Advanced Materials Research Vols. 308-310

Abstract: In order to realize accurate rotation of steel pipe in automatic rolling pipe bender, a tilt cylinder six bar mechanism driven by pneumatic cylinder was presented. Based on the analysis of mechanism motion’s state, the motion process was divided into three working stages: clamping, rotating and loosening back. And kinematics parameters in every phase of the mechanism were obtained by complex number vector method, furthermore the mechanism kinematics characteristics of the whole process were gained. The results of the simulation example indicated that the mechanism has less change in velocity and more smooth motion during clamping and rotating stages.

Abstract: In order to meet the demands for dextrous robotic limbs in such fields as the dangerous rescue, the disabled people assistance, and the industrial production line, we carry out the research about a robot upper limb which is composed of 6 DOFs and has the ability of finishing complex movements instead of a real upper limb. A virtual prototype of the robot upper limb is designed for analyzing the system comprehensively, and an optimal pneumatic balance design is studied for the sake of decreasing the output torque and the dimensions of the robot upper limb. Meanwhile, simulation experiments for the limb with pneumatic balance design and without pneumatic balance design have been finished, and the results showed that the performance of the limb with pneumatic balance design is better.

Abstract: This paper develops an approach to overcome the misjudgment and omission problems of determining interference for parallel cable-driven robots, which is essential to clear interference classification in the first place. According to the clear classification, interference condition between a cable and a cable or a cable and an edge of the end-effector has been derived according to all kinds of position relations between the feet of the common perpendicular; the on a cable with a plane of the end-effector has been proved. Compared with the existing approaches, the proposed method can determine the interference region more reasonably.

Abstract: The contact characteristics of spherical gear and ring-rack are researched in this paper. First, the tooth profile surface equation of spherical gear is established on the basis of the transmission theory of spherical gears. After that, the profile surface equation of ring-rack is established. Then, kinematics of the transmission of spherical gear and ring-rack is researched, the appreciate coordinates are established, and the profile surfaces of spherical gear and ring-rack are described in the same coordinate. Then, the contact analysis is conducted between spherical gear and ring-rack, and the contact point and ellipse parameters are acquired, as well as the rules of their evolvements. The conclusions above are benefit to further research on the transmission of spherical gear and ring-rack.

Abstract: For the general parallel mechanisms(PMS), since the coupling between kinematic chains, the nonlinear relation between the input and output is presented, which have led to difficulty in the trajectory planning and precision control. Design of motion decoupled parallel mechanisms(DPMS) has become a good new topic in this area and has captured researcher's attention. In this work, the approach to a synthesis of three degree-of-freedom(3-DOF) DPMS is considered based on screw theory and motion synthesis ideas. Criterions for type synthesis of the branches for DPMS is established according to the twist screw system of the limbs, which assures the decoupling in each limb. Then a six-step procedure is presented for the type synthesis of 2T1R decoupled mechanisms.

Abstract: In order to demonstrate the validity and the benefit of the closed-chain kinematics of four-link motional method for the gait of wall-climbing caterpillar robot, the mathematical model and the relation of kinematical parameters were built. The caterpillar robot can climb on vertical wall by coordinated rotation of one active joint and three passive joints. To testify the availability of the closed-chain kinematics of four-link method, a prototype of wall-climbing caterpillar robot with three kinds of adhesion modules was designed. A successful wall-climbing experiment confirms the principles of the closed-chain kinematics. The results show that the basis for selecting driving joints was reasonable and that the adhesion module can produce powerful adsorption force with small weight and volume to ensure the safety and reliability of wall-climbing.

Abstract: Based on the control decoupled principle and approach of Position and Orientation Characteristic (in short, POC) set, a novel decoupled parallel robot with 3-Translation and 2-Rotation (in short, 3T2R) outputs has been presented in the paper. And the topological structure of this new mechanism is fully decoupled, which have the advantages of easily control, simple kinematic analysis, and so on. Then the structure and displacement analysis of this novel parallel robot have been accomplished. The research provides theoretical basis for design and practical applicability of this novel parallel robot.

Abstract: In order to overcome the deficiencies of outdated hydraulic system of drilling rig, The testing drilling system is designed, which provides drilling parameters of inspecting, recording and controlling to meet the need of high power and complex drilling controlling. Meanwhile, the improved incremental PID and the multiple algorithm of Fuzzy-PID realize closed-loop feedback control of drilling pressure and rotary speed, what enhance the control system stability and accuracy, and achieve the sake of good control effect so that the system achieves the targets with speed range from 0 to 160r/min and pressure range from 0 to 20MPa.

Abstract: A 7-DOF upper limb kinematical model is built based on Rigid Body Assumption method. A protocol is proposed to measurement and analysis the motion of upper limb using the optical capturing system and a new refined spatial kinematical Parameters algorithm. 13 basic actions of Activity of daily life (ADL) are studied based on the kinematical model and protocol.

Abstract: High-property carbon refractories for blast furnaces should have high thermal conductivity and excellent porosity characteristics. The relationship between porosity characteristics and thermal conductivity of different graphite size (100mesh, 200mesh, 325mesh, 600mesh and 100mesh respectively) containing carbon refractories was investigated by using mercury porosimeter and laser thermal conductivity instrument. The results indicate that the thermal conductivity was reduced with the increase of porosity and <0.1μm pore volume as well as the decrease of mean pore diameter under the same condition, which was related to the short of thermal conductive route.