Distributed Bio-inspired Humanoid Posture Control

This paper presents an innovative distributed bio-inspired posture control strategy for a humanoid, employing a balance control system DEC (Disturbance Estimation and Compensation). Its inherently modular structure could potentially lead to conflicts among modules, as already shown in literature. A distributed control strategy is presented here, whose underlying idea is to let only one module at a time perform balancing, whilst the other joints are controlled to be at a fixed position. Modules agree, in a distributed fashion, on which module to enable, by iterating a max-consensus protocol. Simulations performed with a triple inverted pendulum model show that this approach limits the conflicts among modules while achieving the desired posture and allows for saving energy while performing the task. This comes at the cost of a higher rise time.Comment: 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC

Overcoming Bandwidth Limitations in Wireless Sensor Networks by Exploitation of Cyclic Signal Patterns: An Event-triggered Learning Approach

Wireless sensor networks are used in a wide range of applications, many of which require real-time transmission of the measurements. Bandwidth limitations result in limitations on the sampling frequency and number of sensors. This problem can be addressed by reducing the communication load via data compression and event-based communication approaches. The present paper focuses on the class of applications in which the signals exhibit unknown and potentially time-varying cyclic patterns. We review recently proposed event-triggered learning (ETL) methods that identify and exploit these cyclic patterns, we show how these methods can be applied to the nonlinear multivariable dynamics of three-dimensional orientation data, and we propose a novel approach that uses Gaussian process models. In contrast to other approaches, all three ETL methods work in real time and assure a small upper bound on the reconstruction error. The proposed methods are compared to several conventional approaches in experimental data from human subjects walking with a wearable inertial sensor network. They are found to reduce the communication load by 60–70%, which implies that two to three times more sensor nodes could be used at the same bandwidth

Potentials in Social Environments

We develop and extend notions of potentials for normal-form games (Monderer and Shapley, 1996) to present a unified approach for the general class of social environments. The different potentials and corresponding social environments can be ordered in terms of their permissiveness. We classify different methods to construct potentials and we characterize potentials for specific examples such as matching problems, vote trading, multilateral trade, TU games, and various pillage games

Reactions of N-acetylcysteine adducts of aromatic (di)isocyanates with functional groups of organic molecules

Glutathione thiocarbamate conjugates of isocyanates play a key role in transport and final reactions of isocyanates in the human body by transcarbamoylation. N-acetylcysteine is the simplest model for thiocarbamate reactions. Therefore, transcarbamoylation of Nacetylcysteine adducts of p-tolylisocyanate (pTI-AcCys) and 4,4’-diisocyanatodiphenyl- methane (MDI(AcCys)2) with N-acetylcysteine methyl ester (thiolysis), morpholine (aminolysis), methoxyethanol (alcoholysis), and water (hydrolysis) has been studied in aqueous phosphate buffer solution and in dimethylacetamide (DMAc). Expected reaction products have been synthesised as reference compounds for HPLC-analysis. Concentrations of adducts and of reaction products were monitored by HPLC. Reaction rates and activation energies were determined for pTI in both media, reactions of MDI(AcCys)2 were run at one temperature only. Formation of insoluble reaction products and side reactions due to hydrolysis prevented in depth kinetic analysis of the reactions. Two regimes of reaction rate were observed in aqueous buffer, clear second order kinetics resulted in DMAc. In aqueous buffer (pH 7.4) a reactivity thiolysis > aminolysis > hydrolysis was found, while in DMAc aminolysis was faster than thiolysis. This can be explained by formation of thiolate at pH 7.4, which is not possible in anhydrous DMAc. Reactions of (MDI(AcCys)2) are by a factor of 2 to 4 faster than those of pTI-AcCys. p-Toluidine (pTA) was found in the aqueous system due to hydrolysis, while no 4,4’-methylene dianiline (MDA) could be detected. Under physiological conditions hydrolysis should compete with thiolysis under homogeneous conditions while ureas and carbamates should be much more stable against hydrolysis. No free isocyanate groups could be detected in any of the reactions. In conclusion the isocyanate moiety in thiocarbamates is readily transferred to sulfhydryl- and amino groups but not to aliphatic hydroxy groups. Under physiological conditions hydrolysis competes with these transcarbamoylation reactions. Formation of free isocyanate groups in analytical quantities was shown to be highly unlikely

A Novel Framework for a Systematic Integration of Pneumatic-Muscle-Actuator-Driven Joints into Robotic Systems Via a Torque Control Interface

In this paper, two different torque control approaches for PMA-driven (PMA = Pneumatic muscle actuator) revolute joints are presented and tested. In previous work controllers for PMA-driven robots are typically customized for the use on a specific robotic system. In contrast, the proposed controllers define a general control interface for every robot that is actuated by PMA-driven joints. It will be shown that controlling the torque of a PMA-driven joint enables the use of standard robotic motion control frameworks, because the torque represents the natural input of the robotic equation of motion. Therefore, both proposed torque control approaches are interconnecting PMAs and their challenging characteristics on the one hand and “conventional” motion control strategies for robots on the other hand. After a detailed discussion of two different torque control approaches, we show that a torque controller handles all characteristics and dynamics of a PMA-driven joint internally, which implies that only its bandwidth and its static torque characteristic must be taken into account for the design of the outer motion control loop. This feature simplifies the integration of PMA-driven joints in robotic systems enormously, as will be demonstrated by a design of a cascade-structured, flatness-based motion controller for an exemplary robot with one degree of freedom.BMWi, ZF4007503, Development of a PMA-driven Exoskeleton for the Upper Bod

Achieving near-zero particle generation by simplicity of design—A compliant-mechanism-based gripper for clean-room environments

Lab Automation facilitates high-throughput processes and improves reproducibility and efficiency while removing human action, primary source of contaminating particles. Handling poses a risk of contamination due to close contact with the objects. We propose a novel gripper (CrocoGrip) relying on compliant mechanisms to reduce the amount of contaminating particles generated by the gripper rather than preventing their emission, the latter being the common approach in current grippers. Using a structured design approach including simplified motion models and Finite Element Methods, we developed a novel gripper that is actuated by linear solenoids and purely relies on deformation for its motion. As a result, abrasive behavior and, therefore, the generation of particles is reduced without the need for additional sealing. We experimentally proved that the number of particles emitted by the CrocoGrip fulfills the demands of ISO14644 class 5. Due to the monolithic design of the CrocoGrip and, as a result, the need for few components, we achieve a simplicity of design, making cleaning, sterilization and maintenance easy, even for nonexperts. Furthermore, all parts but the two solenoids can be sterilized through autoclaving. The gripping is performed by utilizing the deformation energy of the compliant mechanism, making the gripping energy-efficient and safe. By using interchangeable jaws, the CrocoGrip was able to handle a microplate in SBS-standard, a 50 mL Falcon tube, and a Ø60 mm Petri dish using a robotic arm. CrocoGrip exploits the advantages of compliant mechanisms, especially for applications requiring clean-room environments. This approach of CM-based grippers enables an increase in the cleanliness of handling processes without an increase in system complexity of the gripper to facilitate the lab automation of highly sensitive processes, such as in tissue engineering