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 Systems Authors: Kano, Takeshi; Watanabe, Yuki; Ishiguro, Akio
    Autonomous 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 Environment Authors: Nokata, Makoto
    This 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 Device Authors: Dastoor, Sanjay; Cutkosky, Mark
    We 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 Actuator Authors: Kaminaga, Hiroshi; Tanaka, Hirokazu; Yasuda, Kazuki; Nakamura, Yoshihiko
    It 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 Motor Authors: Kumagai, Masaaki; Hollis, Ralph
    This 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 Magnets Authors: Marchese, Andrew; Rus, Daniela; Asada, Harry
    This 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) [1] 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 [2].

Micro/Nanoscale Automation III

  • Automated Parallel Cell Isolation and Deposition Using Microwell Array and Optical Tweezers Authors: Wang, Xiaolin; Sun, Dong
    Isolation and deposition of specific live cells with the high spatio-temporal resolution from the heterogeneous mixtures are of critical importance to a wide range of biomedical applications. In this paper, we report a robot-assisted cell manipulation tool with optical tweezers based on a uniquely designed microwell array. The whole automatic manipulation includes the target cell recognition, isolation, transportation and deposition. The microwell array is designed based on microfluidics technology, which allows the passive hydrodynamic docking of cells. Image processing technique is used to recognize the target cells based on the cell size or fluorescence label. After recognition, the target cells can be levitated from the microwell, and then assembled by multiple optical traps in parallel. The optically trapped target cells are then transported and deposited to the desired location precisely. Experiments are performed to demonstrate the effectiveness of the proposed cell manipulation approach.
  • Modeling and Compensation of Multivariable Creep in Multi-DOF Piezoelectric Actuators Authors: Rakotondrabe, Micky
    The scope of this paper is the modeling, identification and compensation of multivariable creep in piezoelectric actuators. Based on the inverse multiplicative scheme, we propose an approach to model and reduce the creep when the actuators have multiple degrees of freedom. The approach is simple to compute and easy to implement. The experimental results demonstrate the efficiency of the proposed approach on piezoelectric actuators.
  • High Speed Cell Patterning by Dielectrophoresis and On-Chip Fabrication of Microstructure Embedding Patterned Cells Authors: Yue, Tao; Nakajima, Masahiro; Kojima, Masaru; Fukuda, Toshio
    Constructing different patterns of cells and immobilizing these cells inside certain structures are very important issues for artificial tissue engineering. In this paper, we present methods of forming line pattern of yeast cells by dielectrophoresis (DEP) and immobilizing patterned cells by photo-crosslinkable resin. High speed cell pattering by DEP and on-chip fabrication of microstructure which contains patterned yeast cells is demonstrated. In order to applying DEP force for forming cell pattern, several novel microelectrodes are fabricated by Indium Tin Oxides (ITO) which are coated on the glass. The two kinds of DEP responses of yeast cell (W303) and the precise experimental parameters of them are confirmed. Based on negative DEP phenomenon, cell traps generated by microelectrode are demonstrated. Position control and transportation of yeast cells is performed by using cell traps. Besides, a cell trap matrix is fabricated and high speed cell pattering is performed. The experimental results show that the cell line patterns which contain hundreds of yeast cells can be formed by DEP within 1 second. The on-chip fabrication for arbitrary shapes of microstructures based on Poly Ethylene Glycol Diacrylate (PEG-DA) is reported. With the cell patterning by DEP and immobilizing by on-chip fabrication, microstructure which contains 3 lines of yeast cells is fabricated in the microfluidic channel, inside PEG-DA and NaCl solution.
  • Automatic Flocking Manipulation of Micro Particles with Robot-Tweezers Technologies Authors: Chen, Haoyao; Sun, Dong
    Flocking of micro-scaled particles, attracts increasing attention especially in cell engineering and drug industry, due to its potential application for particle manipulation with high throughput and productivity. This paper presents an efficient approach to flocking micro particles with robotics and optical tweezers technologies. All particles trapped by optical tweezers can be gradually moved towards a pre-defined region. The main contribution of this paper lies in a solution to achieve the flocking manipulation of particles in micro environments. A local potential function is proposed to avoid collision amongst particles and obstacles. Based on the relationship amongst laser power, particle movement velocity, and trapping force, saturation of velocities is employed to bound particle velocities. In this way, the flocking manipulation can be operated with efficiency and safety. Experiments on yeast cells with a robot-tweezers system are finally performed to verify the effectiveness of the proposed approach.
  • Development of the Auto Manipulation System towards the Single Cell Automatic Analysis Inside an Environmental SEM Authors: shen, yajing; Nakajima, Masahiro; Di, Pei; Yue, Tao; Kojima, Seiji; Homma, Michio; Fukuda, Toshio
    In this paper, an automatic system for single cell analysis inside an environmental scanning electron microscopy (ESEM) was proposed. Single yeast cell was put on an tungsten probe substrate inside ESEM. The endeffector for single cell analysis was fixed to an nanorobotic manipulator, which has three degrees of freedom, i.e. X, Y and Z translation. The real time images during the experiment can be observed by ESEM system in realtime. Therefore, the position of the endeffector and the single cell can be recognized by imaging processing. These position information were used as the feedback signal to control the movement of the nanorobotic manipulator. Finally, a single cell cutting experiment was performed to demonstrate the working mechanism of this system. Two types of cell pattern substrates were also designed and fabricated as the cell analysis chips for the automation single cell analysis in the future.
  • μ -Cell Fatigue Test Authors: Fukui, Wataru; Kaneko, Makoto; Sakuma, Shinya; Kawahara, Tomohiro; Arai, Fumihito
    A new concept of micro-cell fatigue test is proposed. By reciprocating a cell across the throat of a micro channel repeatedly, the dynamic deformation behavior of the cell is measured. We define a new index of fatigue characteristics of cells as the number of reciprocatory motion leading to a prescribed recovery ratio. The test system is composed of a piezoelectric (PZT) actuator, a high speed vision sensor and a micro channel with a throat. Preliminary experiments were conducted by using Red Blood Cells (RBCs). The result suggested that the activation level of a cell can be evaluated based on its fatigue characteristics.

Human Like Biped Locamotion

  • Regulating Speed and Generating Large Speed Transitions in a Neuromuscular Human Walking Model Authors: Song, Seungmoon; Geyer, Hartmut
    Although current humanoid controllers can rely on inverse kinematics or dynamics of the full humanoid system, powered prosthetic legs or assistive devices cannot, because they do not have access to the full states of the human system. This limitation creates the need for alternative control strategies. One strategy is to embed fundamental knowledge about legged dynamics and control in local feedback. In a previous paper, we have developed a control model of human locomotion which relies mostly on local feedback. The model can robustly walk at normal walking speeds. Here we extend this model to adapt to a wide range of walking speeds and to generate corresponding speed transitions. We use optimization of the model's control parameters and find key parameters responsible for steady walking between 0.8<i>ms<sup>-1</sup></i> and 1.8<i>ms<sup>-1</sup></i>, covering the range of speed at which humans normally walk. Using these parameters, we demonstrate speed transitions between the slow and fast walking. In addition, we discuss how the speed-dependent changes of the identified control parameters connect to biped walking dynamics, and suggest how these changes can be integrated in local feedback control.
  • Using Basin Ruins and Co-Moving Low-Dimensional Latent Coordinates for Dynamic Programming of Biped Walkers on Roughing Ground Authors: Suetani, Hiromichi; Ideta, Aiko; Morimoto, Jun
    Disturbance rejection is one of the most important abilities required for biped walkers. In this study, we propose a method for dynamic programming of biped walking and apply it to a simple passive dynamic walker (PDW) on an irregular slope. The key of the proposed approach is to employ the transient dynamics of the walker just before approaching the falling state in the absence of any controlling input, and to derive the optimal control policy in the low-dimensional latent space. In recent our study, we found that such transient dynamics deeply relates to the basin of attraction for a stable gait. By patching coordinates to such a structures in each Poincar¥'{e} surface and defining the reward function according to the survive time of the transient dynamics, we can construct a Markov Decision Process (MDP) for describing the PDW with external inputs, and we obtain optimal value and policy using a notion of dynamic programming (DP). We will show that the proposed method actually succeeds in controlling the PDW even if the degree of disturbance is relatively large and the dimensionality of coordinates is reduced to lower ones.
  • Spatio-temporal Synchronization of Periodic Movements by Style-phase Adaptation: Application to Biped Walking Authors: Matsubara, Takamitsu; Uchikata, Akimasa; Morimoto, Jun
    In this paper, we propose a framework for generating coordinated periodic movements of robotic systems with external inputs. We developed an adaptive pattern generator model that is composed of a two-factor observation model with style parameter and phase dynamics with a phase variable. The style parameter controls the spatial patterns of the generated trajectories, and the phase variable controls its temporal profiles. To validate the effectiveness of our proposed method, we applied it to a simulated humanoid model to perform biped walking behaviors coordinated with observed walking patterns and the environment. The robot successfully performed stable biped walking behaviors even when the style of the observed walking pattern and the period were suddenly changed.
  • A Convex Approach to Inverse Optimal Control and Its Application to Modeling Human Locomotion Authors: Puydupin-Jamin, Anne-Sophie; Johnson, Miles; Bretl, Timothy
    Inverse optimal control is the problem of computing a cost function that would have resulted in an observed sequence of decisions. The standard formulation of this problem assumes that decisions are optimal and tries to minimize the difference between what was observed and what would have been observed given a candidate cost function. We assume instead that decisions are only approximately optimal and try to minimize the extent to which observed decisions violate first-order necessary conditions for optimality. For a discrete-time optimal control system with a cost function that is a linear combination of known basis functions, this formulation leads to an efficient method of solution as a single quadratic program. We apply this approach to both simulated and experimental data to obtain a simple model of human walking paths. This model might subsequently be used either for control of a humanoid robot or for predicting human motion when moving a robot through crowded areas.
  • A Simple Bipedal Walking Model Reproduces Entrainment of Human Locomotion Authors: Ahn, Jooeun; Klenk, Daniel; Hogan, Neville
    Robotic studies have suggested a contribution of limit-cycle oscillation of the neuro-mechanical periphery to human walking by demonstrating stable bipedal robotic gaits with minimal actuation and control. As behavioral evidence of limit-cycle oscillation in human walking, we recently reported entrainment of human gaits to mechanical perturbations. We observed synchronization of human walking with mechanical perturbation only when the perturbation period was close to the original walking period. In addition, the entrainment was always accompanied by phase locking at the end of double-stance. A highly-simplified state-determined walker reproduced these salient features: 1) entrainment to periodic perturbations with a narrow basin of entrainment and 2) phase-locking at the end of double stance. Importantly, the model required neither supra-spinal control nor an intrinsic self-sustaining neural oscillator (like a rhythmic central pattern generator), which suggests that prominent features of human walking may stem from simple afferent feedback processes that produce limit-cycle oscillation of the neuro-mechanical periphery without significant involvement of the brain or rhythmic central pattern generators. One limitation of that model was that it entrained only to perturbations faster than the unperturbed walking period. In the study reported here, we modified the model to have two independent steps per stride. The revised model reproduced entrainment to perturbations both slower
  • Motion Primitives for Human-Inspired Bipedal Robotic Locomotion: Walking and Stair Climbing Authors: Powell, Matthew; Huihua, Zhao; Ames, Aaron
    This paper presents an approach to the development of bipedal robotic control techniques for multiple locomotion behaviors. Insight into the fundamental behaviors of human locomotion is obtained through the examination of experimental human data for walking on flat ground, upstairs and downstairs. Specifically, it is shown that certain outputs of the human, independent of locomotion terrain, can be characterized by a single function, termed the extended canonical human function. Optimized functions of this form are tracked via feedback linearization in simulations of a planar robotic biped walking on flat ground, upstairs and downstairs - these three modes of locomotion are termed &quot;motion primitives&quot;. A second optimization is presented, which yields controllers that evolve the robot from one motion primitive to another - these modes of locomotion are termed &quot;motion transitions&quot;. A final simulation is given, which shows the controlled evolution of a robotic biped as it transitions through each mode of locomotion over a pyramidal staircase.