Optimal, Model-Based Design of Soft Robotic Manipulators

2007 ◽  
Author(s):  
Deepak Trivedi ◽  
Dustin Dienno ◽  
Christopher D. Rahn
Keyword(s):  
Nonlinear Models ◽  
Load Capacity ◽  
Robotic Manipulators ◽  
Maximum Pressure ◽  
Cluttered Environments ◽  
Rod Theory ◽  
Cosserat Rod ◽  
Manipulator Design ◽  
Air Muscle ◽  
Muscle Actuators

Soft robotic manipulators, unlike their rigid-linked counterparts, deform continuously along their lengths similar to elephant trunks and octopus arms. Their excellent dexterity enables them to navigate through unstructured and cluttered environments and handle fragile objects using whole arm manipulation. Soft robotic manipulator design involves the specification of air muscle actuators and the number, length and configuration of sections that maximize dexterity and load capacity for a given maximum actuation pressure. This paper uses nonlinear models of the actuators and arm structure to optimally design soft robotic manipulators. The manipulator model is based on Cosserat rod theory, accounts for large curvatures, extensions, and shear strains, and is coupled to nonlinear Mooney-Rivlin actuator model. Given a dexterity constraint for each section, a genetic algorithm-based optimizer maximizes the arm load capacity by varying the actuator and section dimensions. The method generates design rules that simplify the optimization process. These rules are then applied to the design of pneumatically and hydraulically actuated soft robotic manipulators, using 100 psi and 1000 psi maximum pressure, respectively.

Optimal, Model-Based Design of Soft Robotic Manipulators

2008 ◽  
Vol 130 (9) ◽  
Author(s):  
Deepak Trivedi ◽  
Dustin Dienno ◽  
Christopher D. Rahn
Keyword(s):  
Nonlinear Models ◽  
Load Capacity ◽  
Robotic Manipulators ◽  
Cluttered Environments ◽  
Rod Theory ◽  
Cosserat Rod ◽  
Manipulator Design ◽  
Air Muscle ◽  
Muscle Actuators ◽  
General Method

Soft robotic manipulators, unlike their rigid-linked counterparts, deform continuously along their lengths similar to elephant trunks and octopus arms. Their excellent dexterity enables them to navigate through unstructured and cluttered environments and to handle fragile objects using whole arm manipulation. This paper develops optimal designs for OctArm manipulators, i.e., multisection, trunklike soft arms. OctArm manipulator design involves the specification of air muscle actuators and the number, length, and configuration of sections that maximize dexterity and load capacity for a given maximum actuation pressure. A general method of optimal design for OctArm manipulators using nonlinear models of the actuators and arm mechanics is developed. The manipulator model is based on Cosserat rod theory, accounts for large curvatures, extensions, and shear strains, and is coupled to the nonlinear Mooney–Rivlin actuator model. Given a dexterity constraint for each section, a genetic algorithm-based optimizer maximizes the arm load capacity by varying the actuator and section dimensions. The method generates design rules that simplify the optimization process. These rules are then applied to the design of pneumatically and hydraulically actuated OctArm manipulators using 100psi and 1000psi maximum pressures, respectively.

Optimization in the Design and Control of Robotic Manipulators: A Survey

1989 ◽  
Vol 42 (4) ◽  
pp. 117-128 ◽  
Author(s):  
S. S. Rao ◽  
P. K. Bhatti
Keyword(s):  
Optimal Control ◽  
Robot Manipulator ◽  
Research Effort ◽  
Industrial Robot ◽  
Load Capacity ◽  
Robotic Manipulators ◽  
Optimization Techniques ◽  
Highly Nonlinear ◽  
Manipulator Design ◽  
And Control

Robotics is a relatively new and evolving technology being applied to manufacturing automation and is fast replacing the special-purpose machines or hard automation as it is often called. Demands for higher productivity, better and uniform quality products, and better working environments are primary reasons for its development. An industrial robot is a multifunctional and computer-controlled mechanical manipulator exhibiting a complex and highly nonlinear behavior. Even though most current robots have anthropomorphic configurations, they have far inferior manipulating abilities compared to humans. A great deal of research effort is presently being directed toward improving their overall performance by using optimal mechanical structures and control strategies. The optimal design of robot manipulators can include kinematic performance characteristics such as workspace, accuracy, repeatability, and redundancy. The static load capacity as well as dynamic criteria such as generalized inertia ellipsoid, dynamic manipulability, and vibratory response have also been considered in the design stages. The optimal control problems typically involve trajectory planning, time-optimal control, energy-optimal control, and mixed-optimal control. The constraints in a robot manipulator design problem usually involve link stresses, actuator torques, elastic deformation of links, and collision avoidance. This paper presents a review of the literature on the issues of optimum design and control of robotic manipulators and also the various optimization techniques currently available for application to robotics.

scholarly journals A discrete mechanics approach to the Cosserat rod theory-Part 1: static equilibria

2010 ◽  
Vol 85 (1) ◽  
pp. 31-60 ◽  
Author(s):  
Pascal Jung ◽  
Sigrid Leyendecker ◽  
Joachim Linn ◽  
Michael Ortiz
Keyword(s):  
Discrete Mechanics ◽  
Rod Theory ◽  
Cosserat Rod

An Approximate THD Theory for Journal Bearings

1990 ◽  
Vol 112 (2) ◽  
pp. 224-229 ◽  
Author(s):  
G. Gupta ◽  
C. R. Hammond ◽  
A. Z. Szeri
Keyword(s):  
Journal Bearing ◽  
Load Capacity ◽  
Pressure Coefficient ◽  
Journal Bearings ◽  
Maximum Pressure ◽  
Substantial Agreement ◽  
Interactive Mode ◽  
Lubricant Flow ◽  
Bearing Load ◽  
Sophisticated Model

The aim of this paper is to make available to the industrial designer results of the thermohydrodynamic theory of journal bearings, by providing a simplified, yet accurate model of journal bearing lubrication that can be implemented on a personal computer and be used in an interactive mode. The simplified THD theory we propose consists of two coupled ordinary differential equations for pressure and energy and an algebraic equation for viscosity, which are to be solved iteratively. Bearing load capacity, maximum bearing temperature, maximum pressure, coefficient of friction and lubricant flow rate calculated from this simplified theory compare well with results from a more sophisticated model. We also make comparisons with experimental data on full journal bearings, demonstrating substantial agreement between experiment and simplified theory.

scholarly journals Integration of Nonlinear Models of Flexible Body Deformation in Multibody System Dynamics

2013 ◽  
Vol 9 (1) ◽  
Author(s):  
Martin Schulze ◽  
Stefan Dietz ◽  
Bernhard Burgermeister ◽  
Andrey Tuganov ◽  
Holger Lang ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Multibody System ◽  
Nonlinear Models ◽  
Equations Of Motion ◽  
Flexible Structures ◽  
General Purpose ◽  
Cosserat Rod ◽  
Rod Model ◽  
Flexible Deformation ◽  
Run Up

Current challenges in industrial multibody system simulation are often beyond the classical range of application of existing industrial simulation tools. The present paper describes an extension of a recursive order-n multibody system (MBS) formulation to nonlinear models of flexible deformation that are of particular interest in the dynamical simulation of wind turbines. The floating frame of reference representation of flexible bodies is generalized to nonlinear structural models by a straightforward transformation of the equations of motion (EoM). The approach is discussed in detail for the integration of a recently developed discrete Cosserat rod model representing beamlike flexible structures into a general purpose MBS software package. For an efficient static and dynamic simulation, the solvers of the MBS software are adapted to the resulting class of MBS models that are characterized by a large number of degrees of freedom, stiffness, and high frequency components. As a practical example, the run-up of a simplified three-bladed wind turbine is studied where the dynamic deformations of the three blades are calculated by the Cosserat rod model.

Static thermal performance evaluation of elliptical journal bearings with nanolubricants

2020 ◽  
pp. 135065012097074
Author(s):  
Rajeev Kumar Dang ◽  
Amit Chauhan ◽  
SS Dhami
Keyword(s):  
Thermal Performance ◽  
Load Capacity ◽  
Journal Bearings ◽  
Maximum Pressure ◽  
Stable Operation ◽  
Base Oil ◽  
Lubrication Film ◽  
Mineral Oils ◽  
Appreciable Increase ◽  
Thermo Physical Properties

Journal bearings of different configurations have been extensively used in turbomachinery and power generating equipments. Although circular bearings have simplest configuration and commonly used journal bearings, non-circular bearings such as multi-lobe and elliptical bearings have an added advantage of lower lubrication film temperature alongwith stable operation. In this study, static thermal performance of pure elliptical bearing lubricated with nanoparticles based mineral oils has been studied at different eccentricity ratios and bearing speeds. Two types of nanoparticles, namely, CuO and TiO2 with 0.5, 1.0 and 2.0 wt.% concentrations have been separately added in three different viscosity grades of oils. The effect of nanoparticles on thermo-physical properties of oil was considered to compute bearing performance parameters (pressure distribution, load capacity, oil temperature and power losses). Bearing model was generated by taking into account the modified Krieger Dougherty method to determine viscosity at different combinations of oils and nanoparticles. The findings indicate the increase in maximum pressure and load capacity with addition of nanoparticles and this increase was more pronounced at higher concentrations of nanoparticles and at higher viscosity grade oils. Load capacity was found to be increased by 14.24% and 9.21% with 2 wt% concentration of TiO2 and CuO nanoparticles respectively in base oil (AW68) at eccentricity ratio of 0.7. An increase in load capacity with nanolubricants was achieved without an appreciable increase in oil temperature.

Design of a Soft Multi-Degree of Freedom Tool Positioner With Variable Stiffness Integrating Molded Air Muscles Actuation, Granular Jamming and Dielectric Elastomer Sensing

2015 ◽  
Author(s):  
Guillaume Bouliane-Blais ◽  
Jean-Sébastien Plante
Keyword(s):  
Variable Stiffness ◽  
Dielectric Elastomer ◽  
Degree Of Freedom ◽  
Soft Robotics ◽  
Initial Stiffness ◽  
Trade Off ◽  
Position Feedback ◽  
Constrained Environments ◽  
Air Muscle ◽  
Muscle Actuators

Soft technology is more and more present in robotics allowing safe interaction with humans, high dexterity in constrained environments, and safe manipulation of fragile or undefined objects. However, soft robotics is limited by a fundamental trade-off between available workspace and stiffness. Position feedback is also challenging as soft robots generally use deformable mechanisms instead of discrete joints. Here, the design of a soft four-degree-of-freedom tool positioner integrating a brake system and a soft sensor is proposed to address these issues. The design integrates molded air muscle actuators, granular jamming brakes, and Dielectric Elastomer Sensors (DES). The design is experimentally validated based on the requirements of a manipulator for liver cancer treatment, which is a representative application of soft robotics. The use of granular jamming mitigates the fundamental trade-off of soft robotics as it allows the manipulator to reach a large workspace (1500 cm3) while having the capacity to provide a high stiffness (up to19 times the initial stiffness). DES provides satisfactory position feedback, demonstrating a 0.69 mm accuracy that is lower than the 1 mm requirement. The proposed design using granular jamming and DES could greatly benefit human-safe and medical robotics.

Condensing Vapor Lubrication of Self-Acting Long Journal Bearings

1966 ◽  
Vol 88 (1) ◽  
pp. 236-245 ◽  
Author(s):  
W. Unterberg ◽  
J. S. Ausman
Keyword(s):  
Load Capacity ◽  
Saturation Pressure ◽  
Journal Bearings ◽  
Variable Pressure ◽  
Maximum Pressure ◽  
Two Phase ◽  
Bearing Load ◽  
Phase Liquid ◽  
High Pressure Region ◽  
Vapor Region

This is a theoretical investigation into the behavior of self-acting long journal bearings lubricated with vapor which may partially condense in the high-pressure region of a loaded bearing. Thermohydrodynamic considerations indicate that the lubricant temperature remains constant throughout the bearing. When the maximum pressure in the bearing reaches the saturation vapor pressure at the constant temperature, a further increase in bearing load then causes partial condensation instead of a rise in maximum pressure. In the partial condensation regime, the fluid annulus is made up of (a) a single-phase vapor region with variable pressure, and (b) a two-phase liquid-vapor region at constant saturation pressure. The regional interface locations and the bearing pressure distribution are obtained by “linearized ph” methods under the restrictions or boundary conditions of saturation pressure at the interfaces and constant lubricant mass content. It is shown that complete condensation cannot occur, so that the maximum pressure in the condensing vapor-lubricated bearing is limited to the saturation pressure. For this reason, the resulting load capacity always lies below that of a corresponding bearing lubricated with a noncondensing gas.

Magnetically-doped polydimethylsiloxane for artificial muscle applications

2019 ◽  
Vol 13 (01) ◽  
pp. 1950089
Author(s):  
Erik Ventura ◽  
Cagri Oztan ◽  
Diego Palacios ◽  
Irene Isabel Vargas ◽  
Emrah Celik
Keyword(s):  
Additive Manufacturing ◽  
Mechanical Response ◽  
Load Capacity ◽  
Artificial Muscle ◽  
Artificial Muscles ◽  
Test Results ◽  
Method Of Production ◽  
Muscle Actuators ◽  
Doped Polymer

Artificial muscle actuators demonstrate great potential for improving the quality of life. Recently, polymer muscle actuators have attracted attention due to their inexpensive and highly versatile methods of fabrication along with decent mechanical properties that can mimic those of natural muscles. The aim of this research is to investigate the usability of a magnetite-doped polymer powder, polydimethylsiloxane (PDMS), for artificial muscle actuators through an inexpensive method of production. PDMS samples doped with different levels of magnetite were fabricated using molds that were produced by additive manufacturing. Subsequently, the samples were magnetically and mechanically characterized by investigation of strength, elastic modulus, failure strain and permittivity, which are vital to meet the load capacity. The test results demonstrated that the mechanical and magnetic properties could be tailored as a function of doping level. Matching the mechanical response of these artificial components to those of artificial muscles will reduce the residual stresses, enhance the artificial muscle life and allow wider use of these materials for biomedical applications. This research rendered fabrication of molds possible for various applications where geometric customization of the actuator is required to meet endure severe loads, thanks to the freeform nature of additive manufacturing.

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