Applied Mechanics and Materials Vols. 321-324

Abstract: The small-signal stability problem of complex connected DC DPS was studied. Using mathematical induction method, it is proved that the N subsystems cascaded DPS can be seemed as two equivalent subsystems at arbitrary interface as the stability conclusion is the same. But for complex connected DPS which have M sources, it could be equivalent to M sources and one load system instead of two equivalent subsystems and M minor loop gain at M different interfaces should be satisfied Nyquist criterion simultaneously to ensure the DPS's stability.

Abstract: A 6-UPS parallel is adopted to complete mating surfaces grinding of the cervical implant prosthesis instead of the manual surgical instruments in robot-assisted surgery cervical disc replacement system. Therefore, the surgical assistant parallel robot end-effector has better flexibility in some continuous space and best movement and force transmission performance on the moving trajectory beyond reasonable structures and enough degrees of freedom of the grinding movement. In this paper, the dexterity of the surgical assistant 6-UPS parallel robot is analyzed. Firstly, the vector construction method is used to solve Jacobian matrix of the surgical assistant 6-UPS parallel robot, and then the linear velocity and angular velocity dexterity indicators are used to analyze the dexterity of the surgical assistant parallel robot. From the results, the parallel robot movement and force transmission performance degrades away from the surgical space and the cervical vertebra grinding parallel robot has best grinding performance near the center surgical workspace of the moving platform.

Abstract: The direct-drive servo motor is servo product with high performance widely applied in the fields of robotics and manufacturing due to its special construction and high-precision design. Considering the working principles of laser engraving machines, as well as the impact on the dynamic and static performance of the control system exerted by PID controllers frequently integral correction link in the process of start and stop, this article describes in detail how to achieve accurate positioning of direct drive servo motor by adjusting PID parameters. Key Words Servo motor,PID variable structure,Servo positioning,Laser engraving machine

Abstract: As the detection efficiency and defect evaluation accuracy of traditional ultrasonic testing of weld is low, in this paper a new control system is developed to accomplish high-efficiency and high-precision evaluation of weld. This system includes Centralized Control, Control of ultrasonic probe and running mechanism. The heart of the system is DSP, and it can control motion of the scan robot along the circular rail and ultrasonic probe along radial direction of circumferential weld, and realize collection and processing of ultrasonic signal by the comprehensive application of computer, automation, precision instrument, motor driver technology. Practice shows that this new system has realized digital, intelligent, automation of ultrasonic weld inspection, and improved Reliability and efficiency of weld inspection.

Abstract: A new nonlinear PID control method is proposed to meet the needs of a vertical robot running under a high speed condition, whose joint transfer function changed with the joints position. Firstly, the experimental system has been set up. Then the joints transfer functions can be established. Moreover, the relationship between the PID parameters and joints angle position θ has been set up by the least square method. So the nonlinear PID controller can be obtained. In the end, several testing experiments have been caught out. The result shows that the nonlinear PID controllers have fast respond, which can meet the satisfaction of the robot under a high speed condition.

Abstract: According to mine hydraulic testing requirement, the article puts forward an online hydraulic testing method, which is used in mine hydraulic cylinder,three-way valve and so on. It makes real-time, multi-channel hydraulic pressure signal gathering and processing procedure come true, thus completes the online assessment for mine hydraulic testing. The method uses a multi-thread, multi-channel, multi-buffer synchronous detection mode by combining soft and hardware hydraulic test features and establishes data collecting and interactive model as well as data display and storage model, which owns a powerful interactive interface. It can display real-time multi-channel pressure histogram and waveform graph, which also has function of personalized settings, real-time detection, permanent preservation, history record inquiry and report print. Furthermore, this mechod reflects the real-timing and reliability of system in practical application.

Abstract: In teleoperation tasks, communication delays between master and slave sides negatively affect the stability and transparency of closed loop system, and make it difficult to maintain a desired contact force. In order to improve the performance of contact force control in teleoperation under large time delays, a shared compliant control method is proposed in this paper. On the master side, the operator issues a desired contact force command according to the feedback of the contact stiffness identified on line besides motion commands. And on the slave side, a local contact force controller is designed using an adaptive Smith predictor, so as to shares control load with the operator. Experimental results show that this method can improve the force control performance, lower the difficulty of operation, and help the operator complete contact tasks with proper forces.In teleoperation tasks, communication delays between master and slave sides negatively affect the stability and transparency of closed loop system, and make it difficult to maintain a desired contact force. In order to improve the performance of contact force control in teleoperation under large time delays, a shared compliant control method is proposed in this paper. On the master side, the operator issues a desired contact force command according to the feedback of the contact stiffness identified on line besides motion commands. And on the slave side, a local contact force controller is designed using an adaptive Smith predictor, so as to shares control load with the operator. Experimental results show that this method can improve the force control performance, lower the difficulty of operation, and help the operator complete contact tasks with proper forces.

Abstract: This paper sets out to given a geometric method for solving three-arm five degrees of freedom manipulator kinematics inverse problem. With the both eyes stereo-identity system, the bomb-disposed robot accomplished the EOD mission in a completely open environment. using image recognition technology, estimation about producing weight and clamping width in the image of the suspicious explosive object is obtained. The project is proved feasible by experiment.

Abstract: Mobile robot becomes more and more perfect with people research continuously, obstacle avoidance is one of the most basic function in the process of operation. At present, the robot simulation system is an important tool of researching robot. In this paper, hardware design and software design were done by NSTRSS and real-time dynamic obstacle avoidance simulation of mobile robot is completed successfully. The experimental result shows that the simulation has 3D scene, lively effect and a good operation interface.

Abstract: Error of stereovision reconstruction comes from feature extraction, correspondence and calibration. This paper is focused on investigation of the relation between reconstruction accuracy and calibration accuracy of a stereovision. A model of stereovision system is established, which consists of two cameras configured with their coordinate not paralleled. An array of points in the common view field of the two cameras is projected onto the image planes of the left and right cameras respectively and forms the left image and right image. After changing the calibration parameters of the stereovision system, including intrinsic parameters of the cameras and their relative position and pose, the array of points are reconstructed and compared with their original positions. The main factors affecting the reconstruction errors are discussed.