Dynamic simulation and experimental study of inspection robot for high-voltage transmission-line

A mobile robot developed by Wuhan University for full-path hotline inspection on 220 kV transmission lines was presented. With 4 rotating joints and 2 translational ones, such robot is capable of traveling along nonobstacle straight-line segment and surmounting straight-line segment obstacles as well as transferring between two spans automatically. Lagrange＇s equations were utilized to derive dynamic equations of all the links, including items of inertia, coupling inertia, Coriolis acceleration, centripetal acceleration and gravity. And a dynamic response experiment on elemental motions of robot prototype＇s travelling along non-obstacle straight-line segment and surmounting obstacles was performed on 220 kV 1 ： 1 simulative overhanging transmission-line in laboratory. In addition, dynamic numerical simulation was conducted in the corresponding condition. Comparison and analysis on results of experiment and numerical simulation have validated theoretical model and simulation resolution. Therefore, the dynamic model formed hereunder can be used for the study of robot control.     

Mechanics analysis of a wheelchair robot with wheel-track coupling mechanism

A barrier-free wheelchair robot with a mechanism coupled by wheel and track is presented in this paper. Using the wheelchair,the lower limb disabled persons could be more relaxed to take part in outdoor activities whether on flat ground or stairs and obstacles in the city. The wheel-track coupling mechanism is designed and the stability of the bodywork of the wheelchair robot on the stairs is analyzed. In order to obtain the stability of wheelchair robot when it climbs obstacles,centroid projection method is applied to analyze the static stability,stability margin is proposed to provide the stability under some dynamic forces,and the push rod rotation angle in terms of the guaranteed stability margin is given. Finally,the dynamic model of the wheelchair robot based on Lagrange equation is established,which can be a theoretical foundation for the wheelchair control system design.     

Simulation Platform of Underwater Quadruped Walking Robot Based on MotionGenesis Kane 5.3 and Central Pattern Generator

It will still in lack of a simulation platform used to learn the walking of underwater quadruped walking robot. In order to alleviate this shortage,a simulation platform for the underwater quadruped walking robot based on Kane dynamic model and CPG-based controller is constructed. The Kane dynamic model of the underwater quadruped walking robot is processed with a commercial package MotionGenesis Kane 5. 3. The forces between the feet and ground are represented as a spring and damper. The relation between coefficients of spring and damper and stability of underwater quadruped walking robot in the stationary state is studied. The CPG-based controller consisted of Central Pattern Generator（ CPG） and PD controller is presented,which can be used to control walking of the underwater quadruped walking robot. The relation between CPG parameters and walking speed of underwater quadruped walking robot is investigated. The relation between coefficients of spring and damper and walking speed of underwater quadruped walking robot is studied. The results show that the simulation platform can imitate the stable walking of the underwater quadruped walking robot.     

Stable walking of quadruped robot on unknown rough terrain

Quadruped robot is considered to be the most practical locomotion machine to negotiate uneven terrain, and shows superb stability during static walking. To improve the ability to go over rough terrain, this paper is focused on the stable walking and balance control of quadruped robots. 24 kinds of walking gaits are analyzed in order to derive the most stable and smoothest walking gait. Considering the inefficiency to model a terrain by its specified appearance, a uniform terrain model is established and by means of kinematic analysis, a method to adjust the body posture and center of gravity (COG) height is presented. Simulations demonstrate the effectiveness of the proposed method and the improvement of the adaptation of quadruped robots on rough terrain.     

Kinematics analysis for obstacle-surmounting capability of a joint double-tracked robot

A double-tracked robot is designed from mechanical and control perspectives, which consists of two segments connected with a swing joint. As the angle between the two segments of the robot platform can be changed, the robot can move like a four-tracked robot on many terrains. The center of gravity (CG) kinematics model is established, which plays an important role in the process of traveling over obstacles and climbing up stairs. Using this model, the CG change situation and the maximal height of the climbable obstacle are obtained. Then the relationship between the robot pitch angle and the height of the obstacle is established. Finally, a reasonable system structure for the robot is designed and its kinematics analysis for obstacle-surmounting capability is conducted through experiments.     

Dynamic modeling and simulation for nonholonomic welding mobile robot

Based on the Newton-Euler method, the dynamic behaviors of the left and right driving wheels and the robot body for the welding mobile robot were derived. In order to realize the combination control of body turning and slider adjustment, the dynamic behaviors of sliders were also investigated. As a result, a systematic and complete dynamic model for the welding mobile robot was constructed. In order to verify the effectiveness of the above model, a sliding mode tracking control method was proposed and simulated, the lateral error stabilizes between ?0.2 mm and 0.2 mm, and the total distance of travel for the slider is consistently within ±2 mm. The simulation results verify the effectiveness of the established dynamic model and also show that the seam tracking controller based on the dynamic model has excellent performance in terms of stability and robustness. Furthermore, the model is found to be very suitable for practical applications of the welding mobile robot.     

Walking Stability Control Method for Biped Robot on Uneven Ground Based on Deep Q-Network

A gait control method for a biped robot based on the deep Q-network (DQN) algorithm is proposed to enhance the stability of walking on uneven ground. This control strategy is an intelligent learning method of posture adjustment. A robot is taken as an agent and trained to walk steadily on an uneven surface with obstacles, using a simple reward function based on forward progress. The reward-punishment (RP) mechanism of the DQN algorithm is established after obtaining the offline gait which was generated in advance foot trajectory planning. Instead of implementing a complex dynamic model, the proposed method enables the biped robot to learn to adjust its posture on the uneven ground and ensures walking stability. The performance and effectiveness of the proposed algorithm was validated in the V-REP simulation environment. The results demonstrate that the biped robot''s lateral tile angle is less than 3° after implementing the proposed method and the walking stability is obviously improved.     

Resonance Suppression Strategy for Humanoid Robot Arm

To address the problem of resonance in the control of a robot arm, a resonance suppression strategy is proposed for a single-joint humanoid robot arm based on the proportional-resonant(PR) controller. First, an arm joint model of the humanoid robot is established. Then the influence of resonance frequency on the performance of the control system with the robot arm is analyzed. The voltage fluctuation of the drive motor caused by the changes in arm motion is recognized as the disturbance of the current loop. The PR controller has the characteristic of disturbance rejection at a specific frequency. The output fluctuation of the driving system caused by the change of arm motion state at the resonance frequency is suppressed. Therefore the output current of the inverter will not be affected by the vibration of the arm at the resonance frequency. Finally, the control system is verified by MATLAB/Simulink simulation. The simulation results demonstrate that the control strategy for the humanoid robot arm based on the PR controller can suppress the resonance of the arm effectively, improving the dynamic performance and system stability.     

Motion Planning of Humanoid Robot for Obstacle Negotiation

The motion planning for obstacle negotiation by humanoid robot BHR-2 through stepping over or stepping on/off the wide and flat obstacle at known locations is presented. In the trajectory generation method,first the constraints of the foot motion parameters which include obstacle dimensions and the distance of obstacle from the humanoid robot is formulated. By varying the values of the constraint parameters,different types of foot motion for different obstacles can be produced. In this method,first the foot trajectory is generated,and then the waist trajectory is computed by using cubic spline interpolation without first calculating the zero moment point (ZMP) trajectory. The dynamic stability during the execution of stepping over and stepping on/off trajectories are ensured by incorporating the ZMP criterion. The effectiveness of the proposed method is confirmed by simulations and experiments on humanoid robot BHR-2.     

Dynamic response to road roughness on a tractor-semitrailer system with driver body model

A linear mass-spring system model of a tractor-semitrailer together with driver body parts and sprung seat is presented. Natural frequencies of the system are calculated and response of components in the system to road roughness is completed by means of computer simulation and power spectral density (PSD) approach in all of road conditions and loading cases. The results show that the severest situation of response of the system occurs when the road in rough condition and vehicle unladen. The most sensitive frequency to human body parts is around 0.9 Hz, and model types of a human body seem to be not significant to the response of a heavy tractor-semitrailer system, including to the response of the driver himself.     

一种用于人体上肢爆发力测试的机器人研究

爆发力是速度力量的一种主要表现形式,是速度与力量的乘积.在大多数动力性体育项目中,爆发力比绝对力量有着更加重要的意义.因此,对爆发力的定量测试及对其机制的研究成为运动生物力学和人机接触交互研究中备受关注的课题.在分析机体爆发力生理学机制的基础上,根据人体上肢的运动特点,确定了可用于测试人体手臂运动爆发力的两关节测力机器人设计方案,分析了该机器人的测力原理,研究了机械手相应的力控制算法,并对人体爆发力的计算方法与评价标准进行了初步探讨.该测力机器人为人体上肢肌肉运动感觉和人机接触交互研究提供了一个系统的实验平台.     

乳化炸药溶胀过程的稳定性研究

文章通过测定乳化炸药的溶胀率及内相ＮＨ４ＮＯ３溶失率，分析对比了不同乳化剂对其稳定性的影响．根据界面科学的有关理论，提出了乳化炸药的溶解扩散渗透机理，指出乳化剂是影响其溶胀稳定性的关键因素，揭示了乳化炸药的溶胀性与其稳定性的关系，提供了选择乳化剂的理论依据．为判别乳化炸药的稳定性提供了一种新的方法．     

衰减转向盘冲击力矩的电动助力转向控制

针对汽车经过凸块或不平路面时导致转向盘上产生过大冲击力矩给驾驶员带来不适感的问题,通过建立电动助力转向动力学模型估计折算到转向小齿轮上的路面冲击力矩,最终确定出路面冲击补偿电流,用以衰减由路面冲击而产生的转向盘冲击力矩。实车试验结果表明,本文方法能够在不增加电动助力转向系统元件的基础上,有效衰减转向盘冲击力矩,有较好的实际应用价值。     

机械手动力学方程及优化设计

以机械手抓取物体为分析对象，以动力学Ｋａｎｅ方程为基础，建立机械手的动力学数学模型，导出机械人系统动力学方程，并提出机器人系统优化设计的一般方法。这种方法便于编程计算，算法简洁，对机器人的精密设计计算具有普遍适用意义。     

模拟爆炸地震波及其对框架结构的影响

基于能够描述爆炸地震波的非平稳随机过程模型进行爆炸地震波的模拟研究,给出能够考虑装药量和爆心距影响的单点爆炸地震波实用模拟方法。以15层框架结构为例,运用有限元分析软件建立空间板梁结构的有限元模型,计算结构的固有频率和固有振型,分析高层框架结构在模拟爆炸地震波作用下的动力响应。根据结构动力响应结果,判断结构的薄弱层,为工程抗震设计提供参考依据。     

动压作用下乳化炸药析晶现象的实验研究

为了研究敏化方式和乳化剂的含量对乳化炸药析晶现象的影响,利用水溶法测量了乳化炸药在动压作用下析晶量,用析晶量的大小来表征乳化炸药的抗动压性能,对提高乳化炸药的抗动压性能起到重要的指导作用。实验结果表明,在相同的动压作用下,玻璃微球敏化的乳化炸药的析晶量小于膨胀珍珠岩敏化的乳化炸药;随着乳化剂含量从3%增加到4%时,乳化炸药的析晶量减小。因此,采用玻璃微球做敏化剂及适当提高乳化剂的含量可以提高乳化炸药的抗动压性能。     

钢筋混凝土板在爆炸荷载作用下的破坏模式分析

目的更精确的界定和证明钢筋混凝土板在不同峰值压力、不同作用时间的爆炸荷载作用下发生的破坏模式变化的规律．方法采用有限元软件Abaqus对钢筋混凝土板的破坏模式进行分析，并考虑了钢筋混凝土的应变率效应．结果Abaqus的数值模拟结果显示，钢筋混凝土板在4种不同峰值压力、不同作用时间的爆炸荷载作用下会发生弯曲和剪切两种不同的破坏模式．结论钢筋混凝土板在相同强度的脉冲压力作用下会发生不同的破坏模式，随着峰值压力的增加与作用时间的减小，破坏模式逐渐由弯曲破坏转变为剪切破坏．爆炸峰值压力较小，作用时间较长时钢筋混凝土板主要发生板边缘和板中部的弯曲破坏：而在爆炸峰值压力较大，作用时间较短时主要发生支撑处的剪切破坏．     

Numerical analysis of tunnel reinforcing influences on failure process of surrounding rock under explosive stress waves

Based on mesoscopic damage mechanics, numerical code RFPA2D （dynamic edition） was developed to analyze the influence of tunnel reinforcing on failure process of surrounding rock under explosive stress waves. The results show that the propagation phenomenon of stress wave in the surrounding rock of tunnel and the failure process of surrounding rock under explosive stress waves are reproduced realistically by using numerical code RFPA2O; from the failure process of surrounding rock, the place at which surrounding rock fractures is transferred because of tunnel reinforcing, and the rockfall and collapse caused by failure of surrounding rock are restrained by tunnel reinforcing; furthermore, the absolute values of peak values of major principal stress, and the minimal principal stress and shear stress at center point of tunnel roof are reduced because of tunnel reinforcing, and the displacement at center point of runnel roof is reduced as well, consequently the stability of tunnel increases.     

丁二酰亚胺在乳化炸药体系中的乳化机理

从乳化剂对乳化炸药的稳定化作用、乳化剂在油相中的表面化学性质、乳化炸药连续相油膜的稳定性等几个方面探讨了乳化炸药体系的乳化机理．说明了聚异丁烯丁二酰亚胺乳化剂作为油相与水相的媒介与水相存在化学吸附,在界面处形成单分子油膜,构成坚韧、封闭的连续相油膜,对乳化炸药起着立体保护作用