Scale effect mechanism research of insect-imitating hexapod robot

Yiqun Liu,Hao Li,Jianfeng Wang,Liang Ding,Tao Liu,Haibo Gao 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.6

The scale parameter is one of the key factors which influence the structure and locomotion characteristics of the legged robot. The scale effect mechanism of animals in nature was revealed, and the influence of scale parameters on animal was analyzed. This paper establishes a dynamic model of insect-imitating hexapod robot. A high-fidelity simulation platform for hexapod robot was established based on Vortex, and the foot-ground interaction mechanics model was established and applied to the developed simulation platform. Based on the existing six-legged robot prototype, the validity of the relevant model and the fidelity of the simulation platform are verified. The influence of a robot’s mass and characteristic size on its feature locomotion was analyzed. The foot force rises with the increase of the whole robot mass, and the foot force of the unit robot mass decreases with the increase of the whole robot mass, eventually tending to a fixed value. The maximum joint torque rises with the increase of the whole robot mass. The system power rises with the increase of the whole robot mass, but the system power of unit robot mass is basically a constant value. The peak system power decreases with the increase of the distance between the front and the rear leg, and the joint torque rises with the increase of the distance between the front and rear leg. The related research results have guiding significance and reference value for the system design of hexapod robots.

Comparative study on the reachable workspaces of regular and irregular axially symmetric hexapod robots

Aditya Srinivas Manohar,Shravan Anand Komakula,Kalaiarassan Gunasekaran,Padmanabhan Panchu K 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.10

Six-legged hexapod walking robots are well-known for their intrinsic stability during navigation and 6-DoF object manipulation. The robot must be operated under a stable workspace envelope to attain effective manipulation. The structural parameters of the robot dramatically influence the characteristics of the workspace. Most studies analyze the workspace only by varying the leg parameter of the robot, maintaining the base configuration constant. This study aims to investigate the effect of change in the base plate characteristics on the workspace for an axially symmetric hexapod robot with cyclic and elliptical configurations. Superimposing the lateral 2D workspace of each pair of legs evolved to obtain a 3D workspace. The quantitative data analysis of the workspace shows that the cyclic configuration has an average increase of 23.74 %, and the elliptical configuration has a reduction of 1.97 % reachable workspace volume compared with regular hexapods. Furthermore, regular, cyclic, and elliptical hexapods are fabricated and validated with the selective workspace analysis data to reinforce the results. This study shows that the change in the hexagonal base plate configuration has a significant influence on workspace characteristics.

Hexapod robot의 시뮬레이션 기반 동역학 및 제어 설계

권정주(Jeong Joo Kwon),오영교(Young Kyo Oh),김성수(Sung-Soo Kim),원문철(Moon cheol Won),박성호(Sung ho Park) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

In order to test a camera stabilizer system mounted on a unmanned vehicle or a mobile robot in the laboratory environment, a hexapod robot that can generate vehicle motion is being developed. Simulation based design procedure has been employed for the development of the hexapod robot system. A virtual model of the hexapod robot has been created using 3D CAD modeler ProE and multibody dynamics program ADAMS. The required motor capacity has been estimated by inverse dynamics analysis of the virtual model to select motors. Motor modeling of the selected motor has been carried out with actual motor test. Transfer function of the motor has been obtained for the virtaul model. Dynamics and control co-simulations using ADAMS and Matlab/Simulink have been carried out to evaluate the control performances. Gain tuning process has been carried out with this virtual model to show the effectiveness of the simulation based design.

Mobility properties analyses of a wall climbing hexapod robot

Bin He,Shoulin Xu,Yanmin Zhou,Zhipeng Wang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.3

In this paper, we investigate the Degree of freedom (DOF), workspace and singularity of a wall climbing hexapod robot. The robot has two typical working modes, which are the six or three legs attaching on the wall, so robot can be regarded as 6SRRR or 3SRRR parallel mechanism, respectively. First, the DOF of the robot is analyzed by the screw theory. The result indicates that two configurations of the robot possess 6-DOF, and the screw theory makes the calculation of the DOF become extremely simple. Moreover, the workspace of the robot body is studied with constraint equations, which obtains the influence of structural parameters on workspace. After that, a new simple Jacobian matrix is proposed to analyze the singularity, and obtain the singular configurations of the robot, which greatly simplifies the calculation of Jacobian matrix of the robot. Finally, by experiments to verify that the singularity analysis method is correct. The singularity analysis of this paper could be applied for effective control of the robot to avoid singular configurations.

State estimation of a heavy-duty hexapod robot with passive compliant ankles based on the leg kinematics and IMU data fusion

Yufei Liu,Haibo Gao,Liang Ding,Guangjun Liu,Zongquan Deng,Nan Li 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.8

To control autonomous walking of a legged robot, it is essential to obtain the instantaneous velocity and posture of the robot. This paper presents a full body state estimation algorithm for a hexapod robot to estimate the velocity and posture of the trunk body without geometric knowledge of the environment. The velocity and posture estimates of the hexapod robot with passive compliant ankles are further processed by a data fusion method that is proposed based on the extended Kalman filter (EKF) technique, utilizing the leg kinematics model of the robot and the readouts from an on–board inertial measurement unit (IMU). The absolute footholds of the hexapod robot are estimated together with the velocity and posture of the trunk body, with consideration of intermittent ground contacts. Experiments have been conducted on both flat and uneven terrains, and the results have confirmed the effectiveness of the proposed approach.

Multiple-degrees-of-freedom dielectric elastomer actuators for soft printable hexapod robot

Nguyen, Canh Toan,Phung, Hoa,Nguyen, Tien Dat,Jung, Hosang,Choi, Hyouk Ryeol Elsevier 2017 Sensors and actuators. A Physical Vol.267 No.-

<P><B>Abstract</B></P> <P>In this paper, we present the development of a printable hexapod walking robot driven by the multiple-degrees-of-freedom (multi-DOF) soft actuators based on dielectric elastomer. The multi-DOF soft actuators are employed to provide versatile movements including two translations and single rotation within a simple structure based on the antagonistic configuration of two elastomer membranes. The soft actuators demonstrate the potential of being used as a multifunctional joint to actuate the robot leg’s motion which biologically mimics the animal’s walking posture. The actuator performances are enhanced by developing the novel mixed silicone compound, Wacker P7670 and Nusil CF2-2186, and applying the optimized prestrain to the silicone-based actuator membranes. A theoretically and experimentally comprehensive study was carried out to investigate the soft actuators performances in terms of linear displacements, deflection angle, output force, torque, dynamic response, and load carrying capability. We successfully demonstrated the robot’s locomotion on the flat rigid surfaces with the forward and backward walking movements at an average speed of 3cm/s (about 12 body-lengths/min) using the alternating tripod walking gait of insects.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The application of the multiple-degrees-of-freedom (multi-DOF) soft actuators based on dielectric elastomer in driving the locomotion of a hexapod walking robot is presented in this paper. </LI> <LI> The actuator performances are significantly enhanced by replacing the synthetic elastomer with the novel mixed silicone compound, Wacker P7670 and Nusil CF2-2186, and applying the optimized prestrain to the silicone-based actuator membranes. </LI> <LI> The hexapod robot’s fabrication process is implemented using 3D printing technology which provides the lightweight, scalable, and easy-to-manufacture characteristic of the robot. </LI> <LI> A theoretically and experimentally comprehensive study is carried out to investigate the soft actuators performances in terms of linear displacements, deflection angle, output force, torque, dynamic response, and load carrying capability. </LI> <LI> The hexapod robot’s locomotion on flat rigid surfaces with the forward and backward walking movements at an average speed of 3cm/s (about 12 body-lengths/min) using the alternating tripod walking gait of insects is successfully demonstrated. </LI> </UL> </P>

Influence of hexapod robot foot shape on sinking considering multibody dynamics

Gang He,Zhaoyuan Cao,Qian Li,Denglin Zhu,Ji Aimin 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.9

Hexapod robots have attracted attention for their excellent terrain adaptabilities. When a robot walks on soft soil, dynamic subsidence and slippage greatly reduce its walking performance. The influence of foot’s shape is usually ignored or simply studied without considering the multibody dynamics of the robot. This study is focused on the influence of the foot shape on the walking performance of a robot by coupling the sinkage with multibody dynamics. A composite contact model based on the Bekker, spring-damping, and Janosi– Hanamoto models was used to model the interaction of the robot and soft soil. Non-uniform rational B-spline (NURBS) surface and mesh were used to describe the geometries of foot and soft soil, respectively. The influences of three foot shapes on the sinkage and walking stability of the robot were analyzed by comparsion. The improved X-shaped foot reduced the robot’s sinkage and improved its walking stability.

Motion planning and simulation verification of a hydraulic hexapod robot based on reducing energy/flow consumption

Zongquan Deng,Yiqun Liu,Liang Ding,Haibo Gao,Haitao Yu,Zhen Liu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

Minimizing the energy and flow consumption is significant to realize the locomotion of a hydraulically actuated hexapod robot formobile field applications. This paper proposes a low energy cost foot trajectory planning method to realize a constant velocity of the bodyand optimize the power and flow consumption of a hexapod robot. A dephased gait generating method is also proposed to decrease theflow demand. A simulation platform for hexapod robots was developed using C++ and based on the vortex physics engine. Power andflow consumption models were derived to verify the proposed methods. The simulation platform was used to verify the effectiveness ofthe proposed methods at optimizing the power and flow consumption.

곤충 모방 등반 로봇의 기구학

압둘 유마랸토(Abdul A. Yumaryanto),안재범(Jaebum An),이상윤(Sangyoon Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

In this paper, we design a model of hexapod robot inspired by six-legged insects which able to climb multiple stairs. Legged robots are used to overcome limitations that wheeled ones have. The ability to climb and traverse an uneven terrain with a good stability in both static and dynamic situations is the main reason why we use six-legged insects as an inspiration of our kinematic design for leg robot. From the experiments using high-speed camera we analyze how the cockroach climbs multiple stair-like obstacles and how each leg of climbing cockroach has its own function. Our result is the design of a six-legged robot with two degrees of freedom in each leg, which enable the rotational and translational motion. To visualize and analyze how it can climb the stairs we also present a simulation using the ADAMS software.

LIPCA 작동기를 이용한 곤충모방로봇

압둘 아지스,안재범,이상윤 건국대학교 산업기술연구원 2006 건국기술연구논문지 Vol.31 No.-

In this paper we present the design and prototype of a six-legged walking robot which uses Lightweight Piezoceramic Composite curved Actuator (LIPCA) as its actuator. LIPCA consists of multiple layers of glass/epoxy and carbon/epoxy that encapsulate a unimorph piezoelectric ceramic actuator. It uses lightweight fiber-reinforced plastic layers and it generates a higher force and a larger displacement than other conventional piezo-composite type actuators. Like most six-legged walking insects including cockroaches, our robot uses the alternating tripod gait where the front and rear legs on the same side move together with the middle leg on the other side for its locomotion. Two LIPCA strips in different phases are used for actuating each tripod so that only one tripod can touch the ground. All the experiments with the prototype show that LIPCA can be used as an alternative actuator for small and light mobile robots.