Xiansheng Qin

Study on Reconfigurable CNC System

The aim of the study on the RCNC (Reconfigurable Computer Numerically Controlled) system is to provide a platform for the CNC development. The RCNC system is an open and reconfigurable system where a set of pre-defined components is given and an assembly of selected components is selected to satisfy the special customer requirements subject to the constraints. In this paper, the architecture of RCNC is proposed, and the software design of the system is discussed.

A combined feature extraction method for left-right hand motor imagery in BCI

The aim of BCI is to translate brain activity into a command for a computer. For this purpose, the EEG signal processing plays an important role, especially in feature extraction. In this paper, a combined feature extraction method is proposed for left-right hand motor imagery in BCI. The power in the sensorimotor rhythm band and the statistical features of wavelet coefficients are used for extracting features and support vector machine is adopted for pattern recognition of left-right hand motor imagery. The performance is tested by the EEG signals of subject b and subject g from the datasets1 BCI Competition IV. The results have shown the availability of this method. It provides a novel way to EEG feature extraction in BCI.

Motion Analysis and Control of a Single Leg of Hydraulically Actuated Quadruped Robots during Vertical Hopping

To address the requirements of high speed and mobility for quadruped robots under unstructured environments,a structure model of hydraulically actuated single leg is proposed.For vertical hopping,a two-phase kinematic model and a three-phase dynamic model of a single leg are established under the structure model.After that,the state analysis on the vertical hopping is conducted,and the inverse kinematics solution and the simulation of the hopping are also implemented for a single leg mass-center’s instant vertical hopping with 1.5 m/s.Then,the ground impact on the body structure,the operation characteristics and the output force of the hip joint and knee joint’s hydraulic cylinder,as well as the hydraulic system design during vertical hopping are discussed.Meanwhile,taking the periodicity of vertical hopping of a single leg into consideration,a PD(proportional-derivative) iterative learning control algorithm is applied to joint trajectory tracking,based on single leg’s dynamic model with hydraulic offset.The simulation results indicate that rapid and robust convergence is achieved in trajectory tracking using the presented model,which offers the design and control references for the succeeding prototype development.

Generalized-Disturbance Rejection Control for Vibration Suppression of Piezoelectric Laminated Flexible Structures

In the framework of disturbance rejection (DR) control, the paper proposes a generalized-disturbance rejection (GDR) control with proportional-integral (PI) observer for vibration suppression of smart structures under any unknown continuous disturbances. In the proposed GDR-PI control, a refined state space model is first constructed, and a generalized disturbance including the disturbance influence matrices, unknown physical disturbances, and state variables is defined. In the closed loop of GDR-PI control, physical disturbances can be counteracted indirectly by feeding back estimated generalized disturbances. By this means, the GDR-PI control remedies most of the defects in conventional DR control and has excellent performances especially in the following situations: (i) the disturbances are completely unknown; (ii) the number of sensor signals is less than the number of disturbances; (iii) the unknown disturbances vary fast. Finally, the GDR-PI control is validated and compared with state feedback control and conventional DR control available in the literature for vibration suppression of smart beams.

Design and Implementation of Multifunctional Automatic Drilling End Effector

In order to realize the automatic drilling in aircraft assembly, a drilling end effector is designed by integrating the pressure unit, drilling unit, measurement unit, control system and frame structure. In order to reduce the hole deviation, this paper proposes a vertical normal adjustment program based on 4 laser distance sensors. The actual normal direction of workpiece surface can be calculated through the sensors measurements, and then robot posture is adjusted to realize the hole deviation correction. A base detection method is proposed to detect and locate the hole automatically by using the camera and the reference hole. The experiment results show that the position accuracy of the system is less than 0.3mm, and the normal precision is less than 0.5°. The drilling end effector and robot can greatly improve the efficiency of the aircraft parts and assembly quality, and reduce the product development cycle.

Base Detection Research of Drilling Robot System by Using Visual Inspection

This paper expounds the principle and method of calibration and base detection by using the visual measurement system for detection and correction of installation error between workpiece and the robot drilling system. This includes the use of Cognex Insight 5403 high precision industrial camera, a light source, and the KEYENCE coaxial IL-300 laser displacement sensor. The three-base holes method and two-base holes method are proposed to analyze the transfer relation between the basic coordinate system of the actual hole drilling robot and the basic coordinate system of the theoretical hole drilling robot. The corresponding vision coordinates calibration and the base detection experiments are examined and the data indicate that the result of base detection is close to the correct value.

Research on the Motion System of the 6R Industrial Robot Based on the Look-Ahead Control

When the trajectory of the industrial robot was the complex space curve or surface, there would be lots of continuous short line segments through the commercial CAD/CAM software. In this case, the frequent acceleration and deceleration would occur for the traditional industrial robot when running the process. This was leading to the robot vibration, even damaging the components. Aiming at this problem, this article built the motion system based on look-ahead control. First, various constraints were summarized in running process. Then the program preprocess module calculated all information needed in look-ahead control in advance. Dangerous points were determined in accordance with judging criteria. And then the paper figured out the velocity of the connect points with constraint conditions and planned the acceleration and deceleration. At last, the velocity curve were converted to the final number of servo motor pulses by calling the modules of velocity interpolation, robot forward and reverse kinematics, coefficient transition and PID in turn, achieving the whole motion process.

Design and Experiment Study on a Quadruped Robot Single Leg with Composite Rigid-flexible Configuration for Gallop Gait

To address the requirements of high speed and mobility for quadruped robots galloping,a composite rigidflexible structure model is proposed for a single leg of quadruped robots.The composite rigid-flexible structure is designed for a single leg of quadruped robots,and operating characteristics with or without impact loading,stiffness characteristics,D-H kinematics and toe work space are analyzed.After that,taking noise factor such as ground impact under dynamic motion into consideration,linear quadratic Gaussian control is applied to driver control of a single leg of quadruped robots.Then,with vertical hopping as an important basic motion prototype for galloping,analysis and simulation of equal-height jumping control under disabled environment are conducted based on finite state machine and peak height feedback.Finally,continuous vertical hopping experiment of a single leg with composite rigid-flexible structure of quadruped robots is conducted.Analysis and experiment results indicate the rationality of the structure design and the effectiveness of the control scheme.

Flutter detection of composite plate using finite element and eigenvector orientation method

This paper examines the use of eigenvector orientation method to detect the onset of nonlinear supersonic flutter of composite plate modeled by finite elements. The accuracy of the eigenvector orientation method for prediction of the flutter boundary (indicated by a gradual loss of orthogonality between two eigenvectors) is demonstrated by using the example of a simply supported composite plate model at supersonic speed. It is proved that the eigenvector orientation method can avoid the modes coupling and be easily monitored.