一种波纹管蛇形机器人的结构设计及运动分析

针对仿蛇机器人结构复杂,关节寿命短的问题,文中设计一款波纹管蛇形机器人结构.利用Solidworks建立蛇形机器人三维模型,然后构建了蛇形机器人的D-H坐标系及简化模型,并对模型进行了关节约束分析及动力学分析,推导了波纹管蛇形机器人的动力学模型.并且通过ANSYS和Adams对蛇形机器人进行了磨损仿真和运动仿真,仿真结果表明,波纹管避免了蛇形机器人直接与地面接触,减少了蛇形机器人的运动磨损量,提高了使用寿命,且在运动时其速度、加速度过渡平滑,速度能在1s内达到最大值100mm/s,在零点处无反向变化;力矩变化无冲击,蛇体长度变化平稳,无侧滑及停滞等不正常状态,运动效果较好.     

蛇形蠕动机器人行波运动和动力学研究

根据自然界蛇的体骨结构,建立了一种串联连杆结构的蛇形机器人,连接处选用双轴舵机,起到旋转副的作用。在Serpenoid曲线的蠕动步态模型基础上,利用MATLAB对进行仿真,分析了关键参数对蛇形曲线的影响,分析了曲线离散化对蛇形曲线的影响,通过Adams对蛇形机器人的行波运动进行了动力学仿真,分析了蛇形机器人在行波向前时特定关节与地面的作用力和关节扭矩情况。     

小型蛇形机器人的蠕动运动分析与仿真

提出一种由8个关节组成的小型蛇形机器人,研究了蛇形机器人关节轴平行于地面的蠕动运动机理。依据蜿蜒曲线理论,对蛇形机器人蠕动的运动学和动力学进行了分析与仿真,得出了蠕动运动轨迹和所需最大驱动力矩,验证了蠕动运动轨迹规划方案的可行性。     

蛇形机器人蜿蜒运动的摩擦机理及推进条件

针对带有从动轮的蛇形机器人,考虑实际结构中从动轮在蛇形机器人关节连杆上的安装位置,建立蛇形机器人蜿蜒运动的动力学模型。提出一种库伦-粘滞混合摩擦力模型,整体的库伦摩擦力特性和临界点处的粘滞摩擦力特性,避免了库伦摩擦力模型本身的非光滑性,以提高动力学模型的求解效率与计算稳定性。基于改进的动力学与摩擦力模型,利用摩擦系数比来表征法向与切向摩擦力的各向异性程度,通过对蜿蜒运动的仿真分析,讨论了摩擦系数比对前向运动速度与推进效率的影响规律,并对运动过程中蛇形机器人各个关节模块的速度和摩擦力变化进行了分析,明确了蛇形机器人蜿蜒运动的摩擦学机理,解释了蛇的蜿蜒抬起运动能够有效减少摩擦阻力而适用于高速运动的原因。最后通过带从动轮的蛇形机器人样机实验,对实现蜿蜒运动的摩擦学推进条件进行了验证。研究对于实现蛇形机器人的结构优化,步态规划与运动控制具有重要的理论意义与实际指导价值。     

一种蛇形机器人的直线蜿蜒运动规划

针对蛇形机器人的蜿蜒运动,分析了其运动机理,在虚拟样机软件中导入了蛇形机器人结构模型,建立了动力学方程,对蛇形机器人的运动轨迹进行了规划,分析了关节角度函数中转角幅值、摆动频率、相位差、比例因子以及静摩擦系数对其运动轨迹的影响。结果表明,通过合理设置关节角度函数中的各个参数,能保证蛇形机器人的运动具有基本的稳定性,且一定范围内的参数变化能实现最佳直线蜿蜒运动。最后,给出了各个关节的驱动力矩,为驱动机构的选型和物理样机的加工提供了理论依据。     

六足矿井搜救探测机器人越障动力学建模与分析

研究了一种六足矿井搜救探测机器人的越障动力学问题。首先分析了机器人翻越垂直障碍的过程,进而构建了越障过程中不同步态时的动力学模型。该模型可以确定机器人所需的驱动力矩与几何尺寸、运动参数、障碍高度及摩擦因数之间的关系。通过不同步态的动力学分析,确定了机器人在越障过程中驱动力矩变化趋势。此结果为矿井搜救探测机器人在未知环境下越障步态的选择及优化提供了理论基础和依据。     

主动磁悬浮轴承系统保护轴承碰撞特性研究

以立式磁悬浮轴承系统为研究对象,建立转子跌落过程的碰撞模型和动力学仿真模型,研究转子跌落时的动力学响应和不同初始转速、碰撞面摩擦因数对转子跌落到保护轴承上产生最大碰撞力的影响规律,并进行转子跌落试验,以评价保护轴承的抗跌落性能。结果表明：随着转子初始转速从0增加至30 000 r/min,最大径向碰撞力从0增加至2 344 N,最大轴向碰撞力基本不变;随着碰撞面摩擦因数的增大,最大径向碰撞力随之增大,而最大轴向碰撞力基本不变;最大轴向碰撞力均发生在首次碰撞,保护轴承的最大接触应力均远小于许用应力;导致保护轴承失效的最主要原因是碰撞面间的滑动摩擦生热,为应对摩擦热带来的不利影响,提高保护轴承的抗跌落性能,可对保护轴承的碰撞面进行表面处理。     

蛇类表皮的生物摩擦学性能研究

使用自行设计的一种往复运动的微摩擦测试装置,考察不同介质环境下,蛇类表皮及其表皮的摩擦特性。研究结果表明:在干摩擦下,蛇向后运动时的摩擦因数是前向运动的摩擦因数的1.2~4.1倍;在液体环境下向前运动时的摩擦因数是向后运动的摩擦因数的1.2~2.55倍,表现出摩擦各向异性。液体环境下,蛇类自身的分泌物在蛇运动时形成了以边界膜和流体膜为主的混合润滑,且边界膜破裂的概率不大。当蛇表皮面由于弹性变形或其它原因使表面速度随位置而变化时因各断面的流量不同而产生压力流动,从而在液体环境下,向后运动的摩擦力逐渐减小,甚至小于向前运动的摩擦力。     

一种可重构蛇形机器人的研究

提出了一种新型的可重构蛇形机器人机构。该机构主要特点是单关节结构模块化，具有可适应地面形状变化的柔性连接环节和类似于蛇腹鳞摩擦特性的机构底部，手动可重构，当单自由度关节轴线互相平行连接时，该机构可实现多种平面运动形式，当单自由度关节轴线垂直依次连接时，形成的蛇形机器人具有两自由度的关节，可进行多种空间运动。试验结果证实，该蛇形机构重量轻，控制简单，运动灵活，能够很好地仿生蛇的多种运动形式。     

基于ADAMS的蛇形机器人运动仿真研究

本文主要对蛇形机器人关节结构进行模块化设计,对结构特点进行分析,给出结构参数。对蛇形机器人主要的爬坡运动进行运动分析和动作规划,并利用ADAMS软件对运动情况进行仿真,分析了爬坡运动参数和关节力矩变化情况,为蛇形机器人的运动规划提供了较为完整的技术依据。     

蛇形机器人跟踪误差预测的自适应轨迹跟踪控制器

为了满足蛇形机器人轨迹跟踪运动的精度需要,消除外界干扰对机器人跟踪误差的影响,提出了一种蛇形机器人跟踪 误差预测的自适应轨迹跟踪控制器。 所提出的控制器实现了机器人干扰变量、摩擦系数和控制参数的预测,并用预测值和虚拟 控制函数来补偿系统的控制输入,抵消了蛇形机器人在轨迹跟踪过程中的侧滑角,避免了干扰变量对机器人带来的负面影响, 提高了轨迹跟踪的误差稳定性与控制精度。 在建立蛇形机器人模型后,利用积分形式的侧滑角补偿项改进了视线法,并设计了 蛇形机器人的自适应轨迹跟踪控制器。 使机器人的位置误差在 10 s 内实现收敛,角度误差小于 0. 03 rad,预测值误差在 5 s 内 收敛。 通过仿真实验,验证了所提出的控制器的有效性和优越性。     

Energetic walking gaits studied by a simple actuated inverted pendulum model

The mechanical structure and the joint torques configuration are the important parts in the biped robot design. Meanwhile, different walking speed and step length should be chosen to achieve efficient gait according to different need of walking environment. Therefore, this paper investigates the energetic walking gaits using a simple actuated inverted pendulum model. Joint torques and push-off impulse are both added in the model. The walking gaits with different joint torques configuration and with different combination of walking speeds and step lengths are analyzed. The results show that hip velocity direction is changed by the push-off impulse just before the heelstrike, which reduces the energy consumption of each step. The walking gait with minimal energy consumption is the walking pattern only with push-off, the energy cost of which is 1/4 of the walking pattern only with joint torque during the swing phase. The cost of transport (COT) and the push-off impulse of the walking gait is increasing with the increase of walking speed and step length. Using same value of push-off impulse, the walking with long step length and slow speed is more efficient. The paper can provide suggestions for designing advanced legged robot systems with high energy efficiency and various gaits. For example, the consideration of push-off mechanism can be used in the biped robots design.

     

考虑温度影响的机器人关节摩擦模型

为描述连续运转下的温度对串联机器人关节摩擦的影响,提出一种考虑温度影响的关节摩擦模型。该摩擦模型可在无需对温度进行测量或估计的前提下描述关节温度变化对关节摩擦的影响。通过实验测量了机器人关节在不同角速度下连续运转时的摩擦力矩,并基于理论模型对数据进行了拟合。实验结果对比验证了该关节摩擦模型的有效性,且该模型能较为准确地描述连续运转下关节摩擦力矩的变化。     

仿人型跑步机器人矢状面起跳运动的实现

针对仿人型跑步机器人实现起跳动作时没有考虑腿部质量或将机器人质心固定在身体上某点的不足,提出了一种新的方法实现跑步机器人矢状面内的起跳动作:利用“虚拟腿”的概念,求出机器人质心的轨迹,然后对某些广义坐标进行规划,通过求解非线性方程组计算出机器人在每个时刻的运动学参数。最后根据动力学方程求出各个关节的驱动力矩。仿真结果表明:机器人跑步时各个关节角度和关节驱动力矩变化平稳,因此起跳动作设计合理。     

Driving Torque Reduction in Linkage Mechanisms Using Joint Compliance for Robot Head

The conventional linkage mechanisms with compliant joint have been widely studied and implemented for increasing the adaptability of the mechanism to external contacts. However, the analysis of how compliant joints in linkage mechanism can reduce the energy consumption isn't still studied deeply. In a mobile service robot head, the actions of blinking the eyes and moving the eyeballs are realized by the planar linkage mechanism respectively. Therefore, minimizing the driving torques through motion trajectories for the linkage mechanism, which will be beneficial to extend the working time for mobile service robots. The dynamic modeling of the linkage mechanism with springs-loaded compliant joint is established. An optimization procedure for obtaining the optimal parameters of springs is proposed for minimizing the max value of driving torques within a range of desired operating conditions. The Simulations prove that the linkage mechanism with compliant joints can effectively reduce the driving torques, and reduce the energy consumption consequently. The framework can also be applied in other similar applications to reduce the driving torque and save energy. Compared with previous efforts, this is the first attempt that the linkage mechanism with complaint joint is applied in the robot head for reducing the driving torque.     

一种PR结构蛇形机器人的结构优化设计

根据仿生蛇多冗余、多自由度的特点,提出了PR结构蛇形机器人机械机构。该机构的主要特点是关节机构的模块化,每个关节具有3个自由度,关节结构中采用了弹簧零件,每个关节有2个电机。在电机没有力作用的情况下,弹簧通过预紧力恢复至初始位置,不需要电气和程序控制,大大简化了操作流程。蛇体运行更加贴合外环境表面,增加了其执行任务过程中的稳定性。突破性实现了轴向伸缩、背部腹部弯曲等功能体态。     

Method for analyzing articulated torques of heavy-duty six-legged robot

The accuracy of an articulated torque analysis influences the comprehensive performances of heavy-duty multi-legged robots. Currently, the extremal estimation method and some complex methods are employed to calculate the articulated torques, which results in a large safety margin or a large number of calculations. To quickly obtain accurate articulated torques, an analysis method for the articulated torque is presented for an electrically driven heavy-duty six-legged robot. First, the rearmost leg that experiences the maximum normal contact force is confirmed when the robot transits a slope. Based on the ant-type and crab-type tripod gaits, the formulas of classical mechanics and MATLAB software are employed to theoretically analyze the relevant static torques of the joints. With the changes in the joint angles for the abductor joint, hip joint, and knee joint, variable tendency charts and extreme curves are obtained for the static articulated torques. Meanwhile, the maximum static articulated torques and the corresponding poses of the robot are also obtained. According to the poses of the robot under the maximum static articulated torques, ADAMS software is used to carry out a static simulation analysis. Based on the relevant simulation curves of the articulated torques, the maximum static articulated torques are acquired. A comparative analysis of the maximum static articulated torques shows that the theoretical calculation values are higher than the static simulation values, and the maximum error value is approximately 10%. The proposed method lays a foundation for quickly determining accurate articulated torques to develop heavy-duty six-legged robots.     

COMBINING INTERNAL AND EXTERNAL ROBOT MODELS FOR IMPROVED MODEL PARAMETER ESTIMATION

Experimental robot identification techniques can principally be divided into two categories, based on the type of models they use : internal or external. Internal models relate the joint torques or forces and the motion of the robot; external models relate the reaction forces and torques on the bedplate and the motion data. This paper describes how internal and external robot models can be combined into one identifiable minimal model. This model allows to combine joint torque/force and reaction torque/force measurements in one parameter estimation scheme. This combined model estimation will yield more accurate parameter estimates, and consequently better actuator torque predictions, which is shown by means of a simulated experiment on an industrial robot (KUKA IR 361). This increased accuracy is quite interesting in view of using advanced control algorithms such as computed torque control.