Kinematic Control and Obstacle Avoidance for Soft Inflatable Manipulator

Ataka, Ahmad; Stilli, Agostino; Konstantinova, Jelizaveta; Würdemann, Helge A.; Althoefer, Kaspar

doi:10.1007/978-3-030-23807-0_5

Cited by 5 publications

(3 citation statements)

References 21 publications

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“…Recent work explores position and stiffness control of a soft robot with antagonistic pneumatic-tendon actuators [22]. Kinematic control for an inflatable manipulator which considers the change in structural stiffness has also been reported recently [23]. However, none of these works considers a simultaneous position and orientation control of the tip which is crucial in many applications such as object grasping and pick-and-place tasks.…”

Section: Introductionmentioning

confidence: 99%

Model-Based Pose Control of Inflatable Eversion Robot With Variable Stiffness

Ataka

Abrar

Putzu

et al. 2020

IEEE Robot. Autom. Lett.

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Plant-inspired inflatable eversion robots with their tip growing behaviour have recently emerged. Because they extend from the tip, eversion robots are particularly suitable for applications that require reaching into remote places through narrow openings. Besides, they can vary their structural stiffness. Despite these essential properties which make the eversion robot a promising candidate for applications involving cluttered environments and tight spaces, controlling their motion especially laterally has not been investigated in depth. In this paper, we present a new approach based on model-based kinematics to control the eversion robot's tip position and orientation. Our control approach is based on Euler-Bernoulli beam theory which takes into account the effect of the internal inflation pressure to model each robot bending segment for various conditions of structural stiffness. We determined the parameters of our bending model by performing a least-square technique based on the pressure-bending data acquired from an experimental study. The model is then used to develop a pose controller for the tip of our eversion robot. Experimental results show that the proposed control strategy is capable of guiding the tip of the eversion robot to reach a desired position and orientation whilst varying its structural stiffness.

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Section: Introductionmentioning

confidence: 99%

Model-Based Pose Control of Inflatable Eversion Robot With Variable Stiffness

Ataka

Abrar

Putzu

et al. 2020

IEEE Robot. Autom. Lett.

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“…Other extended approach for soft robots control are based on kinematic models. The challenge of kinematic control of soft robots lies in complex models depending on a large number of parameters (e.g., actuation mechanism, materials, redundancy) [29], [30], [36], [32]. Three main approaches exist: model-based, model-free and hybrid kinematics [33].…”

Section: Introductionmentioning

confidence: 99%

Open-Loop Position Control in Collaborative, Modular Variable-Stiffness-Link (VSL) Robots

Gandarias

Wang

Stilli

et al. 2020

IEEE Robot. Autom. Lett.

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Collaborative robots (cobots) open up new avenues in the fields of industrial robotics and physical Human-Robot Interaction (pHRI) as they are suitable to work in close approximation and in collaboration with humans. The integration and control of variable stiffness elements allow inherently safe interaction. Apart from notable work on Variable Stiffness Actuators, the concept of Variable-Stiffness-Link (VSL) manipulators promises safety improvements in cases of unintentional physical collisions. However, position control of these type of robotic manipulators is challenging for critical task-oriented motions (e.g., pick and place). Hence, the study of open-loop position control for VSL robots is crucial to achieve high levels of safety, accuracy and hardware cost-efficiency in pHRI applications. In this paper, we propose a hybrid, learning based kinematic modelling approach to improve the performance of traditional open-loop position controllers for a modular, collaborative VSL robot. We show that our approach improves the performance of traditional open-loop position controllers for robots with VSL and compensates for position errors, in particular, for lower stiffness values inside the links: Using our upgraded and modular robot, two experiments have been carried out to evaluate the behaviour of the robot during taskoriented motions. Results show that traditional model-based kinematics are not able to accurately control the position of the end-effector: the position error increases with higher loads and lower pressures inside the VSLs. On the other hand, we demonstrate that, using our approach, the VSL robot can outperform the position control compared to a robotic manipulator with 3D printed rigid links.

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“…These soft actuators overcome the barriers of their rigid counterparts in aspects such as safety, adaptability, and low cost. They have made a mark in many application areas including grasping of delicate and fragile objects [1], wearable robots [2,3], and exploration of extreme environments that are not accessible by humans [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

An Inhomogeneous Structured Eversion Actuator

Abrar

Hassan

Putzu

et al. 2020

Towards Autonomous Robotic Systems

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Soft actuators are free from any rigid, bulky, and hard components. This is greatly beneficial towards achieving compliant actuation and safe interactions in robots. Inspired by the eversion principle, we develop a novel soft actuator of the inhomogeneous cross-section that can linearly extend and achieve a large payload capability. The proposed soft actuator is a hollow sleeve, made from an airtight fabric, and features a top part of cylindrical shape and a bottom part of a conical shape. Unlike conventional eversion robots that extend unilaterally from the tip, in this proposed actuator the top cylindrical part and the bottom conical part are partially folded inwards so that the two tips are attached together. When pneumatic pressure is applied, the cylindrical part everts increasing in length while the conical section reduces in length folding inwards. The actuator achieves linear strains of 120% and can generate a force of 84N at a low pressure of 62kPa. We develop a theoretical model to describe the force and strain characteristics of the actuator during eversion from conical shape to cylindrical shape. The results showcase a step towards large strain, high force actuators for safe and compliant robots.

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Kinematic Control and Obstacle Avoidance for Soft Inflatable Manipulator

Cited by 5 publications

References 21 publications

Model-Based Pose Control of Inflatable Eversion Robot With Variable Stiffness

Model-Based Pose Control of Inflatable Eversion Robot With Variable Stiffness

Open-Loop Position Control in Collaborative, Modular Variable-Stiffness-Link (VSL) Robots

An Inhomogeneous Structured Eversion Actuator

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