Integrated design of legged mechatronic system

This paper presents a system based on the integrated design and experiment for a one degree-of-freedom (DOF) legged mechatronic system (LMTS). A six-bar linkage mechanism, which is derived from a four-bar linkage with a symmetrical coupler point and pantograph into one, is designed, and common controllers are used to control the velocity and position loops. For system-based dynamic optimization, the design for control (DFC) approach is used to integrate the structure and control for improving dynamic performance with reduced control torque. Finally, for a rapid 3D graphical based implementation of the system, high-level computer-aided rapid system integration (CARSI) technology is used to integrate the structure design, controller design, and system implementation into the design and analytical software environment based on Pro/engineer, XML syntax, Simmechanics, and Simulink. Thus, the development time for the LMTS is reduced.     

Operation analysis of a Chebyshev-Pantograph leg mechanism for a single DOF biped robot

In this paper, operation analysis of a Chebyshev-Pantograph leg mechanism is presented for a single degree of freedom (DOF) biped robot. The proposed leg mechanism is composed of a Chebyshev four-bar linkage and a pantograph mechanism. In contrast to general fully actuated anthropomorphic leg mechanisms, the proposed leg mechanism has peculiar features like compactness, low-cost, and easy-operation. Kinematic equations of the proposed leg mechanism are formulated for a computer oriented simulation. Simulation results show the operation performance of the proposed leg mechanism with suitable characteristics. A parametric study has been carried out to evaluate the operation performance as function of design parameters. A prototype of a single DOF biped robot equipped with two proposed leg mechanisms has been built at LARM (Laboratory of Robotics and Mechatronics). Experimental test shows practical feasible walking ability of the prototype, as well as drawbacks are discussed for the mechanical design.     

一自由度腿式行走机构的研究与设计

设计了一种一自由度腿式行走机构,机构由平面四杆机构和放大机构组成。首先基于契贝谢夫平面四杆机构特点,利用解析法,建立相应数学模型,得出运动学方程。其次利用Adams对行走轨迹进行仿真分析,讨论了连杆长度对运动轨迹的影响,并进行了运动学仿真研究。最后,通过系统仿真和搭建原型,验证了方案的正确性及机构设计的合理性。该机构的设计为开发新型的低功耗、低成本、易控制的腿式机器人提供设计了依据,实用可行。     

能效型步行机模型及其步态控制问题的计算机辅助研究

本文研究了机体坐标系型腿足机构步行机的能量效率问题, 提出了具有几个能动自由度的缩放式腿足机构昆虫姿态六足步行机模型, 研究了该模型的步态控制问题.最后, 用计算机仿真技术动态显示了该模型跨越障碍及在不平坦地面上的安全步行姿态.     

Spring equilibrator theory for static balancing of planar pantograph linkages

Static spring balancing theory for planar pantograph linkages is developed using a potential energy approach. Application of this theory achieves static balancing of pantograph linkages in a gravitational field throughout the full range of motion by guaranteeing perfect energy transfer between system gravitational and elastic potential energies. The general planar pantograph linkage is addressed by means of four pantograph types where each type represents a different revolute/prismatic joint arrangement. Equilibrator design for two of these pantograph types represents a first introduction of equilibrium theory to include linkages having prismatic pairs. Applications for walking machine leg design and for vertical plane selective compliance assembly robot design are discussed.     

Synthesis of function-generation mechanisms using variable length driving links

In this paper, a design method is proposed to solve function-generation problems for four-bar linkages without any limitation on the number of precision positions, using variable length driving links. A single degree-of-freedom (DOF) linkage mechanism, comprising the original four-bar linkage, a ternary link, a roller link, and a guiding slot in a fixed link, is employed to make the length of driving link variable while being driven by a power source. A new function-generation design process is also proposed. An nth-degree polynomial is utilized to design the contour of the guiding slot. Three examples are provided to verify the effectiveness of this technique, and the structural errors show significant improvement in all examples, compared to the conventional three precision-point solution.     

Wheelchair.q, a motorized wheelchair with stair climbing ability

The paper deals with Wheelchair.q, a concept for a stair climbing wheelchair capable of moving in structured and unstructured environments, climbing over obstacles and going up and down stairs.The design of the wheelchair, consisting of a frame, a seat and a four-bar linkage mechanism that connects frame and seat, is presented.The four-bar linkage moves and rotates the chair to prevent the wheelchair from overturning and to guarantee a comfortable posture to the passenger during different operations. The kinematic synthesis of the linkage mechanism is discussed using an algebraic method. When the wheelchair faces an obstacle such as a step or a stair, it can passively change locomotion mode, from rolling on wheels to walking on rotating legs, thanks to its self-adaptive locomotion units. The function of the locomotion unit is described and modeled using kinematic equations. The locomotion unit requires only one motor, for both wheeled and legged locomotion. Tests on a scale prototype were conducted in order to evaluate the effectiveness of this locomotion.     

Optimum synthesis of the four-bar function generator in its symmetric embodiment: the Ackermann steering linkage

The problem of optimum synthesis of the planar four-bar function generator is investigated and the practical case of the Ackermann steering linkage considered as an example. The reduced number of design parameters of this symmetric four-bar linkage allowed inspecting the design space of various types of objective functions through 3D representations, and their properties suggestively highlighted. For practical purposes, the numerical results were summarized in a set of parametric design-charts useful to the automotive engineer in conceiving the steering linkage of a new vehicle.     

足式机器人轻量化液压油源匹配设计方法研究

液压油源是足式机器人液压驱动系统的核心供能元件,将电能产生的机械能转化为油液的压力能,为驱动机器人各关节运动提供动力源。液压油源质量一般占据足式机器人整机质量超过20%,实现油源的轻量化,将有助于提升足式机器人的续航能力、机动性和承载能力。传统液压油源设计过程中更关注性能,在轻量化匹配设计方面还有待进一步完善。首先进行足式机器人轻量化液压油源的原理设计;其次将液压油源以功能为依据进行模块划分,分析液压油源各模块质量影响参数;针对质量与体积占比较大的电机泵进行匹配研究,针对蓄能器模块进行参数轻量化分析;针对集成阀块的轻量化设计,研究流道构建与元件排布原则;成功研发一种轻量化液压油源样机;最终形成了一种足式机器人轻量化液压油源匹配设计方法,有助于实现足式机器人液压驱动系统的轻量化。     

Performance evaluation and design optimization using differential evolutionary algorithm of the pantograph for the high-speed train

The global trend in the railway industry is the effort to increase the maximum speed and stability of a train. For an electric railway vehicle to meet this driving performance, stable electric power should be supplied by a catenary system. Various factors affect the current collection performance, most important of which is the dynamic characteristics of a pantograph. In this paper, the sensitivity analysis and design optimization of a pantograph for a high-speed train were conducted using a finite element method. The dynamic catenarypantograph interaction was analyzed by using the commercial finite element analysis software, SAMCEF. The pantograph was modeled as a three degrees of freedom mass-spring-damper system, and the pre-sag of the contact and messenger wire due to gravity was implemented. The span data of a high-speed line was applied in the analysis model. And the dynamic characteristics of the pantograph model were obtained by a performance test. The reliability of the simulation model was verified by comparing the analysis contact force results with the test data. By simulation, the mean contact force and its standard deviation etc. were evaluated, and then sensitivity of the pantograph was analyzed. Based on the sensitivity analysis results, the specification of the pantograph was optimized. In the optimization process, response surface analysis and differential evolutionary algorithm were applied to define the regressive function and to determine the optimum values for stable current collection performance. Finally, the improvement of the current collection performance was verified by comparing the optimum specification results with the original specification.     

Computer-aided design of a leg for an energy efficient walking machineLa conception assitee par ordinateur d'une jambe pour une machine marchante energetiquement efficace

Vehicles with legs instead of wheels have been studied for a number of years. One of the reasons for interest in such vehicles is that animals use only 10% as much energy as wheeled or tracked vehicles when traveling over rough terrain. The leg geometry is the most crucial aspect of the design since it strongly influences the efficiency of the vehicle. The legs should be simple in structure, and when the motion of the body is on a horizontal straight line, only one actuator per leg should be active in order to have good energy efficiency. The design of an energy efficient walking machine leg is described in this paper. In the design procedure, the motion of the leg is considered first, and a very simple leg developed from a 4-bar linkage and designed using a computer-aided interactive program is described. Second, the forces on this leg during a typical motion cycle are discussed. The leg is driven by a primary actuator for straight line walking and two secondary actuators which vary working height and change direction. A prototype of the leg is being built in The Department of Mechanical Engineering at The Ohio State University.     

转向装置球面四杆机构的综合

提出了采用球面四杆机构作为转向机构与方向盘之间的运动传递 ,并建立了车辆转向曲率与转向机构输入构件转角的关系。在此基础上获得了球面四杆机构输入—输出关系和机构优化综合数学模型 ,最后绘出误差曲线 ,以验证所提出方法的有效性。     

Angular velocity RCCC-linkage of a spherical four-bar linkageWinkelgeschwindigkeits-RCCC-getriebe eines sphärischen Viergelenkgetriebes

The angular velocity diagram of a spherical four-bar linkage is a tetrahedron in space. Based on this angular velocity tetrahedron an RCCC-linkage may be devised. The driving link of this RCCC-linkage rotates with the same angular velocity as that of the driving link of the original spherical four-bar. The linear displacement and the sliding velocity of the output link of the RCCC-linkage represent respectively the angular velocity and angular acceleration of the output link of the original spherical four-bar. The shape of the equivalent dual spherical four-bar linkage of the RCCC-linkage is identical with that of the original spherical four-bar linkage.     

断路器弹簧操动机构双四杆机构优化设计

断路器弹簧操动机构中四杆机构的结构参数直接影响着断路器动触头的速度和位移。很多厂家在生产弹簧操动机构过程中,四杆机构设计较多为经验设计,需要不断试验、修改、比较。为适应实际生产过程中不同机构输出要求,能够快速准确给出四杆机构系统的理论设计方法和修改方案尤为重要。文中通过分析四杆机构与断路器弹簧操动机构的输出特性的关系,按照输出力特性设计铰链四杆机构结构参数。基于粒子群优化算法求解计算结果,运用MATLAB编程设计图形用户界面。图形用户界面中通过调整相应参数可以快速修改方案并得到计算结果,使弹簧操动机构四杆机构设计直观方便。     

Reducing undesirable vibrations of planar linkage mechanism with joint clearance

An optimization design method is presented to reduce the undesirable vibrations caused by clearance for planar linkage mechanism. A clearance joint is defined and considered a contact/impact force constraint. Contact and impact force models for the clearance joint are established using a normal contact force model based on Hertz model with energy loss and a tangential friction model based on modified Coulomb model with dynamic friction coefficient, respectively. In view of the clearance joint, dynamic equations and optimization method for a planar four-bar mechanism are then presented as an application example. The optimization aims to minimize the maximum absolute acceleration peaks of the mechanism by determining the link lengths of the planar linkage mechanism. Finally, the optimization design is solved by a generalized reduced gradient algorithm. Results show evident decrease in vibration peaks of the mechanism and obvious reduction in the contact forces in the clearance joint, which contribute to a good performance of planar linkage mechanism systems.     

基于组合近似模型的可靠性优化方法在行人柔性腿型碰撞中应用研究

当行人与车辆发生碰撞时,车身最前端的部件将直接与行人下肢腿部发生接触,其设计是满足行人下肢保护要求的关键。然而针对传统要求的基于刚性腿型行人保护车辆前结构设计方法,在应对柔性腿型行人保护要求已呈现明显的局限性。为了提高保险杠结构的柔性腿型保护功能,结合试验设计技术、组合近似建模技术、多目标优化算法和可靠性分析方法,以行人腿部的伤害值最低为优化目标,对车辆前端结构参数进行可靠性优化设计并对优化结果进行试验验证。研究结果表明:优化后的车辆前端结构与原设计相比,行人柔性腿型保护功能得到明显提高,为车辆前端结构的设计与开发提供有效的参考。     

Analysis on the performance of the SLIP runner with nonlinear spring leg

The spring-loaded inverted pendulum(SLIP) has been widely studied in both animals and robots.Generally,the majority of the relevant theoretical studies deal with elastic leg,the linear leg length-force relationship of which is obviously conflict with the biological observations.A planar spring-mass model with a nonlinear spring leg is presented to explore the intrinsic mechanism of legged locomotion with elastic component.The leg model is formulated via decoupling the stiffness coefficient and exponent of the leg compression in order that the unified stiffness can be scaled as convex,concave as well as linear profile.The apex return map of the SLIP runner is established to investigate dynamical behavior of the fixed point.The basin of attraction and Floquet Multiplier are introduced to evaluate the self-stability and initial state sensitivity of the SLIP model with different stiffness profiles.The numerical results show that larger stiffness exponent can increase top speed of stable running and also can enlarge the size of attraction domain of the fixed point.In addition,the parameter variation is conducted to detect the effect of parameter dependency,and demonstrates that on the fixed energy level and stiffness profile,the faster running speed with larger convergence rate of the stable fixed point under small local perturbation can be achieved via decreasing the angle of attack and increasing the stiffness coefficient.The perturbation recovery test is implemented to judge the ability of the model resisting large external disturbance.The result shows that the convex stiffness performs best in enhancing the robustness of SLIP runner negotiating irregular terrain.This research sheds light on the running performance of the SLIP runner with nonlinear leg spring from a theoretical perspective,and also guides the design and control of the bio-inspired legged robot.     

六足步行机缩放式腿机构的计算机辅助设计

本文分析了六足步行机圆柱型缩放式腿机构的运动规律及其受力状况,并结合机构的运动空间、六足步行机的最佳机体高度及结构约束等条件,给出了一种合理选择这种机构各设计参数的优化设计方法及计算实例。     

仿驼足车辆行走机构的设计与试验

研制高通过性的沙漠车辆行走机构,是解决沙漠地区交通运输问题的关键,对加快沙漠资源的开发和利用具有重要的意义。对驼足结构、驼足与沙地独特作用方式进行了分析。根据仿生原理,首次提出了两种新型车辆行走机构;仿驼步行足和仿驼足轮胎的设计原理。研制了仿驼步行足和仿驼足橡胶轮胎,并进行了牵引性能试验。结果表明,２种车辆行走机构牵引性能良好,从而为研制和开发步行车辆和沙漠车辆奠定了基础。     

四杆直线导向机构综合新方法的研究

提出了四杆直线导向机构综合的数值比较法,运用鲍尔点附近的连杆曲线以３阶精度逼近给定的直线,建立起了连杆曲线中具有直线段的四杆机构数据库。将给定的直线段条件与数据库中的参数进行比较,即可得到一系列满意的四杆直线导向机构。该数值比较法解决了四杆直线导向机构综合的难题。应用该方法编制了一套四杆直线导向机构综合的设计软件,对单、双直线导向机构进行了综合与仿真,实现了导路上无摩擦、磨损的四杆直线导向机构综合的自动化与可视化,大大缩短了设计周期。