四足步行机跨沟前后的步态分析

本文针对四足步行机在直线行走时的跨沟步态进行了讨论.首先对步行机跨沟前周期步态的运动特性运用相位的概念作了阐述.在此基础上,分别对步行机的最大越沟能力的确定.越沟前初始位置的选取,姿态调整步态的规划和优化,以及稳定性的判别等问题作了分析和研究.并提出了解决此类问题的设想.最后,从简便、通用的角度制订了一套简易实用的跟随越沟步态,为四足步行机越为步态的实现提供了依据.     

Near-optimal gait generations of a two-legged robot on rough terrains using soft computing

A two-legged robot will have to generate its near-optimal gaits after ensuring maximum dynamic balance margin and minimum power consumption, while moving on the rough terrains containing some staircases and sloping surfaces. Moreover, the changes of joint torques should lie below a pre-specified small value to ensure its smooth walking. The balance of the robot and its power consumption are also dependent on hip trajectory and position of the masses on various limbs. Both neural network- and fuzzy logic-based gait planners have been developed for the same, the training of which are provided using a genetic algorithm off-line. Once optimized, the planners are found to generate optimal gaits of the two-legged robot successfully for the test cases.     

Co-simulation research of a novel exoskeleton-human robot system on humanoid gaits with fuzzy-PID/PID algorithms

Legged exoskeletons supplement human intelligence with the strength and endurance of a pair of wearable mechanical legs that support heavy loads. The exoskeleton-type system is a nonlinear system with uncertainty of parameters, which is not easy to be identified with traditional mathematical model. This paper presents co-simulations of a novel exoskeleton-human robot system on humanoid gaits with fuzzy-PID/PID algorithms, which do not need the precise model. The lower extremity exoskeleton model with series–parallel topology was briefly described and the gait characteristics were analyzed. The co-simulation method integrates ADAMS and MATLAB/SIMULINK with fuzzy-PID/PID algorithms, which were used to develop the control schematic of the exoskeleton-human robot system. Finally, co-simulations of humanoid gaits and movements, which include level walking, stair ascent, stair descent, side kick, squatting down and standing up, were provided to confirm the performances and effectiveness of the proposed control approach.     

An aperiodic straight motion planning method for a quadruped walking robot

In even terrain, wave gait is the periodic gait having the optimal stability. In this paper, we focus on aperiodic forward straight motion having the lifting sequence of wave gait in order for quadruped to adapt to terrain and to have good moving capability. We investigated the condition of support pattern from which such gait motion can be generated. It is proved that from any support pattern satisfying the condition, it is always possible to transform the given support pattern to the support pattern of wave gait. An aperiodic gait planning method that adapt to terrain and maximize moving capability is proposed. A simulation result shows that the proposed method works well in rough terrain having forbidden areas.     

Optimal Trajectories for a Quadruped Robot with Trot,Amble and Curvet Gaits for Two Energetic Criteria

In this paper, optimal cyclic reference trajectories aredesigned for three gaits of a quadruped robot, the curvet, theamble, and the trot, taking into account the actuatorscharacteristics. The gaits are composed of stance phases andinstantaneous double supports. The principle of virtual leg isused to obtain simpler dynamic model describing the motion ofthe quadruped. The impact phases are modeled by passive impactequations. For the curvet the step is composed of twodifferent half steps. For the amble and trot gaits twofollowing half steps are symmetrical.The optimization problem is solved with an algebraicoptimization technique. The actuated joint evolution is chosenas a polynomial function of time. The coefficients of thepolynomial functions are optimization parameters. Thequadruped studied has non-actuated ankles. The kineticmomentum theorem permits to define the evolution of this non-actuated variable in function of the actuated variables. Twoenergetic criteria are defined: a torque cost and an energetic cost. The first is represented by the integral of the torquenorm and the second by the absolute value integral of theexternal forces work. The two criteria are calculated for adisplacement of one meter. During the optimization process,the constraints on the ground reactions, on the validity ofimpact, on the torques, on the joints velocities and on themotion velocity of the robot prototype are taken into account.Simulation results are presented for the three gaits. Allmotions are realistic. Curvet is the less efficient gait withrespect to the criteria studied. For slow motion, trot is themore efficient gait. But amble permits the fastest motion withthe same actuators.     

蛇形机器人研究现况与进展

仿生技术与机器人技术的结合，使机器人从结构设计到运动模式的选择都有了 新的进展，这大大扩大了机器人的应用领域．本文阐述了仿蛇形机器人的应用背景和研究现 状，并展望了其未来的发展．     

Soft computing-based expert systems to predict energy consumption and stability margin in turning gaits of six-legged robots

Turning gaits are the most general and very important ones for omni-directional walking of a six-legged robot. Soft computing-based expert systems have been developed in the present work to predict specific energy consumption and stability margin of turning gait of a six-legged robot. Besides back-propagation neural network, three approaches based on adaptive neuro-fuzzy inference system have been developed and their performances are compared with each other. Genetic algorithm-tuned multiple adaptive neuro-fuzzy inference systems are found to perform better than other approaches. This could be due to a more exhaustive search conducted by the genetic algorithm in place of back-propagation algorithm and the use of two separate adaptive neuro-fuzzy inference systems for two different outputs.     

Path tracking with quadruped walking machines using discontinuous gaits

Discontinuous gaits for walking machines offer great advantages over wave gaits, and they seem more adequate for following a path over irregular terrain. This paper, focused on quadruped walking robots, addresses the problem of following an arbitrary path using both discontinuous crab and turning gaits. First, the paper presents the algorithms to generate these gaits as local motions and highlights their advantages in comparison with continuous gaits. This comparison considers stability, velocity, power consumption and terrain adaptability. The algorithms for tracking an arbitrary trajectory using these gaits are then introduced, and some simulations and experimental results are reported.     

面向蛇形机器人的三维步态控制的层次化联结中枢模式生成器模型

提高蛇形机器人的三维运动控制能力是提高蛇形机器人环境适应能力的关键之一. 虽然联结中枢模式生成器(Connectionist central pattern generator, CCPG)模型具有复杂度小、适合硬件实现等优点, 但是目前的CCPG模型难以生成相位协调的多自由度运动的控制信号,从而限制了它的三维步态控制能力. 本文根据生物CPG机制的分层结构和运动神经元的功能,提出一个有层次化结构的CCPG (Hierarchical CCPG, HCCPG)模型. HCCPG模型由基本节律信号生成层、模式形成层、运动信号调整层这三个部分组成. 运动信号调整层的运动神经元能够独立地对模式形成层的输出信号的幅值、相位等进行调整,从而较好地 解决了CCPG模型难以生成相位协调的多自由度运动控制信号的问题. HCCPG模型具有步态控制能力强、复杂度小、有良好的扩展性等优点,从而适合用于控制三维步态. 在HCCPG模型的基础上提出一个三维步态控制方法.仿真验证了这个控制方法的有效性.     

Gait definition and successive gait-transition method based on energy consumption for a quadruped

In nature,to realize the smooth motion for different speeds,the continuous gait transition is usually required for the quadrupeds.Thus,the gait simulation of quadrupeds is a requisite step to obtain the stable and energy-efficient gait for the walking machines.In this paper,the definitions of the two gait parameters,phasic difference and duty factor are presented,which can determine the gait of the quadrupeds.Then,several typical gaits of the quadrupeds are analyzed such that the seven standard gaits and corresponding parameters are summarized.Additionally,the variance law of the two parameters,which determine the relationship of gait transition,is analyzed.Furthermore,the quadruped gait derivative spectrum (QGDS) is proposed and the gait definition of the quadrupeds is presented.To minimize the power consumption,the choice criterion of gait,the optimal gait in terms of the motion speed,duty factory,and power consumption for the walking machines,is developed.Last,the continuous variance of the gait is implemented by the simulation of the gait transition from walk to trot,which evaluate the choice criterion and transition of gait.