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Variable-model SMA-driven spherical robot

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Science China(Technological Sciences) 2019年第8期62卷 1401-1411页

作者： PAN Jie SHI ZhenYun wang tianmiao Robotic Laboratory Beihang University

In this paper, we introduce a bionic spherical robot. This research has been inspired by the muscular organs and modularity of organisms such as starfish and octopuses. The robot that we fabricated uses five soft feet to crawl like a starfish, and the robotic feet are driven by the shape memory alloy springs. The robotic spherical structure and the soft feet were fabricated by 3 D printing. The robotic feet were made of silicone gel;these feet could bend upward and downward to help the robot to crawl on the ground and roll down a slope. The shell separation module installed inside the robot could divide the robot into two identical modules, and this smart structure could enhance the robotic flexibility in a small space. We performed force analysis and robotic simulation, and the results verified the feasibility of the model. The robot can switch between rigidity and softness by using human control. Three types of gaits have been proposed for controlling robotic movement and improving robotic flexibility in movement;these include rolling, crawling, and avoiding obstacles. The results of this study indicate that the variable-model design of the robot is an effective way to enhance the flexibility of soft robots.

关键词： bionic robot soft animals shape memory alloy smart structure variable model

Dynamic Bending of Bionic Flexible Body Driven by Pneumatic Artificial Muscles(PAMs) for Spinning Gait of Quadruped Robot

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Chinese Journal of Mechanical Engineering 2016年第1期29卷 11-20页

作者： LEI Jingtao YU Huangying wang tianmiao School of Mechatronic Engineering and Automation Shanghai University School of Mechanical Engineering and Automation Beihang University

The body of quadruped robot is generally developed with the rigid structure. The mobility of quadruped robot depcnds on the mechanical properties of the body mechanism, It is difficult for quadruped robot with rigid structure to achieve better mobility walking or running in the unstructured environment. A kind of bionic flexible body mechanism for quadruped robot is proposed, which is composed of one bionic spine and four pneumatic artificial muscles（PAMs）. This kind of body imitates the four-legged creatures＇ kinematical structure and physical properties, which has the characteristic of changeable stiff＇hess, lightweight, flexible and better bionics. The kinematics of body bending is derived, and the coordinated movement between the flexible body and legs is analyzed. The relationship between the body bending angle and the PAM length is obtained. The dynamics of the body bending is derived by the floating coordinate method and Lagrangian method, and the driving tbrce of PAM is determined. The experiment of body bending is conductcd, and the dynamic bending characteristic of bionic flexible body is evaluated. Experimental results show that the bending angle of the bionic flexible body can reach 18. An innovation body mechanism for quadruped robot is proposed, which has the characteristic of flexibility and achieve bending by changing gas pressure of PAMs. The coordinated movement of the body and legs can achieve spinning gait in order to improve the mobility of quadruped robot.

关键词： quadruped robot bionic flexible body PAM spinning gait dynamics

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

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Chinese Journal of Mechanical Engineering 2014年第1期27卷 138-145页

作者： LEI Jingtao wang Feng YU Huangying wang tianmiao YUAN Peijiang School of Mechatronic Engineering and Automation Shanghai University School of Mechanical Engineering and Automation Beihang University

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.

关键词： quadruped robot trot gait trajectory planning dynamic modeling energy efficiency

Kinematic mechanism and path planning of the Essboard

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Science China(Technological Sciences) 2013年第6期56卷 1499-1516页

作者： SU BaiQuan wang tianmiao wang JunChen KUANG ShaoLong School of Mechanical Engineering and Automation Beijing University of Aeronautics and Astronautics School of Engineering University of Tokyo

In this paper, we study the kinematic mechanism and path planning for a two-caster nonholonomic vehicle (the Essboard) which is a recent variant of skateboard. Different from the most studied Snakeboard, the Essboard consists of a torsion bar and two platforms, each of which contains a pedal and a caster. We first investigate the relationship between the tilt angles of the pedals and the wheel directions of the casters. This relationship reveals how to control the wheel directions by adjusting the tilt angles. Next, the rotational radius of the Essboard is derived for a given pair of tilt angles of both pedals. The rotational radius of the Essboard is much different than that of the Snakeboard. Then we develop a path-planning algorithm for the Essboard to move from a start position to the goal, using a series of consecutively connected arcs, which are tangent to each other at the connected points. It is shown from a kinematic point of view that the path planning of the Essboard can be solved by a series of pairs of pedals' tilt angles. Three experiments are conducted to confirm the correctness of the main results. The results in this paper are a foundation for further study of the Essboard.

关键词： mobile robot path planning nonholonomic system rolling motion point-to-point maneuver

New design of a compact aero-robotic drilling end effector: An experimental analysis

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Chinese Journal of Aeronautics 2016年第4期29卷 1132-1141页

作者： Shi Zhenyun Yuan Peijiang wang Qishen Chen Dongdong wang tianmiao School of Mechanical Engineering and Automation Beihang University Beijing Institute of Aerospace Control Devices

This paper presents the development of a normal adjustment cell (NAC) in aero-robotic drilling to improve the quality of vertical drilling, by using an intelligent double-eccentric disk normal adjustment mechanism (2-EDNA), a spherical plain bearing and a floating compress module with sensors. After the surface normal vector is calculated based on the laser sensors' feedback, the 2-EDNA concept is conceived specifically to address the deviation of the spindle from the surface normal at the drilling point. Following the angle calculation, depending on the actual initial position, two precise eccentric disks (PEDs) with an identical eccentric radius are used to rotate with the appropriate angles using two high-resolution DC servomotors. The two PEDs will carry the spindle to coincide with the surface normal, keeping the vertex of the drill bit still to avoid repeated adjustment and position compensation. A series of experiments was conducted on an aeronautical drilling robot platform with a precise NAC. The effect of normal adjustment on bore diameter, drilling force, burr size, drilling heat, and tool wear was analyzed. The results validate that using the NAC in robotic drilling results in greatly improved vertical drilling quality and is attainable in terms of intelligence and accuracy. (C) 2015 The Authors. Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics.

关键词： Drilling robot Eccentric disk Normal adaptive Normal adjustment cell Surface normals

On the thrust performance of an ionic polymer-metal composite actuated robotic fish: Modeling and experimental investigation

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Science China(Technological Sciences) 2012年第12期55卷 3359-3369页

作者： wang tianmiao SHEN Qi WEN Li LIANG JianHong Robotic Institute School of Mechanical Engineering and AutomationBeihang UniversityBeijing 100191China Museum of Comparative Biology Harvard University26 Oxford St.CambridgeMA 02138USA

In this paper, we theoretically predict and experimentally measure the thrust efficiency of a biomimetic robotic fish, which is propelled by an ionic polymer-metal composite （IPMC） actuator. A physics-based model that consists of IPMC dynamics and hydrodynamics was proposed, and simulation was conducted. In order to test the thrust performance of the robotic fish, a novel experimental apparatus was developed for hydrodynamic experiments. Under a servo towing system, the IPMC fish swam at a self-propelled speed where external force is averagely zero. Experimental results demonstrated that the theoretical model can well predict the thrust efficiency of the robotic fish. A maximum thrust efficiency of 2.3x10-3 at 1 Hz was recorded experi- mentally, the maximum thrust force was 0.0253 N, recorded at 1.2 Hz, while the maximum speed was 0.021 m/s, recorded at 1.5 Hz, and a peak power of 0.36 W was recorded at 2.6 Hz. Additionally, the optimal actuation frequency for the thrust efficiency was also recorded at the maximum self-propelled speed. The present method of examining the thrust efficiency may also be applied to the studies of other types of smart material actuated underwater robots.

关键词： biomimetic robotic fish hydrodynamic modeling thrust efficiency measurement ionic polymer-metal composites

Algorithm for Smooth S-curve Feedrate Profiling Generation

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Chinese Journal of Mechanical Engineering 2011年第2期24卷 237-247页

作者： CHEN Youdong WEI Hongxing SUN Kai LIU Miao wang tianmiao School of Mechanical Engineering and Automation Beihang University Beijing 100191 China

The algorithms for feedrate profile generation,such as linear and S-curve profiles,have been widely used in machinery controllers,and these algorithms can greatly improve the smoothness of ***,most of the algorithms lead to the discontinuous acceleration/deceleration and jerk,or high jerk levels,which is very harmful to machine tool or robot in most occasions. This paper presents a smooth S-curve feedrate profiling generation algorithm that produces continuous feedrate,acceleration,and jerk *** jerk is obtained by imposing limits on the first and second time derivatives of acceleration,resulting in trapezoidal jerk profiles along the tool *** discretization of smooth S-curve feedrate is realized with a novel approach that improves the efficiency without calculating the deceleration point in each sampled *** ensure that the interpolation time is a multiple of the value of sampled time,the feedrate,acceleration,jerk,and jerk derivative are ***,to improve the efficiency,the interpolation steps of all regions are computed before *** to the distance of trajectory,the smooth S-curve acceleration and decelerations are divided into three blocks：normal block,short block type-Ⅰ,and short block type-Ⅱ.Finally feedrate discretization of short block type-Ⅰand type-Ⅱis obtained with considering the *** proposed generation algorithm is tested in machining a part on a five axis milling machine,which is controlled with the CNC system for newly developed high-speed machine *** test result shows that the smooth S-curve approach has the smoother feedrate,acceleration,deceleration,and jerk profiles than *** proposed algorithm ensures the automated machinery motion smoothness,and improves the quality and efficiency of the automated machinery motion planning.

关键词： S-curve acceleration/deceleration feedrate control computer numerical control(CNC)

Mobile Robot Control Based on Dynamic Potential

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Journal of Systems Engineering and Electronics 1992年第1期3卷 73-82页

作者： tianmiao, wang Bo, Zhang Zengren, Yuan Kezhong, He Tsnghua Univ Beijing China

An efficient method is presented for implementing mobile robot perception-action behaviors, based on time varying environment potential field approach. First, in this paper, the concept of dynamic potential U(x,y,z,t) is proposed for representing the environment of a mobile robot, and the form of U(x,y,z,t) is deduced, and then the velocity control of the vehicle with two wheel is directly calculated by transition function T of U(x,y,z,t). Finally, the perception-action layer is successfully implemented for avoiding collision, wandering, and integrating path planning and steering control on THMR-II (tsingHua university Mobile Robot system). Based on sonar array signals, the experimental results are given to show that THMR-II has better reflexive function, real-time obstacle avoidance, adaptability and robustness for complex environments.

关键词： Control systems Sensory perception Time varying systems Velocity control

Cormorant Webbed-feet Support Water-surface Takeoff:Quantitative Analysis via CFD

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Journal of Bionic Engineering 2021年第5期18卷 1086-1100页

作者： Jinguo Huang Jianhong Liang Xingbang Yang Hongyu Chen tianmiao wang Robotics Institute Beihang UniversityBeijing 100083China Institute of Micro Technology and Medical Device Technology Technical University of Munich85748 GarchingGermany Media Lab Massachusetts Institute of TechnologyCambridgeMA 02139-4307USA

The bio-inspired aerial–aquatic vehicle off ers attractive perspectives for future intelligent robotic ***’s webbed-feet support water-surface takeoff is a typical locomotion pattern of amphibious water birds,but its highly maneuverable and agile kinetic behaviors are inconvenient to measure directly and challenging to calculate *** paper presents a numerical Computational Fluid Dynamic(CFD)technique to simulate and reproduce the cormorant's surface takeoff process by modeling the three-dimensional biomimetic *** numerical analysis of the fluid flows and hydrodynamic forces around a cormorant’s webbed feet,body,and wings are conducted,which are consistent with experimental results and theoretical *** results show that the webbed feet indeed produced a large majority of the takeoff power during the initial takeoff *** lift and greater angle of attack are generated to bring the body off the water as soon as *** the discussion of the mechanism of the cormorant’s water-surface takeoff and the relevant characteristics of biology,the impetus and attitude adjustment strategies of the aerial–aquatic vehicle in the takeoff process are illustrated.

关键词： Aerial-aquatic vehicle Cormorant’s takeoff Quantitative hydrodynamic analysis Computational Fluid Dynamics(CFD) Multiphase flow Bionic prototype verification