Crab-inspired compliant leg design method for adaptive locomotion of a multi-legged robot

2021 ◽  
Author(s):  
Jun Zhang ◽  
Qi Liu ◽  
Jingsong Zhou ◽  
Aiguo Song
Keyword(s):  
High Speed ◽  
Design Method ◽  
Spring Steel ◽  
Thin Wall ◽  
Legged Robot ◽  
Kinematic Modeling ◽  
Body Frame ◽  
Dynamic Simulations ◽  
Mitten Crab ◽  
Leg Design

Abstract Chinese mitten crab has unique limb structures composed of a hard exoskeleton and flexible muscles. They enable the crab to locomote adaptively and safely on various terrains. In this work, we investigated the limb structures, motion principle, and gaits of the crab using a high-speed camera and a press machine. Then, a novel compliant robot leg design method is proposed, inspired by the crab limb. The leg comprises six hard scleromeres and a flexible thin-wall spring steel sheet (FSSS) mimicking the exoskeleton and muscle. The scleromeres connected one by one with rotational joints are designed with slots. The front end of the FSSS is fixed on the scleromere close to the ground. The rear end crosses the slots and is mounted at the shaft of a linear actuator installed at the rear scleromere. The leg bends and stretches when the actuator pushes and pulls the FSSS, respectively. The kinematic modeling, rigid-flexible coupling dynamic simulations, and leg prototype tests are conducted, which verify the leg design approach. Thirdly, we put forward a multi-legged robot with eight compliant legs and design its gait using the gaits of the crab. Finally, the robot’s performance is evaluated, including the capabilities of walking on different terrains at adjustable speeds and body heights, traversing low channels, walking on slopes, and carrying loads. The results prove that the single-motor-actuated compliant legs and their dynamic coupling with the rigid robot body frame can enable them to have the ground clearance ability and realize the adaptive walking of the robot. The leg design methodology can be used to design multi-legged robots with the merits of compact, light, low mechanical complexity, high safety, and easy to control, for many applications, such as environmental monitoring, search and rescue.

A leg design method for high speed quadrupedal locomotion

2017 ◽  
Author(s):  
Spyridon Dallas ◽  
Konstantinos Machairas ◽  
Konstantinos Koutsoukis ◽  
Evangelos Papadopoulos
Keyword(s):  
High Speed ◽  
Design Method ◽  
Quadrupedal Locomotion ◽  
Leg Design

scholarly journals X-ray Determination of Compressive Residual Stresses in Spring Steel Generated by High-Speed Water Quenching

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1154
Author(s):  
Diego E. Lozano ◽  
George E. Totten ◽  
Yaneth Bedolla-Gil ◽  
Martha Guerrero-Mata ◽  
Marcel Carpio ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
High Speed ◽  
Spring Steel ◽  
X Ray Diffraction ◽  
Laboratory Equipment ◽  
X Ray ◽  
Water Chamber ◽  
Hardened Case ◽  
Compressive Residual Stresses

Automotive components manufacturers use the 5160 steel in leaf and coil springs. The industrial heat treatment process consists in austenitizing followed by the oil quenching and tempering process. Typically, compressive residual stresses are induced by shot peening on the surface of automotive springs to bestow compressive residual stresses that improve the fatigue resistance and increase the service life of the parts after heat treatment. In this work, a high-speed quenching was used to achieve compressive residual stresses on the surface of AISI/SAE 5160 steel samples by producing high thermal gradients and interrupting the cooling in order to generate a case-core microstructure. A special laboratory equipment was designed and built, which uses water as the quenching media in a high-speed water chamber. The severity of the cooling was characterized with embedded thermocouples to obtain the cooling curves at different depths from the surface. Samples were cooled for various times to produce different hardened case depths. The microstructure of specimens was observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) was used to estimate the magnitude of residual stresses on the surface of the specimens. Compressive residual stresses at the surface and sub-surface of about −700 MPa were obtained.

Development of High-Speed Response Electromagnetic Linear Actuator Using for Pneumatic Control Valve

2014 ◽  
Vol 532 ◽  
pp. 41-45 ◽  
Author(s):  
Myung Jin Chung
Keyword(s):  
Optimal Design ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Design Method ◽  
Control Valve ◽  
Design Parameters ◽  
Linear Actuator ◽  
Analytic Model ◽  
Electromagnetic Linear Actuator ◽  
Quadratic Programming Method

Analytic model of electromagnetic linear actuator in the function of electric and geometric parameters is proposed and the effects of the design parameters on the dynamic characteristics are analyzed. To improve the dynamic characteristics, optimal design is conducted by applying sequential quadratic programming method to the analytic model. This optimal design method aims to minimize the response time and maximize force efficiency. By this procedure, electromagnetic linear actuator having high-speed characteristics is developed.

scholarly journals Evolution Mechanisms of MgO·Al2O3 Inclusions by Cerium in Spring Steel Used in Fasteners of High-speed Railway

2015 ◽  
Vol 55 (5) ◽  
pp. 970-975 ◽  
Author(s):  
Li Jun Wang ◽  
Yan Qiang Liu ◽  
Qi Wang ◽  
Kuo Chih Chou
Keyword(s):  
High Speed ◽  
Spring Steel ◽  
High Speed Railway

scholarly journals Cockroaches traverse crevices, crawl rapidly in confined spaces, and inspire a soft, legged robot

2016 ◽  
Vol 113 (8) ◽  
pp. E950-E957 ◽  
Author(s):  
Kaushik Jayaram ◽  
Robert J. Full
Keyword(s):  
Body Weight ◽  
High Speed ◽  
Stride Length ◽  
Body Height ◽  
Legged Robot ◽  
Confined Space ◽  
Performance Limits ◽  
Biological Inspiration ◽  
Confined Spaces ◽  
Postural Changes

Jointed exoskeletons permit rapid appendage-driven locomotion but retain the soft-bodied, shape-changing ability to explore confined environments. We challenged cockroaches with horizontal crevices smaller than a quarter of their standing body height. Cockroaches rapidly traversed crevices in 300–800 ms by compressing their body 40–60%. High-speed videography revealed crevice negotiation to be a complex, discontinuous maneuver. After traversing horizontal crevices to enter a vertically confined space, cockroaches crawled at velocities approaching 60 cm⋅s−1, despite body compression and postural changes. Running velocity, stride length, and stride period only decreased at the smallest crevice height (4 mm), whereas slipping and the probability of zigzag paths increased. To explain confined-space running performance limits, we altered ceiling and ground friction. Increased ceiling friction decreased velocity by decreasing stride length and increasing slipping. Increased ground friction resulted in velocity and stride length attaining a maximum at intermediate friction levels. These data support a model of an unexplored mode of locomotion—“body-friction legged crawling” with body drag, friction-dominated leg thrust, but no media flow as in air, water, or sand. To define the limits of body compression in confined spaces, we conducted dynamic compressive cycle tests on living animals. Exoskeletal strength allowed cockroaches to withstand forces 300 times body weight when traversing the smallest crevices and up to nearly 900 times body weight without injury. Cockroach exoskeletons provided biological inspiration for the manufacture of an origami-style, soft, legged robot that can locomote rapidly in both open and confined spaces.

Integrated optimal design of a high-speed planar parallel manipulator

2018 ◽  
Vol 233 (9) ◽  
pp. 2976-2990 ◽  
Author(s):  
Zhengsheng Chen ◽  
Minxiu Kong
Keyword(s):  
Optimal Design ◽  
Parallel Manipulator ◽  
High Speed ◽  
Design Method ◽  
Tracking Error ◽  
Dimensional Synthesis ◽  
Tracking Accuracy ◽  
Nsga Ii ◽  
Parameters Tuning ◽  
Planar Parallel Manipulator

To obtain excellent comprehensive performances of the planar parallel manipulator for the high-speed application, an integrated optimal design method, which integrated dimensional synthesis, motors/reducers selection, and control parameters tuning, is proposed, and the 3RRR parallel manipulator was taken as the example. The kinematic and dynamic performances of condition number, velocity index, acceleration capability, and low-order frequency are taken into accounts for the dimensional synthesis. Then, to match motors/reducers parameters and keep an economical cost, the constraint equations and the parameters library are built, and the cost is chosen as one of the optimization objectives. Also, to get high tracking accuracy, the dynamic forward plus proportional–derivative control scheme is introduced, and the tracking error is chosen as one of the optimization objectives. Hence, the optimization model including dimensional synthesis, motors/reducers selection and controller parameters tuning is established, which is solved by the genetic algorithm II (NSGA-II). The result shows that comprehensive performances can be effectively promoted through the proposed integrated optimal design, and the prototype was constructed according to the Pareto-optimal front.

scholarly journals Study on the High-Speed and Close of the UVA Cooperative Formation Controller Design

2018 ◽  
Vol 36 (2) ◽  
pp. 345-352
Author(s):  
Jialong Zhang ◽  
Jianguo Yan ◽  
Pu Zhang ◽  
Xiaoqiao Qi ◽  
Maolong Lü
Keyword(s):  
Dynamic Characteristic ◽  
High Speed ◽  
Controller Design ◽  
Design Method ◽  
Formation Flight ◽  
Unsteady Aerodynamic ◽  
Aerodynamic Model ◽  
Thrust Vector ◽  
The Stability ◽  
Rudder Angle

Aiming at the high-speed flight of the UAVs cooperative formation, when a single UAV has occurred, need to exit the formation flight and be close or super close to form of the formation quickly. A fast close cooperative formation controller design method is proposed to make up for low the fighting robustness, and be shortcomings of timeliness poorly and analyze the dynamic characteristic of UAV formation flight. Taking the external factors known into consideration, setting up for the longitude maneuver of nonlinear thrust vector and unsteady aerodynamic model, according to the formation velocity, flat tail rudder angle and thrust vector and pitch angle velocity for corresponding input commend signals for the controller to research the dynamic characteristic of UAV formation flight. Meanwhile, the formation flight distance error is the convergence to a fixed value, and the stability of the cooperative formation flight is good. The simulation of results show that the controller can effectively improve the speed of the close or super close to formation, and maintain the stability of the formation flight, which provides a method of the close or super close formation flight controller design.

Machining Evaluation of High-Speed Milling for Thin-Wall Machining of Al7075-T651

2014 ◽  
Vol 541-542 ◽  
pp. 785-791 ◽  
Author(s):  
Joon Young Koo ◽  
Pyeong Ho Kim ◽  
Moon Ho Cho ◽  
Hyuk Kim ◽  
Jeong Kyu Oh ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Integrity ◽  
Cutting Forces ◽  
High Speed ◽  
Surface Condition ◽  
Cutting Conditions ◽  
Depth Of Cut ◽  
Thin Wall ◽  
Machined Surface ◽  
High Speed Milling

This paper presents finite element method (FEM) and experimental analysis on high-speed milling for thin-wall machining of Al7075-T651. Changes in cutting forces, temperature, and chip morphology according to cutting conditions are analyzed using FEM. Results of machining experiments are analyzed in terms of cutting forces and surface integrity such as surface roughness and surface condition. Variables of cutting conditions are feed per tooth, spindle speed, and axial depth of cut. Cutting conditions to improve surface integrity were investigated by analysis on cutting forces and surface roughness, and machined surface condition.

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