Technical session talks from ICRA 2012
TechTalks from event: Technical session talks from ICRA 2012
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Novel Actuation Technologies
SheetBot: Two-Dimensional Sheet-Like Robot As a Tool for Constructing Universal Decentralized Control SystemsAutonomous decentralized control is a key concept for the realization of highly adaptive behavior. However, universal design of autonomous decentralized control that ensures rich adaptability is still lacking. In this study, we tackle this problem through the development of a two-dimensional sheet-like robot, SheetBot. The SheetBot is a suitable model system for the establishment of universal design principles for autonomous decentralized control, because it can bend reasonably to the circumstances encountered due to its large surface area, and also because its applications are widely expected. To realize highly adaptive locomotion with SheetBot, we are inspired by the decentralized control scheme of the scaffold-based locomotion of snakes. We extend this design scheme to a two-dimensional bodily structure on the basis of a continuum model. Simulation results show that SheetBot can locomote on various kinds of irregular terrain with minimal control inputs by implementing the proposed autonomous decentralized control scheme.
Deformable Robot Maneuvered by Magnetic Particles for Use in a Confined EnvironmentThis paper presents an advanced locomotion method that produces non-slipping motion in digestive organs and the abdominal cavity. New movement principle of the robot, which has a soft and deformable body that can move through a confined space is proposed. The mechanism of a toy water snake is applied to this principle. Magnetic particles inside the water balloon are affected by the external magnetic field and exert an internal pressure. We construct an experimental model to verify the proposed principle, the sliding movement is measured using the model. Confirmatory experiments of movement are conducted in the two sheets that imitated internal organs.
Design of Dielectric Electroactive Polymers for a Compact and Scalable Variable Stiffness DeviceWe present the design, analysis, and experimental validation of a variable stiffness device based on annular dielectric electroactive polymer (EAP) actuators. The device is based on a diaphragm geometry, which partially linearizes the viscoelastic response of acrylic dielectrics, providing voltage- controlled stiffness without high damping losses. Multiple diaphragms can be connected in a single device to increase stiffness or provide custom stiffness profiles. The geometry is analyzed to determine the relationship among force, displacement and voltage. A single-layer diaphragm was constructed and tested to validate the concept, demonstrating up to 10x change in stiffness.
Viscous Screw Pump for Highly Backdrivable Electro-Hydrostatic ActuatorIt is widely acknowledged that the actuator's intrinsic backdrivability is important in realizing a force sensitive behavior. It is desirable to realize such actuator with electric motor that is advantageous from power-to-weight ratio and controllability point of view. Electro-Hydrostatic Actuator is a type of hydraulic actuators that can realize high backdrivability by reducing transmission friction and by providing dynamics decoupling with an implicit serial damper. To farther enhance the backdrivability of a EHA, a pump with minimum static and Coulomb friction is necessary. In this paper, we introduce an EHA with viscous screw pump that minimizes static and Coulomb friction by eliminating the mechanical contact between pump components. Viscous screw pumps also have the advantage that there is no pulsation in pressure due to the continuity of the force transmission from the rotor to the fluid. The property of the actuator, including pulsation performance and impedance control performance were evaluated on a prototype of EHA with a viscous screw pump.
Development and Control of a Three DOF Planar Induction MotorThis paper reports a planar induction motor (PIM) that can output 70 N translational thrust and 9 Nm torque with a response time of 10 ms. The motor consists of three linear induction motor (LIM) armatures with vector control drivers and three optical mouse sensors. First, an idea to combine multiple linear induction elements is proposed. The power distribution to each element is derived from the position and orientation of that element. A discussion of the developed system and its measured characteristics follow. We implemented a PIM with position and orientation tracking control. Experiments were carried out using the system. First, response of individual LIM was measured, and we confirmed that it could output thrust up to 40 N in a response of 10 ms. It also showed linearity. Then, force/torque output of the integrated PIM was confirmed. Using the PIM and the position sensing system, the position feedback control was performed. The results were presented by graphs on the paper and by movie included in accompanying video. These experimental results highlights the potential of direct drive features of the PIM.
Controlling the Locomotion of a Separated Inner Robot from an Outer Robot Using Electropermanent MagnetsThis paper presents the design, modeling, and experimental verification of a novel, programmable connection mechanism for robots separated by a surface. The connector uses electropermanent magnets (EPMs)  to establish a continuum of clamping force between the robots, enabling the motion of one robot to slave the other during a variety of maneuvers. The authors design a novel, solid-state EPM arrangement capable of generating up to an estimated 890N of clamping force under environmental loading conditions. A relationship between geometric and environmental variables and connection assembly performance is first modeled and subsequently experimentally characterized. By implementing these connectors in a custom manufactured pair of assembly robots, the authors demonstrate the connection assembly and magnetizing hardware can be compactly fit within an autonomous robot application. We offer this mechanism as a repeatable, easily-automated alternative to robotic systems that depend on mechanic means to regulate clamping force .