scholarly journals Micrometer Positioning Accuracy With a Planar Parallel Continuum Robot

2021 ◽  
Vol 8 ◽  
Author(s):  
Benjamin Mauzé ◽  
Guillaume J. Laurent ◽  
Redwan Dahmouche ◽  
Cédric Clévy
Keyword(s):  
Kinematic Model ◽  
High Accuracy ◽  
Circular Path ◽  
Continuum Robots ◽  
Continuum Robot ◽  
Good Potential ◽  
Proper Estimation ◽  
Articulated Robots ◽  
Automatic Positioning ◽  
Influential Parameters

Parallel Continuum Robots (PCR) have several advantages over classical articulated robots, notably a large workspace, miniaturization capabilities and safe human-robot interactions. However, their low accuracy is still a serious drawback. Indeed, several conditions have to be met for PCR to reach a high accuracy, namely: a repeatable mechanical structure, a correct kinematic model, and a proper estimation of the model’s parameters. In this article, we propose a methodology that allows reaching a micrometer accuracy with a PCR. This approach emphasizes the importance of using a repeatable continuum mechanism, identifying the most influential parameters of an accurate kinematic model of the robot and precisely measuring them. The experimental results show that the proposed approach allows to reach an accuracy of 3.3 µm in position and 0.5 mrad in orientation over a 10 mm long circular path. These results push the current limits of PCR accuracy and make them good potential candidates for high accuracy automatic positioning tasks.

Follow-the-leader motion strategy for multi-section continuum robots based on differential evolution algorithm

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
GuoHua Gao ◽  
Pengyu Wang ◽  
Hao Wang
Keyword(s):  
Differential Evolution ◽  
Kinematic Model ◽  
Differential Evolution Algorithm ◽  
Open Loop ◽  
Continuum Robots ◽  
Content Type ◽  
Loop Control ◽  
Continuum Robot ◽  
Motion Strategy ◽  
The Continuum

Purpose The purpose of this paper is to present a follow-the-leader motion strategy for multi-section continuum robots, which aims to make the robot have the motion ability in a confined environment and avoid a collision. Design/methodology/approach First, the mechanical design of a multi-section continuum robot is introduced and the forward kinematic model is built. After that, the follow-the-leader motion strategy is proposed and the differential evolution (DE) algorithm for calculating optimal posture parameters is presented. Then simulations and experiments are carried out on a series of predefined paths to analyze the performance of the follow-the-leader motion. Findings The follow-the-leader motion can be well performed on the continuum robots this study proposes in this research. The experimental results show that the deviation from the path is less than 9.7% and the tip error is no more than 15.6%. Research limitations/implications Currently, the follow-the-leader motion is affected by the following factors such as gravity and continuum robot design. Furthermore, the position error is not compensated under open-loop control. In future work, this paper will improve the accuracy of the robot and introduce a closed-loop control strategy to improve the motion accuracy. Originality/value The main contribution of this paper is to present an algorithm to generate follow-the-leader motion of the continuum robot based on DE. This method is suitable for solving new arrangements in the process of following a nonlinear path. Then, it is expected to promote the engineering application of the continuum robot.

Jacobian Matrix of a Novel Continuum Robot for Search and Rescue

2013 ◽  
Vol 303-306 ◽  
pp. 1695-1701 ◽  
Author(s):  
Guang Zhu Meng ◽  
Ling Yu Sun ◽  
Ping Peng ◽  
Xian Chun Meng ◽  
Hong Mei Wang ◽  
...  
Keyword(s):  
Jacobian Matrix ◽  
Kinematic Model ◽  
Search And Rescue ◽  
Chain Rule ◽  
Continuum Robots ◽  
Actuation System ◽  
Continuum Robot ◽  
Forward Kinematic

In this paper, a novel continuum robot for search and rescue is presented. A forward kinematic model is derived by product of exponentials formula, compare with conventional D-H method, this method is concise and simplicity. Finally, based on the differential kinematics using the chain rule, the overall Jacobian of the robot is established. This approach can be generally applied to various continuum robots, regardless of the specific actuation system used.

Quasi-static modeling of a novel growing soft-continuum robot

2019 ◽  
pp. 027836491989343
Author(s):  
Cem Tutcu ◽  
Bora A. Baydere ◽  
Seref K. Talas ◽  
Evren Samur
Keyword(s):  
Kinematic Model ◽  
Potential Method ◽  
Static Model ◽  
Model Parameters ◽  
Continuum Robots ◽  
End Effector ◽  
Precise Control ◽  
Proposed Model ◽  
Continuum Robot ◽  
Static Modeling

Soft-continuum robots attract researchers owing to their advantages over rigid-bodied robots such as adaptation of the flexible structure to tortuous environments, and compliant contact mechanics. The need for new modeling methods to attain precise control for such systems has emerged from the recent rapid progress in soft robotics. This article presents a quasi-static model for a growing soft-continuum robot that is propelled via thin-walled inflated tubes, and steered by the difference between tube lengths. Therefore, the robot shaft is modeled as a series of inflated beams under deformation. A quasi-static model coupled with a kinematic model is developed to accurately position the end effector while accounting for the inflated beam stiffness and end-effector loads. The proposed model calculates control parameters, namely tube lengths and tendon tensions required to maintain the end effector at a certain position. Tip deflection due to end-effector loading is calculated and kinematic model inputs are updated to correct positioning error caused by shaft deformation. The model is simulated for the soft-continuum robot moving on a path to show the change in model parameters for various end-effector positions. Results demonstrate the significance of including pressurized tube stiffness in the model for growing robots of similar type. Second, the need for tendons in addition to pneumatic actuation is emphasized for accurate positioning of the end effector under loading. The proposed model offers a potential method for simulation and control of similar growing soft-continuum robots presented in the literature.

Workspace Analysis of Tendon-Driven Continuum Robots Based on Mechanical Interference Identification

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Kun Cao ◽  
Rongjie Kang ◽  
David T. Branson ◽  
Shineng Geng ◽  
Zhibin Song ◽  
...  
Keyword(s):  
Kinematic Model ◽  
Superposition Method ◽  
Continuum Robots ◽  
Bending Angle ◽  
Scanning Method ◽  
Actuation System ◽  
Workspace Analysis ◽  
Continuum Robot ◽  
Mechanical Interference ◽  
Backbone Structure

Continuum robots have excited increasing attention and efforts from the robotic community due to their high dexterity and safety. This paper proposes a design for a type of multimodule continuum robot equipped with an elastic backbone structure and tendon-driven actuation system. The kinematic model of the robot is formulated where the maximum bending angle of a module is obtained by identifying the interference between the backbone structure and the tendons. A superposition method is then used to determine the configuration space of the robotic module. Finally, an approximation method is presented to estimate the workspace of the tendon-driven continuum robot that reduces the computational complexity in comparison with the previously used scanning method. Experiments are provided to validate the proposed methods.

An Origami Parallel Structure Integrated Deployable Continuum Robot

2015 ◽  
Author(s):  
Ketao Zhang ◽  
Chen Qiu ◽  
Jian S. Dai
Keyword(s):  
Translational Motion ◽  
Kinematic Model ◽  
Parallel Structure ◽  
Continuum Robots ◽  
Helical Springs ◽  
Parallel Structures ◽  
Driven System ◽  
Continuum Robot ◽  
Motion Characteristics ◽  
Novel Design

This paper presents a novel design for continuum robots in light of origami inspired folding techniques. The work of the present paper starts from design of a crease pattern, which consists of two triangular bases and three waterbomb bases, and folding process for creating an origami parallel structure in 3D from the crease pattern in 2D. Mapping the origami parallel structure to an equivalent kinematic model, the motion characteristics of the origami structure are unraveled in terms of kinematic principles. The analysis reveals that mixed rotational and translational motion of the origami parallel structure enables both axial contraction and bending motion. A novel multi-section continuum robot with integrated origami parallel structures and bias elements is then proposed to imitate not only bending motion but also contraction of continuum apparatus in nature. According to kinematics of the proposed continuum robot and features of the embedded helical spring in each module, three actuation schemes and their enabled two typical working phases with a tendon driven system are presented. A prototype of the continuum robot with six modules connected in serial is produced and tested. The functionality of the proposed continuum robot by integrating the origami parallel structure as its skeleton and helical springs as the compliant backbone is validated by the preliminary experimental results.

scholarly journals Task space-based orientability analysis and optimization of a wire-driven continuum robot

2019 ◽  
Vol 233 (23-24) ◽  
pp. 7658-7668
Author(s):  
Cong Wang ◽  
Shineng Geng ◽  
David T Branson ◽  
Chenghao Yang ◽  
Jian S Dai ◽  
...  
Keyword(s):  
Particle Swarm Optimization Algorithm ◽  
Kinematic Model ◽  
Task Space ◽  
Continuum Robots ◽  
Swarm Optimization ◽  
The Monte Carlo Method ◽  
Continuum Robot ◽  
Two Indices ◽  
Joint Length ◽  
The Continuum

Compared to traditional rigid robots, continuum robots have intrinsic compliance and therefore behave dexterously when performing tasks in restricted environments. Although there have been many researches on the design and application of continuum robots, a theoretical investigation of their dexterity is still lacking. In this paper, a two-joint wire-driven continuum robot is utilized to demonstrate dexterity by introducing the concept of orientability taking into account two indices, the accessible ratio and angle of the robot, when its tip reaches a certain task space inside the workspace. Based on the kinematic model, the accessible ratio and angle of the continuum robot are calculated using the Monte-Carlo method. From this, the influence of individual joint lengths on the proposed orientability indices and the optimal joint length are then investigated via an improved particle swarm optimization algorithm. Finally, the presented methods were validated through experiments showing that the use of optimal joint length can increase the accessible ratio and reduce the minimum accessible angle by more than 10° in the task space.

An Extensible Continuum Robot With Integrated Origami Parallel Modules

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
Ketao Zhang ◽  
Chen Qiu ◽  
Jian S. Dai
Keyword(s):  
Translational Motion ◽  
Kinematic Model ◽  
Parallel Structure ◽  
Continuum Robots ◽  
Helical Springs ◽  
Compression Spring ◽  
Driven System ◽  
Continuum Robot ◽  
Motion Characteristics ◽  
Novel Design

This paper presents a novel design of extensible continuum robots in light of origami-inspired folding techniques. The design starts from a modularized crease pattern, which consists of two triangular bases and three waterbomb bases, and generates a folding process for creating an origami waterbomb parallel structure. This further progresses to generating a compliant module with the origami parallel structure and a helical compression spring. A novel extensible continuum robot with the integrated compliant parallel modules is then proposed to imitate not only the bending motion but also the contraction of continuum creatures in nature. Mapping the origami parallel structure to an equivalent kinematic model, the motion characteristics of the origami structure are explored in terms of kinematic principles. The analysis reveals the mixed rotational and translational motion of the origami parallel module and the virtual axes for yaw and pitch motions. Following kinematics of the proposed continuum robot and features of the integrated helical spring in each module, three actuation schemes and resultant typical working phases with a tendon-driven system are presented. The design and analysis are then followed by a prototype of the extensible continuum robot with six integrated compliant modules connected in serial. The functionality of the proposed continuum robot with the origami parallel structure as its skeleton and the helical springs as the compliant backbone is validated by experimental results.

A New Extensible Continuum Manipulator Using Flexible Parallel Mechanism and Rigid Motion Transmission

2021 ◽  
pp. 1-23
Author(s):  
Yujiong Liu ◽  
Pinhas Ben-Tzvi
Keyword(s):  
Parallel Mechanism ◽  
Kinematic Model ◽  
Rigid Motion ◽  
Artificial Muscle ◽  
Dexterous Manipulation ◽  
Base Extension ◽  
Hybrid Mechanism ◽  
Continuum Robot ◽  
Kinematic Analyses ◽  
Continuum Manipulator

Abstract An extensible continuum manipulator (ECM) has specific advantages over its non-extensible counterparts. For instance, in certain applications, such as minimally invasive surgery or pipe inspection, the base motion might be limited or disallowed. The additional extensibility provides the robot with more dexterous manipulation and a larger workspace. Existing continuum robot designs achieve extensibility mainly through artificial muscle/pneumatic, extensible backbone, concentric tube, and base extension, etc. This paper proposes a new way to achieve this additional motion degree of freedom by taking advantage of the rigid coupling hybrid mechanism concept and a flexible parallel mechanism. More specifically, a rack and pinion set is used to transmit the motion of the i-th subsegment to drive the (i+1)-th subsegment. A six-chain flexible parallel mechanism is used to generate the desired spatial bending and one extension mobility for each subsegment. This way, the new manipulator can achieve tail-like spatial bending and worm-like extension at the same time. Simplified kinematic analyses are conducted to estimate the workspace and the motion non-uniformity. A proof-of-concept prototype was integrated to verify the mechanism’s mobility and to evaluate the kinematic model accuracy. The results show that the proposed mechanism achieved the desired mobilities with a maximum extension ratio of 32.2% and a maximum bending angle of 80 degrees.

An Analytical Tension Model for Continuum Robots with n Generally Positioned Tendons

2019 ◽  
Vol 04 (03n04) ◽  
pp. 1942003
Author(s):  
Mohsen Moradi Dalvand ◽  
Saeid Nahavandi ◽  
Robert D. Howe
Keyword(s):  
Stereo Vision ◽  
Control Algorithm ◽  
Open Loop ◽  
Open Loop Control ◽  
Continuum Robots ◽  
Loop Control ◽  
Proposed Model ◽  
Continuum Robot ◽  
Tension Loading ◽  
Tendon Compliance

The estimation of tension loads in multi-tendon continuum robots or catheters plays an important role not only in the design process but also in the control algorithm to avoid slack. An analytical tension loading model is developed that, for any given beam configuration within the workspace, calculates tendon tensions in [Formula: see text]-tendon continuum robots with general tendon positioning. The model accounts for the bending and axial compliance of the manipulator as well as tendon compliance. A 6-tendon continuum robot integrated with a stereo vision-based 3D reconstruction system is utilized to experimentally validate the proposed analytical model in open-loop control architecture. The proposed model demonstrates around 95% accuracy in estimating tendon tensions in a continuum robot with general tendon positioning and axial stretch in its tendons for all of the trials and experiments.

Development of a Multi-Cable-Driven Continuum Robot Controlled by Parallel Platforms

2020 ◽  
pp. 1-11 ◽  
Author(s):  
Xinbo Chen ◽  
Jiantao Yao ◽  
Tong Li ◽  
Haili Li ◽  
Pan Zhou ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Load Capacity ◽  
Continuum Robots ◽  
Position Accuracy ◽  
Continuum Robot ◽  
In Series ◽  
Kinematic Models ◽  
Parallel Platform ◽  
Tube Structure ◽  
The Continuum

Abstract Cable-driven continuum robots exhibit excellent capabilities in the unstructured environment due to their inherent compliance and dexterity. To improve the reliability and load capacity of continuum robots, increasing the number of cables is often used in the control of continuum robots. However, the number of actuators will increase with the cables. To tackle this challenge, this work proposes a method for increasing the number of cables without increasing actuators in a continuum robot through parallel platforms. The parallel platforms are used to control all the cables in the continuum robot, and can be separated from the continuum robot to enable the remote drive of a manipulation arm by using the cable-tube structure. The manipulation arm is composed of several independent bending modules in series, which can be configured freely according to the demand of degrees of freedom. Further, each bending module is controlled independently by a parallel platform, which can avoid the mutual interference between the cables of one bending module and another one, improve the position accuracy and simplify the control difficulty of the manipulation arm. To evaluate the proposed method, this work develops a prototype of six-cable-driven continuum robot controlled by 3RPS parallel platforms, and presents some basic kinematic models to describe its function, and then an experimental work characterizing its performance. Experimental results illustrated the importance of increasing the number of cables, the rationality of kinematic models of the continuum robot, and the feasibility of controlling multiple cables by a parallel platform.

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