Development of an Insect-Inspired Hexapod Robot Actuated by Soft Actuators

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Canh Toan Nguyen ◽  
Hoa Phung ◽  
Phi Tien Hoang ◽  
Tien Dat Nguyen ◽  
Hosang Jung ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Simple Structure ◽  
Walking Speed ◽  
Hexapod Robot ◽  
Actuation Frequency ◽  
Compact Structure ◽  
Tripod Gait ◽  
Soft Actuators ◽  
Rigid Surfaces ◽  
Walking Locomotion

Insects are one of the most diverse group of animals on the planet and are almost ubiquitous. Their walking locomotion has inspired engineers and provided effective solutions for designing transport methods for legged robots. In this paper, we introduce a hexapod walking robot that mimics the design and walking motions of insects. The robot is characterized by small size, light weight, simple structure, and considerably fast walking speed. Three pairs of its legs are driven by three five-degrees-of-freedom (5DOF) soft actuators based on dielectric elastomer (DE) actuators which can provide up to five movements (including three translations and two rotations) within a compact structure. The robot imitates the crawling motion of an insect using the alternating tripod gait. The experiments show that the robot can achieve an average walking speed of 5.2 cm/s (approximately 21 body-lengths per minute) at 7 Hz of actuation frequency on flat rigid surfaces. Furthermore, the robot also demonstrates the omnidirectional capabilities of walking sideways and rotating its body direction, which enhance the potential of applying the proposed robot in practical uses.

scholarly journals Fault-Tolerant Tripod Gait Planning and Verification of a Hexapod Robot

2020 ◽  
Vol 10 (8) ◽  
pp. 2959
Author(s):  
Yiqun Liu ◽  
Xuanxia Fan ◽  
Liang Ding ◽  
Jianfeng Wang ◽  
Tao Liu ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Fault Tolerant ◽  
Kinematic Model ◽  
Stability Margin ◽  
The Body ◽  
Hexapod Robot ◽  
Gait Planning ◽  
Phase Sequence ◽  
Gait Phase ◽  
Tripod Gait

In some hazardous or inaccessible applications, such as earthquake rescue, as a substitute for mankind, robots are expected to perform missions reliably. Unfortunately, the failure of components is difficult to avoid due to the complexity of robot composition and the interference of the environment. Thus, improving the reliability of robots is a crucial problem. The hexapod robot has redundant degrees of freedom due to its multiple joints, making it possible to tolerate the failure of one leg. In this paper, the Fault-Tolerant Tripod (F-TT) gait dealing with the failure of one leg is researched. The Denavit–Hartenberg (D-H) method is exploited to establish a kinematic model for the hexapod robot, the Jacobian matrix is analyzed, and it is proved that the body can be controlled when three legs are supported. Then, an F-TT gait phase sequence planning method based on a stability margin is established, and a method to improve stability is proposed. The trajectory for the center of gravity (COG) and foot is studied. Finally, a simulation model and prototype robot experiments are developed, and the effectiveness of the proposed method is verified.

scholarly journals Design and Analysis of a Tendon-driven Snake-arm Robot Based on Spherical Magnet

2021 ◽  
Author(s):  
Bei Liu ◽  
Lairong Yin ◽  
Long Huang ◽  
Peng Zhang ◽  
Kefu Yi
Keyword(s):  
Degrees Of Freedom ◽  
Simple Structure ◽  
Kinematic Model ◽  
Lateral Force ◽  
Compact Structure ◽  
Multiple Degrees Of Freedom ◽  
Opposite Pole ◽  
Passive Compliance

The tendon-driven snake-arm robot can achieve multiple degrees of freedom (DOF) bending motion with a compact structure, which enables the robot to be widely applied in confined environments. However, if a conventional tendon-driven snake-arm robot is subject to a lateral force on the distal end, it will experience passive compliance. In this paper, a 2-DOF rolling joint is proposed based on the opposite-pole attraction of spherical magnets, which has a relatively simple structure than traditional joints. By serial connecting the 2-DOF rolling joints, a novel snake-arm robot is designed utilizing a tendon-driven approach. The kinematic model and workspace of the snake-arm robot are obtained, and the bending motion is validated. Based on the kinematic model, it is theoretically proved that the proposed robot can avoid passive compliance. In addition, this feature is verified through load experiments on the developed prototype.

PD Controller With Self Adaptive Gains for Quadrotor Waypoint Navigation

2020 ◽  
Author(s):  
Madhavan Sudakar ◽  
Siddharth Sridhar ◽  
Manish Kumar
Keyword(s):  
Control Algorithm ◽  
Degrees Of Freedom ◽  
Simple Structure ◽  
Reference Model ◽  
Pd Controller ◽  
Lyapunov Stability Analysis ◽  
Waypoint Navigation ◽  
Novel Method ◽  
Model Reference Adaptive ◽  
Random Gain

Abstract Proportional-Derivative (PD) controllers are commonly used in quadrotors due to their simple structure. Tuning of the gains of the PD controller is often cumbersome due to strong coupling of the dynamics between three linear and three angular degrees of freedom. This paper presents a novel method of auto adjusting the proportional and derivative gains of the quadrotor without the use of any stable reference model (unlike model reference adaptive control). The gains are automatically adjusted throughout the flight based on just the state errors. Lyapunov stability analysis and adaptive gain law is used to formulate the control algorithm to achieve way point navigation. It is shown that our proposed controller achieves effective way point navigation even when started off from random gain values.

Two-Point Floating Clamping Device Based on Fixed Cylinder with Double-Piston and Toggle-Lever Force Amplifier

2011 ◽  
Vol 201-203 ◽  
pp. 2220-2223 ◽  
Author(s):  
Guang Ju Si ◽  
Kang Min Zhong ◽  
Jun Peng Jia
Keyword(s):  
Degrees Of Freedom ◽  
Clamping Force ◽  
Compact Structure ◽  
Mechanical Calculation ◽  
Working Principle ◽  
Working Status ◽  
Clamping Device ◽  
Fixed Cylinder ◽  
Vibration Noise

Two-point floating clamping device, widely used in manufacturing field, can effectively ensure the same clamping force on different workpieces or different surfaces in one workpiece. But due to the application of unitary suspended articulated cylinder, traditional two-point floating devices have disadvantages such as poor working status, great impaction, vibration and noise. A kind of innovatively designed two-point floating clamping devices, with rigidly fixed cylinder replacing unitary suspended articulated cylinder, is presented in this paper. To solve the problem of insufficient degrees of freedom, three different methods are applied. This device has significant advantages in compact structure, small impaction and vibration noise. Moreover, the working principle and mechanical calculation formulas are presented in this paper, which is instructive to the industrial field.

scholarly journals Kinematic Strategies in Newly Walking Toddlers Stepping Over Different Support Surfaces

2010 ◽  
Vol 103 (3) ◽  
pp. 1673-1684 ◽  
Author(s):  
Nadia Dominici ◽  
Yuri P. Ivanenko ◽  
Germana Cappellini ◽  
Maria Luisa Zampagni ◽  
Francesco Lacquaniti
Keyword(s):  
Degrees Of Freedom ◽  
Walking Speed ◽  
Search Space ◽  
Systematic Change ◽  
Support Surface ◽  
Coordination Pattern ◽  
Surface Conditions ◽  
Surface Inclination ◽  
Support Surfaces ◽  
Inclined Surface

In adults, locomotor movements are accommodated to various support surface conditions by means of specific anticipatory locomotor adjustments and changes in the intersegmental coordination. Here we studied the kinematic strategies of toddlers at the onset of independent walking when negotiating various support surface conditions: stepping over an obstacle, walking on an inclined surface, and on a staircase. Generally, toddlers could perform these tasks only when supported by the arm. They exhibited strategies very different from those of the adults. Although adults maintained walking speed roughly constant, toddlers markedly accelerated when walking downhill or downstairs and decelerated when walking uphill or upstairs. Their coordination pattern of thigh–shank–foot elevation angles exhibited greater inter-trial variability than that in adults, but it did not undergo the systematic change as a function of task that was present in adults. Thus the intersegmental covariance plane rotated across tasks in adults, whereas its orientation remained roughly constant in toddlers. In contrast with the adults, the toddlers often tended to place the foot onto the obstacle or across the edges of the stairs. We interpret such foot placements as part of a haptic exploratory repertoire and we argue that the maintenance of a roughly constant planar covariance—irrespective of the surface inclination and height—may be functional to the exploratory behavior. The latter notion is consistent with the hypothesis proposed decades ago by Bernstein that, when humans start to learn a skill, they may restrict the number of degrees of freedom to reduce the size of the search space and simplify the coordination.

scholarly journals Analysis and research of quadruped robot’s legs: A comprehensive review

2019 ◽  
Vol 16 (3) ◽  
pp. 172988141984414 ◽  
Author(s):  
Yuhai Zhong ◽  
Runxiao Wang ◽  
Huashan Feng ◽  
Yasheng Chen
Keyword(s):  
Degrees Of Freedom ◽  
Walking Speed ◽  
Load Capacity ◽  
Basic Component ◽  
Application Performance ◽  
Comprehensive Review ◽  
Research Results ◽  
The Core ◽  
Quadruped Robots ◽  
Job Adaptability

As an important basic component of quadruped robots, mechanical legs provide the robots with excellent maneuverability and versatility, which determine the core application performance such as job adaptability, walking speed, and load capacity. A large number of robotics institutes for the last few decades have studied mechanical legs used by quadruped robots and published many research results. In this article, we collect these research results and classify them into three categories (prismatic legs, articulated legs, and redundant articulated legs) according to the degrees of freedom and then introduce and analyze them. On this basis, we summarize and study the design methods of the actuators and mechanical leg structures. Finally, we make some suggestions for the development of quadruped robot’s legs in the future. The motivation of this review is to summarize and analyze previous research efforts and provide useful guidance for future robotic designers to develop more efficient mechanical legs of quadruped robots.

scholarly journals Recent Developments on Modeling for a 3-DOF Micro-Hand Based on AI Methods

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 792
Author(s):  
Shuhei Kawamura ◽  
Mingcong Deng
Keyword(s):  
Artificial Intelligence ◽  
Degrees Of Freedom ◽  
Air Pressure ◽  
Support Vector ◽  
Input Output ◽  
Soft Actuator ◽  
Flexible Materials ◽  
Recent Developments ◽  
Soft Actuators ◽  
Three Degrees Of Freedom

Recently, soft actuators have been expected to have many applications in various fields. Most of the actuators are composed of flexible materials and driven by air pressure. The 3-DOF micro-hand, which is a kind of soft actuator, can realize a three degrees of freedom motion by changing the applied air pressure pattern. However, the input–output relation is nonlinear and complicated. In previous research, a model of the micro-hand was proposed, but an error between the model and the experimental results was large. In this paper, modeling for the micro-hand is proposed by using multi-output support vector regression (MSVR) and ant colony optimization (ACO), which is one of the artificial intelligence (AI) methods. MSVR estimates the input–output relation of the micro-hand. ACO optimizes the parameters of the MSVR model.

scholarly journals Modeling and System Integration for a Thin Pneumatic Rubber 3-DOF Actuator

Actuators ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 32 ◽  
Author(s):  
Shuhei Kawamura ◽  
Mizuki Sudani ◽  
Mingcong Deng ◽  
Yuichi Noge ◽  
Shuichi Wakimoto
Keyword(s):  
System Integration ◽  
Degrees Of Freedom ◽  
Small Diameter ◽  
Experimental System ◽  
Longitudinal Direction ◽  
Axial Direction ◽  
Artificial Muscles ◽  
Contraction Force ◽  
Proposed Model ◽  
Soft Actuators

Recently, soft actuators have been getting increased attention within various fields. The actuators are composed of flexible materials and driven by pneumatic pressure. A thin pneumatic rubber actuator generating 3 degrees of freedom motion, called 3-DOF micro-hand, has small diameter McKibben artificial muscles which generate a contraction force in the axial direction. By this structure, the micro-hand contracts in the longitudinal direction and bends in any direction by changing the applied air pressure pattern to the artificial muscles. The input–output relation of the micro-hand, however, is complicated and has not been modeled. In this paper, modeling for 3-DOF micro-hand is proposed. Moreover, the experimental system is built for the micro-hand and the proposed model is evaluated by using the experimental results.

scholarly journals Conceptual mechanical design of antagonistic variable stiffness joint based on equivalent quadratic torsion spring

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042094129
Author(s):  
Jishu Guo
Keyword(s):  
Degrees Of Freedom ◽  
Modular Design ◽  
Angular Displacement ◽  
Variable Stiffness ◽  
Human Robot Interaction ◽  
Design Calculation ◽  
Robot Arm ◽  
Compact Structure ◽  
Torsion Spring ◽  
Stiffness Characteristics

The variable stiffness joint is a kind of flexible actuator with variable stiffness characteristics suitable for physical human–robot interaction applications. In the existing variable stiffness joints, the antagonistic variable stiffness joint has the advantages of simple implementation of variable stiffness mechanism and easy modular design of the nonlinear elastic element. The variable stiffness characteristics of antagonistic variable stiffness joints are realized by the antagonistic actuation of two nonlinear springs. A novel design scheme of the equivalent nonlinear torsion spring with compact structure, large angular displacement range, and desired stiffness characteristics is presented in this article. The design calculation for the equivalent quadratic torsion spring is given as an example, and the actuation characteristics of the antagonistic variable stiffness joint based on the equivalent quadratic torsion spring are illustrated. Based on the design idea of constructing the antagonistic variable stiffness joint with compact structure and high compliance, as well as the different design requirements of the joints at different positions of the multi–degrees of freedom robot arm, nine types of mechanical schemes of antagonistic variable stiffness joint with the open design concept are proposed in this article. Finally, the conceptual joint configuration schemes of the robot arm based on the antagonistic variable stiffness joint show the application scheme of the designed antagonistic variable stiffness joint in the multi–degrees of freedom robot.

Real-Time Online Feet Trajectory Generation Method for Hexapod Robot

2015 ◽  
Vol 220-221 ◽  
pp. 148-152
Author(s):  
Tomas Luneckas ◽  
Mindaugas Luneckas ◽  
Dainius Udris
Keyword(s):  
Real Time ◽  
Degrees Of Freedom ◽  
Trajectory Generation ◽  
Electromechanical System ◽  
Hexapod Robot ◽  
Walking Robot

Hexapod walking robot is a complex electromechanical system with many degrees of freedom. Six legs ensure robot’s stability as at least three legs are always on the ground but require more effort in order to synchronize them for a successful locomotion. In this paper, we present a method that allows calculate feet trajectories in real-time and online. This method enables to select different gaits and their parameters.

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