metrics are 10×, 4×, and 2× better than conventional PID control, disturbance observer-based control, and conventional MPC methods, respectively.

Model Predictive Control-Based Depth Control in Gliding Motion of a Gliding Robotic Dolphin

This article proposes a model predictive control (MPC)-based depth control system for the gliding motion of a gliding robotic dolphin. An injector-based buoyancy-driven mechanism is employed to achieve more precise control of net buoyancy. In the system, a novel framework of depth control is proposed on the basis of a simplified model, including a depth controller with improved MPC, a heading controller with velocity-based proportional-integral-derivative, and a sliding mode observer. Extensive simulation and experimental results demonstrate the effectiveness of the proposed control methods. In particular, a variety of slider-based experiments are also conducted to explore the performance of a movable slider in the depth control so as to better govern the gliding angle. The results obtained reveal that it is feasible to realize regular gliding angles via regulating the slider, which offers promising prospects for bio-inspired gliding robots playing a key role in ocean exploration.

Autonomous underwater vehicle depth control based on an improved active disturbance rejection controller

Large fluctuation, large overshoot, and uncertain external disturbance that occur when an autonomous underwater vehicle is in deep motion are difficult to address using the traditional control method. An optimal control strategy based on an improved active disturbance rejection control technology is proposed to enhance the trajectory tracking accuracy of autonomous underwater vehicles in actual bathymetric operations and resist external and internal disturbances. First, the depth motion and mathematical models of an autonomous underwater vehicle and propeller are established, respectively. Second, the control rate of the extended state observer and the nonlinear error feedback of the traditional active disturbance rejection control are improved by using a new nonlinear function. The nonlinearity, model uncertainty, and external disturbance of the autonomous underwater vehicle depth control system are extended to a new state, which is realized by an improved extended state observer. Third, the improved nonlinear state error feedback is used to suppress residual errors and provide high-quality control for the system. Simulation and experimental results show that under the same parameters, the traditional active disturbance rejection control has a small overshoot, fast tracking ability, and strong anti-interference ability. The optimized active disturbance rejection control and traditional active disturbance rejection control are applied to the deep-variation motion of autonomous underwater vehicles. Results show that the proposed optimal control strategy is not only simple and feasible but also demonstrates good control performance.

Influence Factors Analysis of Ultrasonic Detection Gravel Terrain Elevation Precision Based on Orthogonal Experiment

In the depth control system of clean-up collect mechanical, the influence factors of ultrasonic detection accuracy such as sensor frequency, installation height, marching speed and earth’s surface roughness are analysed by orthogonal experiment through range and variance analysis methods. The results show that installation angle and marching speed are the most important influencing factors, the installation height and surface roughness have no significant effect. In the practical application, the installation angle and marching speed should be considered firstly, the sensor frequency and installation height can be adjusted according to the terrain.

A practical effort to equip tractor-implement with fuzzy depth and draft control system

This paper describes an applied research established in response to farmer's request for improvement of performance of tractor-implement in tillage operations. An effort for decrement of variations in plowing depth as well as increment of tractive efficiency of a moderate power tractor in tillage operations with mounted implements led to development of a fuzzy depth and draft control system for tractor-implement. The fuzzy control system consisted of an electrical sensing, control, and electro-hydraulic actuator unit. A command set including four fuzzy rules were programmed for the control unit. To determine merits of the fuzzy control system, the field experiments were carried out at three levels of plowing depth (10, 20 and 30 cm), forward speed (2, 4 and 6 km/h), and implement types (moldboard, disk, and chisel plow) utilizing the system mounted on a tractor (MF-399). Some performance parameters of tractor-implement were then determined in the field experiments. The results indicated application of the fuzzy control system rather than available draft control system of the tractor resulted in increment of tractive efficiency and overall energy efficiency up to 20 and 73%, respectively. Meanwhile, plowing depth error, driving wheel slip, and fuel consumption decreased up to 53, 34 and 34%, respectively. The performance of the fuzzy control system was not sensitive to implement type and plowing depth, while it was influenced by forward speed (P ≤ 0.01). The fuzzy control system adequately improved performance of tractor-implement in tillage operations and satisfied farmer's requirements. Hence, it is recommended to industrialize and commercialize the fuzzy control system in order to mount it on any moderate power tractor.

Разработка и исследование системы управления движением подводного аппарата в вертикальной плоскости. Синтез контура системы управления глубиной погружения подводного аппарата

Разработка и исследование системы управления движением подводного аппарата в вертикальной плоскости. Синтез контура системы управления глубиной погружения подводного аппарата

Depth control for storage tank in-service inspection robot based on artificial intelligence control

PurposeThe purpose of this paper is to propose a buoyancy-gravity adjustment device and a fuzzy intelligent controller for the depth control of a storage tank in-service inspection robot.Design/methodology/approachThe structure of the robot is first designed based on the construction of the bottom of a crude oil tank and explosion-proof requirements. The buoyancy-gravity adjustment system is used to control the vertical movement of the robot. The motion analysis of the robot indicates that the diving or rising process is influenced by hydrodynamic force and umbilical cord tension. Considering the nonlinear model in-depth control, a fuzzy intelligent controller is proposed to address the depth control problem. The primary fuzzy controller is used to compensate for initial error with fast response. The secondary fuzzy controller is activated by an intelligent switch to eliminate the steady error.FindingsThe proposed fuzzy controller can better solve the complicated hydrodynamic problem of the coupling of umbilical cord and the robot during depth control by classifying the error values of depth, velocity and acceleration.Originality/valueThe buoyancy-gravity adjustment device and the depth control system of the robot can move through the heating coils by safe and accurate diving or rising.

Parametric synthesis of a robust controller on a base of mathematical programming method

Considered paper is dedicated to deriving sufficient conditions, linking root indices of robust control quality with coefficients of interval characteristic polynomial, on the base of mathematical programming method. On the base of these conditions, a method of PI- and PID-controllers, providing aperiodic transient process with acceptable stability degree and, subsequently, acceptable setting time, synthesis was developed. The method was applied to a problem of synthesizing a controller for a depth control system of an unmanned underwater vehicle.

Modelling of depth stabilization and submerging of tethered underwater garage in conditions of sea oscillating motion

The paper is dedicated to examining dynamics of a submersible underwater garage in conditions of significant sea oscillation. During the considered research, the mathematical model of the electromechanical depth control system, considering interval parametric uncertainty of the system and distribution of tether mass, was developed. An influence of sea oscillation on submerging underwater garages and their depth stabilization processes was analyzed.

Automatic depth control system for a no-till seeder

Sowing depth has an important impact on the performance of a no-till seeder. The seeds should be placed at optimal depth for rapid germination and emergency. To compensate the spatial variation in soil type and conditions, an automatic depth control system was designed, which consisted of a deformation sensor, an actuator and a controller. The deformation sensor was made of polyvinylidene fluoride (PVDF) film, which was fixed on the inner surface of the gauge wheel, and the output voltage was determined by the deformation of the wheel. Two models of the PVDF sensor with a tiled shape and an arched shape were set up to analyze the relationship between the output signal and the wheel deformation. In the experiments, the relationship between the output voltage and gauge wheel deformation was obtained, and the results were in accord with the model analysis results. The voltage of both sensors increase with the augment of deformation, the arched sensor was more sensitive than the tiled one. The arched sensor embedded in the control system was able to maintain the desired seeding depth within tolerance ±8 mm at driving speed of 2.78 m/s, which can satisfy the agronomic requirements for the no-till seeder. Keywords: no-till seeder, sowing depth, control system, polyvinylidene fluoride (PVDF) film, sensor DOI: 10.25165/j.ijabe.20181101.3229 Citation: Zhao J L, Zhu L T, Jia H L, Huang D Y, Guo M Z, Cong Y J. Automatic depth control system for a no-till seeder. Int J Agric & Biol Eng, 2018; 11(1): 115–121.

Automatic depth control system for a no-till seeder

Automatic depth control system for a no-till seeder

Seed drill depth control system for precision seeding

An adequate and uniform seeding depth is crucial for the homogeneous development of a crop, as it affects time of emergence and germination rate. The considerable depth variations observed during seeding operations - even for modern seed drills - are mainly caused by variability in soil resistance acting on the drill coulters, which generates unwanted vibrations and, consequently, a non-uniform seed placement. Therefore, a proof-of-concept dynamic coulter depth control system for a low-cost seed drill was developed and studied in a field experiment. The performance of the active control system was evaluated for the working speeds of 4, 8 and 12 km h−1, by testing uniformity and accuracy of the coulter depth in relation to the target depth of −30 mm. The evaluation was based on coulter depth measurements, obtained by coulter position sensors combined with ultrasonic soil surface sensors. Mean coulter depth offsets of 3.5, 5.3 and 6.3 mm to the target were registered for the depth control system, compared to 8.0, 9.1 and 11.0 mm without the control system for 4, 8 and 12 km h−1, respectively. However, speed did not affect the coulter depth significantly. The control system optimised coulter depth accuracy by 15.2% and at 95% confidence interval it corresponded to an absolute reduction in the coulter depth confidence span of 10.4 mm. The spatial variability, due to variation in soil mechanical properties was found to be ±8 mm, across the blocks for the standard drill and when activating the coulter depth control system this variability was reduced to ±2 mm. The system with the active control system operated more accurately at an operational speed of 12 km h−1 than at 4 km h−1 without the activated control system.

SIMULATION OF AUTOMATIC CONTROL SYSTEMS OF TILLAGE UNITS

The studies were performed to improve workflow of hydraulic automatic control systems of the tillage units. Tillage quality should not deteriorate. Working bodies of tillage machines have to be moved automatically. Automated devices can be separated into two groups: direct and indirect action. It is preferable to indirect action. The article presents analysis of automatic devices used into tillage machines. Automatic control systems can be hydraulic, electro-hydraulic and pneumatic. Mechanical systems are not effective. Hydraulic systems are cheaper electric and pneumatic. They provide best of energy and quality indicators of technological process of tillage. Automatic control systems are uses draft forces, hitch position, depth of the implement, speed, acceleration and other sensors. Method of computer modeling and optimization of hydraulic automatic control systems of tillage units was developed. Results of computer modeling of hydraulic automatic control systems help to select direction of improving quality and energy indicators of technological process of tillage. Optimized combine implement depth and draft control system of arable unit allow reducing deviation the draft force of the plow; deviation of the depth of plowing is equal to or smaller than agro-technical requirements. Deviation of the draft force was decreased to 13.5 % for deviation specific soil resistance - 20 %, depth of plowing - 0.21 m, deviation of the depth of plowing - 0.019 m (9 %). Deviation of the depth of plowing may be decreased to 0.010 m (4,8 %), but deviation of the draft force shell be increased up to 16.2%. Optimized hydraulic automatic control system of garden tiller with a trapezoidal mechanism leaves smaller untreated soil area from 1.37-1.46 times.

Controlling the Depth of Microchannels Formed during Rolling-based Surface Texturing

The geometric dimension and shape of microchannels that are formed during surface texturing are widely studied for applications in flow control, and drag and friction reduction. In this research, a new method for controlling the deformation of U channels during micro-rolling-based surface texturing was developed. Since the width of the U channels is almost constant, controlling the depth is essential. A calibration procedure of initial rolling gap, and proportional-integral PI controllers and a linear interpolation have been applied simultaneously to control the depth. The PI controllers drive the position of the pre-U grooved roll as well as the rolling gap. The relationship between the channel depth and rolling gap is linearized to create a feedback signal in the depth control system. The depth of micro channels is studied on A2021 aluminum lamina surfaces. Overall, the experimental results demonstrated the feasibility of the method for controlling the depth of microchannels.

Development of Seeding Depth Control System for Conservation Tillage Cultivation

Development of Seeding Depth Control System for Conservation Tillage Cultivation

English

Remotely Operated Vehicles are underwater robots designed specifically for surveillance, monitoring and collecting data for underwater activities. In the underwater vehicle industries, the thruster is an important part in controlling the direction, depth and speed of the ROV. However, there are some ROVs that cannot be maintained at the specified depth for a long time because of disturbance. This paper proposes an auto depth control using a thruster system. A prototype of a thruster with an auto depth control is developed and attached to the previously fabricated UTeM ROV. This paper presents the operation of auto depth control as well as thrusters for submerging and emerging purposes and maintaining the specified depth. The thruster system utilizes a microcontroller as its brain, a piezoresistive strain gauge pressure sensor and a DC brushless motor to run the propeller. Performance analysis of the auto depth control system is conducted to identify the sensitivity of the pressure sensor, and the accuracy and stability of the system. The results show that the thruster system performs well in maintaining a specified depth as well as stabilizing itself when a disturbanceoccurs even with a simple proportional controller used to control the thruster, where the thruster is an important component of the ROV.

Design of Auxiliary Depth-control System for Micro-tiller

When the micro-tiller is applied to agricultural tillage on farmland in the hilly rural areas of southwestern China, there are two major issues. One is highly variable cutting depth; the other is the quite difficult manual labor. In order to improve the tillage quality of the micro-tiller and relieve the operator's manual labor, Auxiliary Depth-control System (ADS), which mainly consists of a detector, a controller, an actuator and a display interface, is designed in this paper. It is used to display real-time cutting depth and control the reciprocating motion of the resistance rod of the micro-tiller. The field tests showed that ADS improved the consistency of cutting depth because the coefficient of variation of the consistency of cutting depth decreased from 11.59% by the micro-tiller with traditional resistance rod to 5.82% by that with ADS, meeting the agronomic requirement of fewer than 10%. Meanwhile, the manual labor required was alleviated as labor intensity index decreased from 20 to 18 after usage of ADS in the micro-tiller. That could prove the significance of ADS in future micro-tiller design.

박막 절단용 PZT 구동 미세깊이 조절 장치의 특성

This study aims to develop a PZT ‐driven depth adjustment device with a flexure hinge and to investigate its static/dynamic characteristics. This device will be applied to rapidly and accurately trace a flat surface with slight waviness of up to several hundreds of micrometers in magnitude. One typical example is to cut a film coated on a steel plate. A depth control system composed of PMAC, PZT/PZT amplifier, flexure hinge/knife, and laser displacement sensor is implemented on a desktop three‐axis machine and an actual cutting test is conducted on a steel workpiece with a sinusoidal ‐wavy surface. It is verified that the dynamic characteristics of the device limit the maximum cutting speed and depth precision. Received 21 October 2014Revised 1 December 2014Accepted 3 December 2014

MOOS-IvP를 이용한 무인잠수정 제어기 개발의 효용성

This paper demonstrates the benefit of using MOOS-IvP in the development of control system for Unmanned Underwater Vehicles(UUV). The demand for autonomy in UUVs has significantly increased due to the complexity in missions to be performed. Furthermore, the increased number of sensors and actuators that are interconnected through a network has introduced a need for a middleware platform for UUVs. In this context, MOOS-IvP, which is an open source software architecture, has been developed by several researchers from MIT, Oxford University, and NUWC. The MOOS software is a communication middleware based on the publish-subscribe architecture allowing each application to communicate through a MOOS database. The IvP Helm, which is one of the MOOS modules, publishes vehicle commands using multi-objective optimization in order to implement autonomous decision making. This paper explores the benefit of MOOS-IvP in the development of control software for UUVs by using a case study with an auto depth control system based on self-organizing fuzzy logic control. The simulation results show that the design and verification of UUV control software based on MOOS-IvP can be carried out quickly and efficiently thanks to the reuse of source codes, modular-based architecture, and the high level of scalability.

Control System of Sand Milling Collection Machine Based on PLC

An engineering machine wireless control system is researched based on a diggings milling collection machine. The system consists of PLC, communications module, relays, touch screen, router and long-distance terminal. The ideas of PLC state of self-sustaining when host dropped, wireless control and local control redundancy, and control instructions prioritization are proposed to achieve the reliable operation of the system. The system with local control and wireless control has been applied on the sand milling collection machine and the wireless remote control of all operations has been realized with no instruction lost and misused. A mining engineering requires that the sand with the mine in the earth’s surface of about 2~5cm depth should be collected. Also, in order to realize the accurate collection to reduce the subsequent processing cost, it demands that the thick precision of the collection should be controlled within ±5mm. Considering that the milling collection is suitable for work of large-area sand collection and easier to meet the demand of the accurate control of the depth, the sand milling collection machine is researched. This machine is equipped with the milling collection unit and depth control system. It is able to conduct the sand collection experiment under the field condition.