In this paper, the design, modeling and implementation of a novel spherical mobile robot is presented. The robot composes of a spherical outer shell made of a transparent thermoplastic material, two pendulums, two DC motors with gearboxes, two equipments for linear motion and two control units. It possesses four distinct motional modes including: driving, steering, jumping and zero-radius turning. In driving and steering modes, the robot moves along straight and circular trajectories, respectively. The robot performs these motional modes using movable internal masses. In the jumping mode, it can jump over obstacles and in the zero-radius turning mode, the robot can turn with zero-radius to improve the motion flexibility. Furthermore, the attempts to establish the dynamic models of some motional modes are made and finally, the accuracy of the obtained dynamic models is verified by simulation and experimental results.

Design and Implementation of a Novel Spherical Mobile Robot

Two-step identification of non-linear manoeuvring models of marine vessels

The invention discloses a four-rotor aircraft fault-tolerant control method and belongs to the field of aerocraft control. According to the method, first, based on a mathematical model of an aircraft, an attitude model under the condition of system faults of the aircraft is established; then, according to the attitude model, an adaptive law of fault estimation of an aircraft system is brought out, and a transfer function of loss of actuator effectiveness of the aircraft is also established; an adaptive law of fault estimation of loss of actuator effectiveness is put forward based on the loss of actuator effectiveness; and at last, based on the fault estimation of the system and the fault estimation of loss of actuator effectiveness, a fault-tolerant controller of an aircraft attitude system is designed. Thus, fault-tolerant control of four-rotor aircrafts is realized. By means of the method, probability of air crashes of four-rotor aircrafts is remarkably reduced, and flying reliability and safety of aircrafts are improved.

Four-rotor aircraft fault-tolerant control method

In a health management system, prognostics, which is an engineering discipline that predicts a system’s future health, is an important aspect yet there is currently limited research in this field. In this paper, a hybrid approach for prognostics is proposed. The approach combines the least squares support vector regression (LSSVR) with the hidden Markov model (HMM). Features extracted from sensor signals are used to train HMMs, which represent different health levels. A LSSVR algorithm is used to predict the feature trends. The LSSVR training and prediction algorithms are modified by adding new data and deleting old data and the probabilities of the predicted features for each HMM are calculated based on forward or backward algorithms. Based on these probabilities, one can determine a system’s future health state and estimate the remaining useful life (RUL). To evaluate the proposed approach, a test was carried out using bearing vibration signals. Simulation results show that the LSSVR/HMM approach can forecast faults long before they occur and can predict the RUL. Therefore, the LSSVR/HMM approach is very promising in the field of prognostics.

https://www.mdpi.com/1424-8220/13/5/5542/pdf

A Hybrid LSSVR/HMM-Based Prognostic Approach

Spherical robot is a special kind of nonholonomic system that cannot be converted to chained form, which means most of the well-known control methodologies are not suitable for this system. For the trajectory tracking of BHQ-1, a spherical robot designed by our lab, a two-state trajectory tracking controller is proposed in this paper. First, the kinematic model of the robot is built using screw theory and exponential method and the controllability is proved based on the differential geometric control theory. Then to solve the two-state trajectory tracking problem of BHQ-1, a shunting model of neurodynamics and Lyapunov's direct method are combined to design a two-state trajectory tracking controller, of which the Lyapunov stability is validated. Finally, typical simulation examples, such as tracking linear, circular, and sinusoidal trajectories, are introduced to verify the effectiveness of the proposed controller. In this paper the proposed method can also be applied to the control of other spherical robots.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0263574711000518

Two-state trajectory tracking control of a spherical robot using neurodynamics

The invention provides a path deviation generation analysis method for a ship at sea, which comprises the following steps of: (1) inputting longitude and latitude coordinates Q (xq, yq and zq) of a place of a departure, longitude and latitude coordinates M (xm, ym and zm) of a destination; (2) computing an expected optimum path; (3) correcting the expected path in segments; (4) computing the deviation between the ship and the path section; (5) judging whether the ship is in the current path section; and (6) if so, repeating the step (4), otherwise conducting the calculation of the next path section, and repeating the step (4). The path obtained by the invention can realize more economic and safer sailing, is beneficial to navigation, brings great convenience for autopilot sailing only by increasing shorter sailing distance, is also beneficial to path control, and also improves the control precision of paths.

Path deviation generation analysis method for ship at sea

The invention provides a ship rudder/wing rudder-fin/wing fin combined control method. A course detection device and a rolling detection device respectively detect and transmit a ship course angle sigThe invention provides a ship rudder/wing rudder-fin/wing fin combined control method. A course detection device and a rolling detection device respectively detect and transmit a ship course angle signal and a rolling angle signal to an information processing unit; a course/rolling robust controller is adopted in the information processing unit according to the ship course angle signal and the rolnal and a rolling angle signal to an information processing unit; a course/rolling robust controller is adopted in the information processing unit according to the ship course angle signal and the rolling angle signal to calculate needed course strengthening torque and rolling strengthening torque, respectively calculate needed rudder angle, wing rudder angle, fin angle and wing fin angle by a rudling angle signal to calculate needed course strengthening torque and rolling strengthening torque, respectively calculate needed rudder angle, wing rudder angle, fin angle and wing fin angle by a rudder angle/wing rudder angle distributor and a rudder angle/wing rudder angle distributor according to the course strengthening torque and the rolling strengthening torque and use the rudder angle, theder angle/wing rudder angle distributor and a rudder angle/wing rudder angle distributor according to the course strengthening torque and the rolling strengthening torque and use the rudder angle, thewing rudder angle, the fin angle and the wing fin angle as the output of the information processing unit; a rudder servo system, a wing rudder servo system, a fin servo system and a wing fin servo sy wing rudder angle, the fin angle and the wing fin angle as the output of the information processing unit; a rudder servo system, a wing rudder servo system, a fin servo system and a wing fin servo system respectively accept a rudder angle demand signal, a wing rudder angle demand signal, a fin angle demand signal and a wing fin angle demand signal to drive a rudder, a wing rudder, fins and wing fstem respectively accept a rudder angle demand signal, a wing rudder angle demand signal, a fin angle demand signal and a wing fin angle demand signal to drive a rudder, a wing rudder, fins and wing fins and effectively control the course and the rolling of a ship. The invention can improve the course control effect and the rolling stabilization effect of the ship.ins and effectively control the course and the rolling of a ship. The invention can improve the course control effect and the rolling stabilization effect of the ship.

Ship rudder/wing rudder-fin/wing fin combined control method

The invention provides a ship course intelligent coordination control method which comprises the steps of: 1, setting an expected course angle; 2, calculating a deviation of a real course angle and the expected course angle; 3, obtaining a tilt control command signal; 4, calculating a course angle really output by a ship; 5, identifying a ship motion inverse system model, regulating parameters of a least square support vector machine; and 6, repeating the calculation of the step 2. By adopting a ship course compounding control measure combining inverse control with fuzzy control, the invention effectively overcomes the defect of inverse control caused by inaccurate identification of the inverse model based on input and output data, establishes a ship control inverse system model by adopting the least square support vector machine, has the advantages of simple structure design and high steady state accuracy, and can realize accurate control of course holding by combining with the advantages of rapid response, strong anti-interference capability and good robustness of the fuzzy control.

Ship course intelligent coordination control method

The invention provides an intelligent stepping fault-tolerance control method comprising the following steps of: (1) establishing a database of a robust fault-tolerance controller of a failure working condition; (2) dispatching and running a normal-operation working condition controller; (3) circularly checking and judging whether a signal exceeds a threshold value; (4) dispatching and running a passive-operation robust fault-tolerance controller; (5) diagnosing specific failure information of a system; (6) switching to a reconstructing fault-tolerance controller; and (7) repeating the step (3). The invention adopts the intelligent stepping fault-tolerance control method, organically combines robust passive fault-tolerance control with high real-time performance and poor performance and active fault-tolerance control with good performance and poor real-time performance, sufficiently exerts respective advantages, carries out the intelligent stepping fault-tolerance control of the system and reduces the real-time processing requirements and the difficulty of a system failure checking unit. Compared with the single passive and active fault-tolerance design, the invention has the advantages of simple structure, strong reliability, good real-time performance, strong universality, and the like and completely satisfies the requirements of engineering design.

Intelligent stepping fault-tolerance control method

The invention provides a multifunctional control device of a small waterline plane ship hydrofoil and column rudder, comprising two hydrofoils and a column rudder mechanism; each hydrofoil and the column rudder mechanism comprise hydrofoils; a hydrofoil strut fixed on the hydrofoil, two wing flaps symmetrically distributed on the hydrofoil and at the both sides of the hydrofoil strut and a columnrudder arranged on the hydrofoil strut; two hydrofoils and the column rudder mechanism are respectively installed at the front part and the rear part of a small waterplane area twin-hull ship; two sheet bodies of the hydrofoil and the small waterplane area twin-hull ship are fixedly connected according to a certain installation angle; the hydrofoil strut is fixedly connected with a connection body at the upper part of the small waterplane area twin-hull ship. The multifunctional control device of the invention has multiple functions, can shorten transient time from hullborne operation to foilborne operation, weaken heave motion and pitching motion of the small waterplane area twin-hull ship, weaken rolling motion of the catamaran, control inclination angle of the ship, has course control function, can effectively shorten steering gyration radius, and improve the safety, navigability and maneuverability of the small waterplane area twin-hull ship.

Gaoyun Li

Papers

Path deviation generation analysis method for ship at sea

Ship rudder/wing rudder-fin/wing fin combined control method

Ship course intelligent coordination control method

Intelligent stepping fault-tolerance control method

Multifunctional control device of small waterline plane ship hydrofoil and column rudder