Model-Based Shape Estimation for Soft Robotic Manipulators: The Planar Case

2014 ◽  
Vol 6 (2) ◽  
Author(s):  
Deepak Trivedi ◽  
Christopher D. Rahn
Keyword(s):  
Degrees Of Freedom ◽  
Soft Materials ◽  
Robotic Manipulators ◽  
Shape Estimation ◽  
Sensors And Actuators ◽  
Backbone Curve ◽  
Planar Case ◽  
Soft Robots ◽  
Estimation And Control ◽  
Shape Sensing

Soft robotic manipulators are continuum robots made of soft materials that undergo continuous elastic deformation and produce motion with a smooth backbone curve. In many applications, these manipulators offer significant advantages over traditional manipulators due to their ability to conform to their surroundings, and manipulate objects of widely varying size using whole arm manipulation. Theoretically, soft robots have infinite degrees of freedom (DOF), but the number of sensors and actuators are limited. Many DOFs of soft robots are not directly observable and/or controllable, complicating shape estimation and control. In this paper, we present three methods of shape sensing for soft robotic manipulators based on a geometrically exact mechanical model. The first method uses load cells mounted at the base of the manipulator, the second method makes use of cable encoders running through the length of the manipulator, and the third method uses inclinometers mounted at the end of each section of the manipulator. Simulation results show an endpoint localization error of less than 3% of manipulator length with typical sensors. The methods are validated experimentally on the OctArm VI manipulator.

Shape Sensing for Soft Robotic Manipulators

2009 ◽  
Author(s):  
Deepak Trivedi ◽  
Christopher D. Rahn
Keyword(s):  
Degrees Of Freedom ◽  
Soft Materials ◽  
Robotic Manipulators ◽  
Sensors And Actuators ◽  
Backbone Curve ◽  
Continuum Robots ◽  
Soft Robots ◽  
Load Cells ◽  
Simulation Results ◽  
Shape Sensing

Soft robotic manipulators are continuum robots made of soft materials that undergo continuous elastic deformation and produce motion with a smooth backbone curve. These manipulators offer significant advantages over traditional manipulators due to their ability to conform to their surroundings, move with dexterity and manipulate objects of widely varying size using whole arm manipulation. Theoretically, soft robots have infinite degrees of freedom (dof), but the number of sensors and actuators are limited. Many dofs of soft robots are not directly observable and/or controllable, complicating shape sensing and controlling. In this paper, we present two methods of shape sensing for soft robotic manipulators based on a geometrically exact mechanical model. The first method use s load cells mounted at the base of the manipulator and the second method makes use of cable encoders running through the length of the manipulator. Simulation results show an endpoint localization error of less than 3% of manipulator length.

scholarly journals Stretchable optical fibre sensor for soft surgical robot shape reconstruction

2021 ◽  
Vol 51 (4) ◽  
Author(s):  
Yanlin He ◽  
Likun Gao ◽  
Yuchen Bai ◽  
Hangwei Zhu ◽  
Guangkai Sun ◽  
...  
Keyword(s):  
Optical Fibre ◽  
Soft Materials ◽  
Maximum Error ◽  
Shape Reconstruction ◽  
Fibre Bragg Grating ◽  
Soft Robot ◽  
Soft Robots ◽  
Optical Fibre Sensor ◽  
Fibre Sensor ◽  
Shape Sensing

Soft robotics presents several advantages in the field of minimally invasive surgery. However, existing methods have not fully addressed problems related to soft robot shape sensing due to the complex motion of soft robots and the stretchable nature of the soft materials employed. This study demonstrates the shape sensing of a soft robot with a helically embedded stretchable fibre Bragg grating (FBG)-based optical fibre sensor. Unlike straight FBG embedding configurations, this unique helical configuration prevents sensor dislocation, supports material stretchability, and facilitates shape detection for various soft-robot movements. The proposed soft-robot design principle and FBG sensor are analysed and their fabrication process, which includes an FBG-written optical fibre sensor, is described. Bending experiments are conducted with the soft robot, the wavelengths of FBG sensors at different bending and telescopic movement states are obtained, and the soft-robot shape is reconstructed. Experimental results demonstrate that the maximum error between FBG sensing and the actual bending state is less than 2.5%, validating the feasibility and effectiveness of the proposed helical stretchable FBG sensing method for the shape measurement of soft robots. These results indicate the potential and applicability of this shape-sensing approach in biomedical research.

Dexterity and Workspace Analysis of Two Soft Robotic Manipulators

2010 ◽  
Author(s):  
Deepak Trivedi ◽  
Daniel Lesutis ◽  
Christopher D. Rahn
Keyword(s):  
Elastic Deformation ◽  
Cost Effective ◽  
Soft Materials ◽  
Robotic Manipulators ◽  
Backbone Curve ◽  
Continuum Robots ◽  
Workspace Analysis ◽  
Air Muscle ◽  
Distal Section ◽  
Effective Design

Soft robotic manipulators are continuum robots made of soft materials that undergo continuous elastic deformation and produce motion with a smooth backbone curve. These manipulators offer significant advantages over traditional manipulators due to their ability to conform to their surroundings, move with dexterity and manipulate objects of widely varying size using whole arm manipulation. Soft robotic manipulators are complex and difficult to design, model and fabricate. In this paper, we present a cost effective design for a pneumatic air muscle based soft robotic manipulator in which the actuators for the distal section extend from the base to the tip of the arm, thereby simplifying the pneumatic design and eliminating the need for endplates. We compare the workspace and dexterity of continuous tube (CT) design with a previously developed OctArm type manipulator and conclude that although the two designs have comparable workspace area, the OctArm workspace has better dexterity characteristics.

scholarly journals Task space adaptation via the learning of gait controllers of magnetic soft millirobots

2021 ◽  
pp. 027836492110218
Author(s):  
Sinan O. Demir ◽  
Utku Culha ◽  
Alp C. Karacakol ◽  
Abdon Pena-Francesch ◽  
Sebastian Trimpe ◽  
...  
Keyword(s):  
Human Body ◽  
Degrees Of Freedom ◽  
Bayesian Optimization ◽  
Small Scale ◽  
Soft Robots ◽  
Modeling And Control ◽  
Walking Gait ◽  
Physical Experiments ◽  
Efficient Learning ◽  
Task Environments

Untethered small-scale soft robots have promising applications in minimally invasive surgery, targeted drug delivery, and bioengineering applications as they can directly and non-invasively access confined and hard-to-reach spaces in the human body. For such potential biomedical applications, the adaptivity of the robot control is essential to ensure the continuity of the operations, as task environment conditions show dynamic variations that can alter the robot’s motion and task performance. The applicability of the conventional modeling and control methods is further limited for soft robots at the small-scale owing to their kinematics with virtually infinite degrees of freedom, inherent stochastic variability during fabrication, and changing dynamics during real-world interactions. To address the controller adaptation challenge to dynamically changing task environments, we propose using a probabilistic learning approach for a millimeter-scale magnetic walking soft robot using Bayesian optimization (BO) and Gaussian processes (GPs). Our approach provides a data-efficient learning scheme by finding the gait controller parameters while optimizing the stride length of the walking soft millirobot using a small number of physical experiments. To demonstrate the controller adaptation, we test the walking gait of the robot in task environments with different surface adhesion and roughness, and medium viscosity, which aims to represent the possible conditions for future robotic tasks inside the human body. We further utilize the transfer of the learned GP parameters among different task spaces and robots and compare their efficacy on the improvement of data-efficient controller learning.

Behavior of a smart one-way micro-valve considering fluid–structure interaction

2018 ◽  
Vol 29 (20) ◽  
pp. 3960-3971 ◽  
Author(s):  
H Mazaheri ◽  
AH Namdar ◽  
A Amiri
Keyword(s):  
Interaction Effect ◽  
Fluid Structure Interaction ◽  
Pressure Head ◽  
Soft Materials ◽  
Crosslinking Density ◽  
Operational Parameters ◽  
Sensors And Actuators ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Different Temperatures

Smart hydrogels are soft materials which can be applied in sensors and actuators especially in microfluidics in which the fluid–structure interaction is important. In this work, first, the behavior of a one-way hydrogel micro-valve is investigated by considering the fluid–structure interaction effect for a specified geometry of the micro-valve. Second, both the fluid–structure interaction and non-fluid–structure interaction simulations are conducted to study the fluid flow effect on the operational parameters of the micro-valve. The obtained results show that the fluid–structure interaction effects are important and have a considerable influence on the micro-valve parameters especially on its closing temperature. Thereafter, a precise study on the micro-valve is executed by considering the micro-valve operational parameters such as inlet pressure, head size, crosslinking density, and breaking pressure at different temperatures. The results show the importance of considering the fluid–structure interaction effect in the design of these devices.

scholarly journals Planning Fail-Safe Trajectories for Space Robotic Arms

2021 ◽  
Vol 8 ◽  
Author(s):  
Oliver Porges ◽  
Daniel Leidner ◽  
Máximo A. Roa
Keyword(s):  
Degrees Of Freedom ◽  
Fault Tolerant ◽  
Robotic Manipulators ◽  
Task Completion ◽  
Joint Failure ◽  
Space Applications ◽  
Robotic Arms ◽  
Hazardous Environments ◽  
Potential Risks ◽  
Fail Safe

A frequent concern for robot manipulators deployed in dangerous and hazardous environments for humans is the reliability of task executions in the event of a joint failure. A redundant robotic manipulator can be used to mitigate the risk and guarantee a post-failure task completion, which is critical for instance for space applications. This paper describes methods to analyze potential risks due to a joint failure, and introduces tools for fault-tolerant task design and path planning for robotic manipulators. The presented methods are based on off-line precomputed workspace models. The methods are general enough to cope with robots with any type of joint (revolute or prismatic) and any number of degrees of freedom, and might include arbitrarily shaped obstacles in the process, without resorting to simplified models. Application examples illustrate the potential of the approach.

Piezothermoelasticity and Control of Piezoelectric Laminates Exposed to a Steady-State Temperature Field

1993 ◽  
Author(s):  
H. S. Tzou ◽  
R. Ye
Keyword(s):  
Temperature Field ◽  
Steady State ◽  
Degrees Of Freedom ◽  
Sensors And Actuators ◽  
System Equation ◽  
Thermal Fields ◽  
Steady State Temperature ◽  
And Control ◽  
Internal Degrees Of Freedom

Abstract Piezothermoelastic effects of distributed piezoelectric sensors and actuators are investigated. Vibration control of piezoelectric laminates subjected to a steady-state temperature field is studied. A new 3-D piezothermoelastic finite element with three internal degrees of freedom is formulated using a variational formulation. A system equation for the piezoelectric continuum exposed to combined elastic, electric, and thermal fields is formulated. Distributed sensing and control equations are derived. All these effects are studied in a case study.

A Robotic Cell for Embedding Prefabricated Components in Extrusion-Based Additive Manufacturing

2020 ◽  
Author(s):  
Yeo Jung Yoon ◽  
Oswin G. Almeida ◽  
Aniruddha V. Shembekar ◽  
Satyandra K. Gupta
Keyword(s):  
Additive Manufacturing ◽  
Degrees Of Freedom ◽  
Robotic Manipulators ◽  
The Other ◽  
Robotic Arm ◽  
Robotic Cell ◽  
Material Extrusion ◽  
Surface Polishing ◽  
Pick And Place ◽  
6 Degrees Of Freedom

Abstract By attaching a material extrusion system to a robotic arm, we can deposit materials onto complex surfaces. Robotic manipulators can also maximize the task utility by performing other tasks such as assembly or surface polishing when they are not in use for the AM process. We present a robotic cell for embedding prefabricated components in extrusion-based AM. The robotic cell consists of two 6 degrees of freedom (DOF) robots, an extrusion system, and a gripper. One robot is used for printing a part, and the other robot takes a support role to pick and place the prefabricated component and embed it into the part being printed. After the component is embedded, AM process resumes, and the material is deposited onto the prefabricated components and previously printed layers. We illustrate the capabilities of the system by fabricating three objects.

Analysis of Varying Natural Frequencies and Damping Ratios of a Sample Parallel Manipulator Throughout its Workspace Using Linearized Equations of Motion

2001 ◽  
Author(s):  
Kris Kozak ◽  
Imme Ebert-Uphoff ◽  
William Singhose
Keyword(s):  
Degrees Of Freedom ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Equations Of Motion ◽  
Parallel Architecture ◽  
Robotic Manipulators ◽  
Parallel Manipulators ◽  
Dynamic Equations ◽  
Extreme Variation

Abstract This article investigates the dynamic properties of robotic manipulators of parallel architecture. In particular, the dependency of the dynamic equations on the manipulator’s configuration within the workspace is analyzed. The proposed approach is to linearize the dynamic equations locally throughout the workspace and to plot the corresponding natural frequencies and damping ratios. While the results are only applicable for small velocities of the manipulator, they present a first step towards the classification of the nonlinear dynamics of parallel manipulators. The method is applied to a sample manipulator with two degrees-of-freedom. The corresponding numerical results demonstrate the extreme variation of its natural frequencies and damping ratios throughout the workspace.

Identification of Structural Systems With Limited Number of Sensors and Actuators

2004 ◽  
Author(s):  
Jun Yu ◽  
Maura Imbimbo ◽  
Raimondo Betti
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Models ◽  
Solution Space ◽  
Order Model ◽  
Sensors And Actuators ◽  
Common Assumption ◽  
Reduced Order ◽  
Different Types ◽  
The Common ◽  
Inverse Vibration

The common assumption in the so-called linear inverse vibration problem, which provides the mass/stiffness/damping matrices of second order dynamic models, is the availability of a full set of sensors and actuators. In “reduced-order” problems (with limited number of instrumentation), only the components of the eigenvector matrix regarding the measured degrees of freedom can be successfully identified while nothing can be said about the components connected to the unmeasured degrees of freedom. This paper presents a recently developed “reduced-order” model and expands such a model to a “full-order” one that is quite useful in damage detection. The five representative categories of “reduced-order” problems, defined by considering different types of geometrical conditions, are analyzed and a discussion on their solution space has been performed. The effectiveness and robustness of this approach is shown by means of a numerical example.

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