Contents and Abstracts of Journal of Mechanical Engineering ISSN 0577-6686,CN 11-2187/TH

Cooperative Reconfiguration for a Reconfigurable Mobile Robot LIU Tonglin, WU Chengdong, LI Bin, LIU Jinguo （1. State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China; 2. Graduate School, Chinese Academy of Sciences, Beijing 100049, China; 3. School of Information Science ＆ Engineering, Northeast University, Shenyang 110004, China）Abstract： A main characteristic of the reconfigurable mobile robot AMOEBA-1 is that it has diverse configurations, but some reconfigurations are difficult to realize under the influence of ground conditions. A cooperative reconfiguration method is proposed to reduce reconfiguration resistance and enhance the adaptability of the robot to the environment. The mathematical model is established correspondingly. The kinematics and mechanical properties of each section of the robot are analyzed. A part of resistance is transformed into active force of reconfiguration, and transforms are actualized among five specific configurations. Further, the linearization of model based on a perturbation analysis method is used to reduce the computational complexity. Finally, an evaluation criterion is proposed for AMOEBA-I＇s cooperative reconfiguration performance. The validity of the cooperative reconfiguration method is proved by simulations and experiments.

Contents and Abstracts of Journal of Mechanical Engineering ISSN 0577-6686, CN 11-2187/TH

Research on Categorizing Innovation of Speed Reducers,Optimization Algorithm for Robotic Belt Surface Grinding Process,Design and Viscoelasticity Dynamics Modeling of Flexible Driven Unit for Robot＇s Joint

Contents and Abstracts of Journal of Mechanical Engineering ISSN 0577-6686,CN 11-2187/TH

Research on Environment Test Voltage Loading Method of Electrical Connector in Vacuum For problems that different voltage loading method of electrical connector produces different electric field, the calculation model and method of electric field are set up with the electrostatic field theory in view that the decrease or breakdown of insulation resistance and dielectric strength induced by surface fiashover cause failure of electrical connector in vacuum. Then in order to quickly and accurately evaluate the insulation life of electrical connector in vacuum environment, the optimized mathe- matical model of electric field is established nnder the condition of rated voltage by regarding the largest electric field and the most uniform electric field as objectives. Through extracting comprehensive evaluation function from the objectives by using signal-to-noise ratio of electric field, genetic algorithm is used to optimize the voltage loading method by converting multi objective to single objective. The optimal results show that the electric field not only increases about 50%, but also is more uniform, which provides the reference for the reliability evaluation of electrical connector in vacuum.

Contents of Journal of Mechanical Engineering ISSN 0577-6686,CN 11-2187/TH*

Vol. 47, No. 11, 2011 DOI: 10.3901/JME.2011.11.001 Linear Motion Control of Two-pendulums- driven Spherical Robot 1 ZHAO Bo WANG Pengfei SUN Lining LI Mantian (State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150080, China)

Contents and Abstracts of Journal of Mechanical Engineering ISSN 0577-6686,CN 11-2187/TH

Review on Key Technology of Hydrodynamic and Hydrostatic High-frequency Motor Spindles XIONG Wanli YANG Xuebing LV Lang YUAN Julong （National Research Center for High Efficiency Grinding, Hunan University, Changsha 410082, China） Abstract： High-speed spindles supported by hydrodynamic and hydrostatic hybrid bearings are widely applied in the field of high-speed precision machine tools due to highrotation accuracy, high dynamic stiffness, high vibration damping and long life. But some technical problems caused by integrated structure and high speed, including temperature rise control and motor performance optimization, are yet to be resolved when the integration of hybrid bearings and motor are developed to meet the requirements of ultra-high speed and ultra-precision machining Also major scientific problems involved in the dynamic and thermal characteristics of hybrid journal bearings and the mechanism of electromagnetic losses of high-frequency motor are to be further studied.

NO_3^-/NH_4^+ ratios affect plant growth, chlorophyll content,respiration rate, and morphological structure in Malus hupehensis seedlings

Malus hupehensis （Pamp.） Rehd. is a widely cultivated rootstock in China. We studied the effect of three NO3-/NH4＋ ratios （100/0, 50/50, and 0/100, molar basis） at total nitrogen （N） concentration of 8 mmoL L-1 in a nutrient solution on M. hupehensis seedlings. Plant biomass, NO3- and NH4＋concentrafion, chlorophyll con- tent, respiratory rate, and cellular structure were investi- gated. M. hupehensis seedlings at the NO3-/NH4＋ ratio of 50/50 had the highest level of fresh weight, dry weight, shoot length, and chlorophyll （a, b, and a ＋ b） content, but the lowest respiration rate in the leavesand roots. In addition, thickness and numbers of palisade and spongy tissue cells of the leaves were greater with this treatment than with other treatments. At the NO3-/NH4＋ ratio of 100/0, the leaves and roots had higher NO3- concentration and lower NH4＋ concentration. However, the opposite trend occurred at the NO3-/NH4＋ ratio of 0/100. Chloro- phyll （a, b, and a ＋ b） content was lowest at the NO3-/NH4＋ ratio of 100/0 than at the other ratios. At the NO3-/ NH4＋ ratio of 0/100, oxygen （02） consumption increased in the leaves and roots, and irregular epidermis and cortex cells were observed in the root apical meristematic and mature region. Our results indicated that the NO3-INH4＋ ratio at 50/50 was suitable for growth of M. hupehensis seedling to achieve the highest biomass production and efficiency.

Contents and Abstracts of Journal of Mechanical Engineering ISSN 0577-6686, CN 11-2187/TH

Effect of Kinematic Behavior of Caudal Fin on Fishlike Robot Propulsion during Steady Swimming CHEN Weishan XIA Dan LIU Junkao SHI Shengjun （State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150080, China）Abstract： The speed convergence algorithm is applied in the numerical simulation of a fishlike robot in self-propelled swimming. All simulations are started with the body at rest, the swimming speed is dynamically modified to converge to the steady value by verifying the fluid forces during the swimming process. The effects of kinematic behavior of caudal fin on fishlike robot propulsion are numerical investigated in the converged steady speed, while the propulsive mechanism and flow field structure are revealed. The results show that the steady speed can be predicted validly by using the speed convergence algorithm, while the relation between the kinematic behavior and the propulsion, power consumption and propulsive efficiency can be obtained through varying the phase difference and the maximum angle of attack. The effects of kinematic behavior of caudal fin on the wake structure and wake strength are clearly reflected in the three dimensional flow field structures. The fmdings are of great significance to the swimming speed prediction, effect of kinematic behavior on fishlike robot propulsion as well as the motion narameter design for fishlike robot

Contents and Abstracts of Journal of Mechanical Engineering ISSN 0577-6686,CN 11-2187/TH

Recent Research Advances and Expectation of Mechanical Engineering Science in China;Research Progress of Friction Behavior during Powder Forming;Review of Vehicle State Estimation Problem under Driving Situation;Fault Diagnosis Method Based on Acoustic Holography;Effect of Track Structure Parameters on Rolling Contact Stresses of Wheel-rail