Energy Efficiency Analysis of Quadruped Robot with Trot Gait and Combined Cycloid Foot Trajectory

Quadruped robots consume a lot of energy, which is one of the factors restricting their application. Energy efficiency is one of the key evaluating indicators for walking robots. The relationship between energy and elastic elements of walking robots have been studied, but different walking gait patterns and contact status have important influences on locomotion energy efficiency, and the energy efficiency considering the foot-end trajectory has not been reported. Therefore, the energy consumption and energy efficiency of quadruped robot with trot gait and combined cycloid foot trajectory are studied. The forward and inverse kinematics of quadruped robot is derived. The combined cycloid function is proposed to generate horizontal and vertical foot trajectory respectively, which can ensure the acceleration curve of the foot-end smoother and more successive, and reduce the contact force between feet and environment. Because of the variable topology mechanism characteristic of quadruped robot, the leg state is divided into three different phases which are swing phase, transition phase and stance phase during one trot gait cycle. The non-continuous variable constraint between feet and environment of quadruped robot is studied. The dynamic model of quadruped robot is derived considering the variable topology mechanism characteristic, the periodic contact and elastic elements of the robot. The total energy consumption of walking robot during one gait cycle is analyzed based on the dynamic model. The specific resistance is used to evaluate energy efficiency of quadruped robot. The calculation results show the relationships between specific resistance and gait parameters, which can be used to determine the reasonable gait parameters.

An energy efficiency evaluation method for parallel robots based on the kinetic energy change rate

Benefit from the high payload-to-weight ratio, parallel robots are expected to have a high potential for energy savings. However,it is a challenging issue to evaluate the energy efficiency of parallel robots with a quantitative method. Quantitative energy efficiency evaluation methods include energy efficiency evaluation models and indices which mathematically describe the relationship between energy consumers in models and design variables of robots, such as geometry, mass and inertia parameters.Considering the structural features of parallel robots, the chains and the end effectors are identified as two separated energy consumers. Besides, the chains in parallel robots are identified as a transmission system which transfers energy from drives to the end effectors. On this basis, an energy efficiency evaluation model considering the change rate of kinetic energy stored in chains is built. The kinetic energy change rate of chains is influenced by design variables of robots as well as motion of the end effector.In order to give a quantitative description of energy efficiency performance of parallel robots, indices considering arbitrary velocity vector of the end effector are proposed. The evaluation method is suitable for all kinds of parallel robots with various motion conditions. Furthermore, the method can be used to optimize machining parameters and guide the design of energyefficient machines.

Optimal Energy Efficiency Based High-speed Flying Control Method for Hydraulic Quadruped Robot

Herein,a control method based on the optimal energy efficiency of a hydraulic quadruped robot was proposed,which not only realizes the optimal energy efficiency of flying trot gait but also ensures the stability of high-speed movement.Concretely,the energy consumption per unit distance was adopted as the energy efficiency evaluation index based on the constant pressure oil supply characteristics of the hydraulic system,and the global optimization algorithm was adopted to solve the optimal parameters.Afterward,the gait parameters that affect the energy efficiency of quadruped were analyzed and the mapping relationship between each parameter and energy efficiency was captured,so as to select the optimum combination of energy efficiency parameters,which is significant to improve endurance capability.Furthermore,to ensure the stability of the high-speed flying trot gait motion of the hydraulic quadruped robot,the active compliance control strategy was employed.Lastly,the proposed method was successfully verified by simulations and experiments.The experimental results reveal that the flying trot gait of the hydraulic quadruped robot can be stably controlled at a speed of 2.2 m/s.

Piezoelectric soft robot driven by mechanical energy

Power sources and energy-harvesting schemes are still grand challenges for soft robots.Notably,compared with other power sources,triboelectric nanogenerators(TENGs)have shown great potential because of their low manufacturing and fabrication costs,outstanding resilience,remarkable stability,and environmental friendliness.Herein,a triboelectric effect-driven piezoelectric soft robot(TEPSR)system is proposed,which integrates a rotary freestanding triboelectric nanogenerator(RFTENG)to drive a soft robot comprising a piezoelectric unimorph and electrostatic footpads.Based on the natural triboelectrification,through converting mechanical energy into electricity,TENG provides a unique approach for actuation and manipulation of the soft robot.The perfect combination provides the most straightforward way for creating a self-powered system.Experimentally,under the power of RF-TENG,the soft robot reaches a maximum moving speed of 10 cm per second and a turning rate of 89.7°per second,respectively.The actuation and manipulation demonstration are intuitively accomplished by maneuvering the robot around a maze with a 71 cm track within 28 s.For autonomous feedback controls,one practical application is carrying two infrared sensors on board to realize obstacle avoidance in an unstructured environment.Moreover,a micro-camera was equipped with the soft robot to provide real-time“first-person”video streaming,enhancing its detection capability.

Efficient Dynamic Locomotion of Quadruped Robot via Adaptive Diagonal Gait

Quadruped animals in the nature realize high energy efficiency locomotion by automatically changing their gait at different speeds.Inspired by this character,an efficient adaptive diagonal gait locomotion controller is designed for quadruped robot.A unique gait planning method is proposed in this paper.As the speed of robot varies,the gait cycle time and the proportion of stance and swing phase of each leg are adjusted to form a variety of gaits.The optimal joint torque is calculated by the controller combined with Virtual Model Control(VMC)and Whole-Body Control(WBC)to realize the desired motion.The gait and step frequency of the robot can automatically adapt to the change of speed.Several experiments are done with a quadruped robot made by our laboratory to verify that the gait can change automatically from slow-trotting to flying-trot during the period when speed is from 0 to 4 m/s.The ratio of swing phase is from less than 0.5 to more than 0.5 to realize the running motion with four feet off the ground.Experiments have shown that the controller can indeed consume less energy when robot runs at a wide range of speeds comparing to the basic controller.

Effect of Flexible Spine Motion on Energy Efficiency in Quadruped Running

Energy efficiency is important in the performance of quadruped robots and mammals. Flexible spine motion generally exists in quadruped mammals. This paper mainly explores the effect of flexible spinal motion on energy efficiency. Firstly, a planar simplified model of the quadruped robot with flexible spine motion is introduced and two simulation experiments are carried out. The results of simulation experiments demonstrate that both spine motion and spinal flexibility can indeed increase energy efficiency, and the curve of energy efficiency change along with spinal stiffness is acquired. So, in order to obtain higher energy efficiency, quadruped robots should have flexible spine motion. In a certain speed, there is an optimal spinal stiffness which can make energy efficiency to be the best. Secondly, a planar quadruped robot with flexible spine motion is designed and the conclusions drawn in the two simulation experiments are verified. Lastly, the third simulation experiment is carried out to explore the relationship between the optimal spinal stiffness, speed and total mass. The optimal spinal stiffness increases with both speed and total mass, which has important guiding significance for adjusting the spinal stiffness of quadruped robots to make them reach the best energy efficiency.

Energy Analysis of a CPG-controlled Miniature Robotic Fish

Bionic robotic fish has a significant impact on design and control of innovative underwater robots capable of both rapid swimming and high maneuverability. This paper explores the relationship between Central Pattern Generator （CPG） based locomotion control and energy consumption of a miniature self-propelled robotic fish. To this end, a real-time energy measurement system compatible with the CPG-based locomotion control is firstly built on an embedded system. Then, tests are conducted on the untethered actual robot. The results indicate that different CPG feature parameters involving amplitude, frequency, and phase lag play distinct roles in energy consumption under different swimming gaits. Specifically, energy consumption is positively correlated with the changes in the amplitude and frequency of CPGs, whereas the phase lag of CPGs has little influence on the energy consumption. It may offer important inspiration for improving energy efficiency and locomotion performance of versatile swimming gaits.

Redundancy in Biology and Robotics:Potential of Kinematic Redundancy and its Interplay with Elasticity

Redundancy facilitates some of the most remarkable capabilities of humans,and is therefore omni-present in our physiology.The relationship between redundancy in robotics and biology is investigated in detail on the Series Elastic Dual-Motor Actuator(SEDMA),an actuator inspired by the kinematic redundancy exhibited by myofibrils.The actuator consists of two motors coupled to a single spring at the output.Such a system has a redundant degree of freedom,which can be exploited to optimize aspects such as accuracy,impedance,fault-tolerance and energy efficiency.To test its potential for human-like motions,the SEDMA actuator is implemented in a hopping robot.Experiments on a physical demonstrator show that the robot's movement patterns resemble human squat jumps.We conclude that robots with bio-inspired actuator designs facilitate human-like movement,although current technical limitations may prevent them from reaching the same dynamic and energetic performance.

偕老同穴海绵启发的仿生结构吸能特性研究

目的为得到质量更轻、吸能效果更好的结构,以自然界中偕老同穴海绵复杂硅质骨针结构为仿生原型,提出一种偕老同穴海绵仿生吸能结构。方法通过有限元仿真对偕老同穴仿生结构和4种对比结构进行准静态压缩仿真,并在此基础上分析不同构型参数对海绵仿生结构吸能性能的影响。结果结果表明,偕老同穴海绵仿生结构在压缩过程中呈现二次受力平台效应,使得其吸能效果优于传统结构,同时当斜肋板位置系数Rkl为0.3时仿生结构的吸能效果最佳。随着斜肋板厚度的增大,结构的比吸能线性增加。从压溃力效率来看,当斜肋板厚度是纵横筋板厚度的1.6倍时,结构的压溃力峰值基本等于平均压溃力,结构压溃力效率达到最优,结构的整体吸能性能效果达到最优。结论本文所提出偕老同穴海绵仿生结构为高刚轻质吸能结构设计提供了参考,在吸能防护领域具有一定的应用前景。

液压四足机器人油源流量自适应控制研究

在保证机器人正常运行的前提下,为了控制方便,通常液压四足机器人的油源采用恒压恒流的供能方式,这将会导致机器人驱动功率远低于油源提供的功率,造成了严重的能源浪费。为了减小能量损失,提出变流量动态供油策略。介绍油源的变流量控制基本原理,通过负载预测得到各个液压缸速度大小,再结合阀控缸的数学模型推算出单腿在运动过程中实时供油流量需求,并建立仿真模型与机器人样机实验验证流量自适应控制的有效性。实验结果表明:利用油源流量自适应控制策略,液压四足机器人的节能效率相比恒流量供能系统提高了56.51%。

Bionic Design and Simulation Analysis of Energy⁃Efficient and Vibration⁃Damping Walking Mechanism

African ostrich can run for 30 min at a speed of 60 km/h in the desert,and its hindlimb has excellent energy saving and vibration damping performance.In order to realize the energy⁃efficient and vibration⁃damping design of the leg mechanism of the legged robot,the principle of engineering bionics was applied.According to the passive rebound characteristic of the intertarsal joint of the ostrich foot and the characteristic of variable output stiffness of the ostrich hindlimb,combined with the proportion and size of the structure of the ostrich hindlimb,the bionic rigid⁃flexible composite legged robot single⁃leg structure was designed.The locomotion of the bionic mechanical leg was simulated by means of ADAMS.Through the motion simulation analysis,the influence of the change of the inner spring stiffness coefficient within a certain range on the vertical acceleration of the body centroid and the motor power consumption was studied,and the optimal stiffness coefficient of the inner spring was obtained to be 200 N/mm,and it was further verified that the inner and outer spring mechanism could effectively reduce the energy consumption of the mechanical leg.Simulation results show that the inner and outer spring mechanism could effectively reduce the motor energy consumption by about 72.49%.

基于全智能冲洗工艺的节能增效机器人智慧管控系统

设计一款冷端机器人智慧管控冲洗系统,实现对冷端设备的定期、全面清洗,提高设备工作效率,延长设备使用寿命,降低能源消耗和维护、维修成本。阐述系统设计思路和方案,介绍系统温度获取模块、传动模块以及机器人冲洗模块的设计要点。

考虑能耗的仿生软夹生产线瞬态性能分析

面向2035的高端装备制造以智能化、少人化和绿色化作为其重要指标,而仿生机械具有可植入工业控制算法、可替代传统人工的特点,使其受到了广泛关注。软夹是仿生机械手臂的核心组件,由包含聚二甲基硅氧烷(PDMS)和碳纳米管(CNT)材料的双层材料复合加工而成。为了生产具有较高定制化特性的软夹部件,其制造过程通常采用多台3D打印机串接的方式进行。而此类加工设备能耗较高,因此软夹生产需同时考虑产出率和能源消耗。针对典型仿生软夹生产系统,构建了双伯努利机器串行生产线模型,并得到其瞬态性能分析与期望能耗的计算公式,可用于求解该生产系统的瞬时生产率、原材料消耗率、在制品数量以及设备的饥饿率和阻塞率。根据设备工况提出了两种不同的控制策略用于降低实际生产过程中的设备耗能,并设计了数值算例以比较不同策略对生产系统能耗的影响。此外,通过建立产线的仿真模型,进一步验证了该理论算法的有效性。

轮腿式机器人轮-腿高效移动策略优化

复杂地形下的高效移动策略是轮腿式机器人研制过程中的技术难点。本文在常规移动策略的基础上,通过引入关节空间状态量描述支腿相对于机身的位姿,引入位姿转换量描述相邻时序的位姿状态量间的运动过程,进而建立起移动策略与时间和能耗的数学模型,并以移动时间最短和能耗最低为目标,建立了移动策略的优化模型,通过优化迭代形成轮-腿高效移动策略。复杂地形下的越障仿真表明,机器人采用轮-腿高效移动策略可实现越障功能,与常规移动策略相比,移动时间及能耗均明显降低,验证了轮-腿高效移动策略的有效性。

融合能耗指标与安全因子的移动医疗机器人通用路径规划

考虑在突发重大公共卫生事件期间存在的医疗物资搬运工作强度大、交叉传播风险高等问题,提出一种节能、安全且通用的移动医疗机器人无碰撞路径规划方法。首先,通过建立某方舱医院栅格地图环境模型,表征机器人自主移动过程的能量消耗指标,改进A*算法原始搜索方向,构建了一种计及能量因素的邻接矩阵优化策略。然后提出一种邻接矩阵权值算子,融合权值算子和安全避障惩罚因子到A*算法的估价函数中。同时,提出一种基于三次连续贝塞尔曲线的路径平滑方法,用于方舱医院栅格地图中生成曲率连续的平滑路径。仿真结果验证了所提方法的适用性,相较于传统路径规划方法,该方法具备节能性、安全性和平滑性特征,有效降低了医疗运输成本。

基于理想推进器理论的尾鳍推力与效率估算

鱼类尾鳍的动力学问题已经得到广泛研究,但是在进行尾鳍推进器的设计时,还缺乏一种简单有效的设计和估算方法,将尾鳍的运动参数与推力、效率联系起来;在观测和分析尾鳍流场的基础上,研究了2自由度尾鳍推进器的流场结构和推力形成原因;将理想推进器理论应用于尾鳍推进器的推力和效率计算,提出了射流及其诱导速度的量化假设,建立了推力、效率与运动参数、斯特劳哈尔数之间的函数关系;运用该函数对海洋动物的典型运动状态进行了估算,估算结果与动物观测现象基本吻合,该方法在机器鱼模型设计中得到了应用和验证。

基于波浪能获取的多关节仿生机器鱼能源自给系统

为解决仿生机器鱼水下长期服役的能源瓶颈问题,提出利用波浪能摆动关节来发电的多关节仿生机器鱼能源自给系统.根据随机波浪理论分析了海浪的频谱特性和获能潜力,设计了利用关节摆动发电的能源获取系统,并建立该系统的机电模型.最后,通过仿真模拟和单关节摆动发电试验验证了该方法的可行性,为仿生机器鱼水下长期服役的能源自给系统设计提供了参考.

土壤深松技术及高效节能仿生研究的发展

深松技术是旱地保护性耕作体系中的重要技术措施之一,高效节能是深松技术的发展方向。本文介绍了土壤深松的作用、深松机具类型和深松机具高效节能技术措施研究及应用现状;分析了基于土壤洞穴动物足趾结构和力学性能的深松机具仿生研究的发展趋势。

中华绒螯蟹平面运动三维观测和动力学分析

为给适应复杂路面的多足仿生机器人或步行移动平台的研究提供理论依据,该文以中华绒螯蟹为研究对象,使用三维运动图像采集系统采集其运动图像,并使用三维运动图像分析系统得到中华绒螯蟹质心的运动学参数,分析结果表明:中华绒螯蟹在平面运动时主要使用跳跃步态;质心动能、重力势能以及总机械能呈正弦波动,动能与重力势能同相;使用恢复系数表示动能和重力势能相互转换的效率,其平均值为31.73%±17.29%,恢复系数和平均速率没有相关关系;质心机械能比质量功率随平均速率的增长呈线性增加;质心水平动能比质量功率和重力势能比质量功率对中华绒螯蟹身体的加速和抬升起主要作用。该研究可为研究适应复杂路面的仿生机器人或移动平台提供理论依据。

履带式煤矿救灾机器人系统效率模型分析

对履带式煤矿救灾机器人的能量传递过程进行了理论分析,得到了各环节的效率公式,尤其对行走机构的效率进行了详细的分析,并据此建立了机器人系统综合效率的模型。通过对模型的分析发现,可以通过对放电电流的控制优化来提高机器人能量使用效率。进一步仿真得到履带式机器人系统效率和电流、电池容量的关系,结论可以为建立机器人能耗模型、提高机器人系统效率提供理论依据。