Gripping by controllable wet adhesion using a magnetorheological fluid

The magnetorheological properties of ferrofluids (or smart, or active fluids) are well known, and are currently exploited in shear in advanced damping systems in the automotive industry, robotics (prosthesis), and machine tools (chatter reduction, positioning). This paper proposes an end effector for gripping by a novel form of controllable wet adhesion inspired by gastropod pedal mucus. The design of a gripper has been proposed, along with performance analysis based on experiments on various parameters, materials and surfaces, exhibiting robustness in unknown and dirty environment, typical of disassembly. Benefits over competing handling technologies and future research directions in this new area have been addressed

Rough-terrain mobile robot planning and control with application to planetary exploration

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.Includes bibliographical references (leaves 119-130).Future planetary exploration missions will require mobile robots to perform difficult tasks in highly challenging terrain, with limited human supervision. Current motion planning and control algorithms are not well suited to rough-terrain mobility, since they generally do not consider the physical characteristics of the rover and its environment. Failure to understand these characteristics could lead to rover entrapment and mission failure. In this thesis, methods are presented for improved rough-terrain mobile robot mobility, which exploit fundamental physical models of the rover and terrain. Wheel-terrain interaction has been shown to be critical to rough terrain mobility. A wheel-terrain interaction model is presented, and a method for on-line estimation of important model parameters is proposed. The local terrain profile also strongly influences robot mobility. A method for on-line estimation of wheel-terrain contact angles is presented. Simulation and experimental results show that wheel-terrain model parameters and contact angles can be estimated on-line with good accuracy. Two rough-terrain planning algorithms are introduced. First, a motion planning algorithm is presented that is computationally efficient and considers uncertainty in rover sensing and localization. Next, an algorithm for geometrically reconfiguring the rover kinematic structure to optimize tipover stability margin is presented. Both methods utilize models developed earlier in the thesis.(cont.) Simulation and experimental results on the Jet Propulsion Laboratory Sample Return Rover show that the algorithms allow highly stable, semi-autonomous mobility in rough terrain. Finally, a rough-terrain control algorithm is presented that exploits the actuator redundancy found in multi-wheeled mobile robots to improve ground traction and reduce power consumption. The algorithm uses models developed earlier in the thesis. Simulation and experimental results show that the algorithm leads to improved wheel thrust and thus increased mobility in rough terrain.by Karl David Iagnemma.Ph.D

A controllably adhesive climbing robot using magnetorheological fluid

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 67-69).In this thesis, the novel adhesive effects of magnetorheological fluid for use in climbing robotics were experimentally measured and compared to existing cohesive failure fluid models of yield stress adhesion. These models were found to correlate with experimental results at yield stresses below 1.12 kPa. MR fluid samples activated to have yield stresses above 1.12 kPa were limited to an adhesive stress of approximately 25-30 kPa regardless of inital fluid thickness or yield stress. A climbing robot capable of utilizing MR fluid adhesion was constructed and shown to be capable of adhering to surfaces of any orientation and climbing rough surfaces with a 45° slope. The robot was capable of controllably adhering to rough sandpaper and smooth glass with an adhesive stress of 7.3 kPa, demonstrating a novel form of adhesion on a wide range of surface roughnesses and orientations.by Nicholas Eric Wiltsie.S.M

A Stiffness-Adjustable Hyperredundant Manipulator Using a Variable Neutral-Line Mechanism for Minimally Invasive Surgery

In robotic single-port surgery, it is desirable for a manipulator to exhibit the property of variable stiffness. Small-port incisions may require both high flexibility of the manipulator for safety purposes, as well as high structural stiffness for operational precision and high payload capability. This paper presents a new hyperredundant tubular manipulator with a variable neutral-line mechanisms and adjustable stiffness. A unique asymmetric arrangement of the tendons and the links realizes both articulation of the manipulator and continuous stiffness modulation. This asymmetric motion of the manipulator is compensated by a novel actuation mechanism without affecting its structural stiffness. The paper describes the basic mechanics of the variable neutral-line manipulator, and its stiffness characteristics. Simulation and experimental results verify the performance of the proposed mechanism.Samsung Advanced Institute of Technolog

Modeling of the interaction of rigid wheels with dry granular media

We analyze the capabilities of various recently developed techniques, namely Resistive Force Theory (RFT) and continuum plasticity implemented with the Material Point Method (MPM), in capturing dynamics of wheel--dry granular media interactions. We compare results to more conventionally accepted methods of modeling wheel locomotion. While RFT is an empirical force model for arbitrarily-shaped bodies moving through granular media, MPM-based continuum modeling allows the simulation of full granular flow and stress fields. RFT allows for rapid evaluation of interaction forces on arbitrary shaped intruders based on a local surface stress formulation depending on depth, orientation, and movement of surface elements. We perform forced-slip experiments for three different wheel types and three different granular materials, and results are compared with RFT, continuum modeling, and a traditional terramechanics semi-empirical method. Results show that for the range of inputs considered, RFT can be reliably used to predict rigid wheel granular media interactions with accuracy exceeding that of traditional terramechanics methodology in several circumstances. Results also indicate that plasticity-based continuum modeling provides an accurate tool for wheel-soil interaction while providing more information to study the physical processes giving rise to resistive stresses in granular media

XTerramechanics: Integrated Simulation of Planetary Surface Missions

Are there contemporary habitats elsewhere in the solar system with necessary conditions, organic matter, water, energy, and nutrients to support or sustain life. Are there habitats that have experienced conditions similar to those on Earth when life emerged ,an abode of possible lifelong past. Mars and Europa(Jupiter’s icy moon)have been identified as the most relevant and immediate in the quest to answer these questions. Beyond Mars and Europa, every celestial body of interest appears to have its own geological history and every new discovery accentuates the overall complexity of our solar system. The exploration of Mars and Europa, and others, both remotely and in situ, is a central priority as part of NASA’s current and future goals for understanding the building of new worlds, the requirements for planetary habitats, and the workings of the solar system

Thermal vision, moisture content, and vegetation in the context of off-road mobile robots

This paper describes an initial investigation that shows the major impact that moisture and vegetation produce on a soil and how that effect may be measured using a thermal camera. In particular, those two variables influence how the soil compacts and, hence, the traversability of a vehicle. A broad set of experiments, under different weather conditions and with different soils, demonstrate that thermal properties derived from the thermal camera (i.e. thermal inertia) increase when moisture content of sandy soils increases. In addition to that, a relation is observed between thermal inertia and traversability (lower thermal inertia, worse traction; and vice versa). Another key behavior is noticed for vegetated soils, where a similar thermal inertia to wet sand is obtained but with only a third of moisture content. These results may be considered for maximizing traversability over sandy soils with higher thermal inertias, what eventually means higher compaction and safer routes. To the authors’ knowledge, this is the first work addressing the correlation between moisture content and vegetation, and the thermal properties of a soil using a light-weight thermal camera that can be mounted on a mobile robot

Mechanical Design of Cylindrical Track for Sideways Motion

Proceedings of 2008 IEEE International Conference on Mechatronics and Automatio