Zusammenfassung
Der Beitrag gibt einen Überblick der Forschung an voll aktuierten, humanoiden Laufmaschinen. Neben einer allgemeinen Einführung wird ein kurzer Abriss der Geschichte humanoider ...Roboter gegeben. Die bekanntesten Systeme werden nach Forschungszentren gegliedert vorgestellt. Aufbauend auf einer kurzen Einführung zu grundlegenden Aspekten der Dynamik des zweibeinigen Gehens werden die am weitesten verbreiteten Strategien zur Laufregelung dargestellt. Am Ende des Artikels wird auf einige offene Fragestellungen eingegangen.
Abstract
This paper surveys research on fully actuated humanoid walking machines. After a general introduction we briefly review the history of humanoid robots. We present the most prominent examples of current biped robots. Following a brief introduction of basic aspects of the dynamics of biped robots we review popular walking control methods. A brief review of open research questions concludes the paper.
Zusammenfassung
Dieser Beitrag beschreibt ein System zur Regelung redundanter zweibeiniger Roboter. Das hierarchisch angelegte System erzeugt aus groben Vorgaben zum gewünschten Gang in Echtzeit eine ...stabile Laufbewegung. Die stabilisierende Regelung kompensiert Modellfehler, externe Kräfte und Bodenunebenheiten. Durch Nutzung kinematischer Redundanzen können erforderliche Gelenkwinkelgeschwindigkeiten minimiert und die Gefahr des Rutschens reduziert werden. In dem Artikel wird die von uns für experimentelle Arbeiten entwickelte Laufmaschine Lola beschrieben und ein Überblick der mit diesem Roboter erzielten experimentellen Ergebnisse gegeben.
Abstract
This paper describes an approach to controlling redundant biped robots. A hierarchichal control system generates biped walking in real-time from simple high-level commands. The stabilizing control compensates modelling errors and external forces and allows the robot to walk over uneven terrain. Both the required joint speeds and the risk of slipping are minimized by exploiting redundant degrees of freedom. We also briefly describe our biped robot Lola used in the experimental results outlined at the end of the article.
In this paper we describe an event-based walking control system for biped robots. Classically, the control of biped robots has been separated into walking pattern generation and stabilizing control. ...While this is an effective strategy in well-known environments, walking in rough, unmodelled terrain can easily destabilize the system. Findings from neurobiology suggest that gait generation in animals and humans is strongly linked to sensory signals indicating certain events in the gait cycle. We therefore propose an event-based controller that triggers phase transitions based on the sensed walking state instead of only relying on time-based reference trajectories. We have implemented the proposed approach on our humanoid robot Lola. We present simulations and experimental results demonstrating the effectiveness of the approach when walking over unknown obstacles.
Zusammenfassung
Der Beitrag beschreibt den mechatronischen Entwurf und die Laufregelung des humanoiden Roboters Lola. Seine charakteristischen Merkmale sind die redundante Kinematik, der extreme ...Leichtbau, Gelenkantriebe mit bürstenlosen Motoren und eine Elektronik-Architektur mit dezentraler Gelenkregelung. Ein Schwerpunkt im Entwurf war die Optimierung der Massenverteilung zur Verbesserung der Systemdynamik. Die Referenztrajektorien werden in Echtzeit berechnet und durch eine stabilisierende Regelung auf Basis hybrider Kraft-/Positionsregelung modifiziert. Das Regelungssystem ermöglicht sowohl schnelles Gehen als auch die für das autonome Gehen erforderliche Anpassung der Laufrichtung und -geschwindigkeit während des Gehens.
Abstract
This paper describes the mechatronic design and walking control of the humanoid robot Lola. The robot is characterized by a redundant kinematic configuration, an extremely lightweight design, joint actuators with brushless motors and an electronics architecture using decentralized joint control. Special emphasis was put on an improved mass distribution to achieve good dynamic performance. Reference trajectories are generated in real-time and modified by a stabilizing control system based on hybrid force/position control with an inner joint position control loop. The control system enables fast walking as well as on-line modification of walking direction and walking speed required for autonomous locomotion.
In adult male rats, the expression of the neuropeptide galanin and its co-localization with the c-Jun transcription factor and the NADPH-diaphorase, the marker enzyme for the nitric oxide synthase ...(NOS), was investigated by immunohistochemistry in axotomized neurons following unilateral stereotaxic transection of the (a) mamillo-thalamic tract, (b) medial forebrain bundle, (c) fimbria fornix bundle and (d) sciatic nerve. This surgical procedure resulted in axotomy of neurons of (a) mamillary ncl. (MnM), (b) substantia nigra compacta (SNC) and paraventricular ncl. of thalamic (PF) neurons, (c) medial septum (MS) and vertical diagonal band of Broca (VDB), and (d) sciatic motoneurons and dorsal root ganglia (DRG). In all of these axotomized neuronal subpopulations, expression of c-Jun appeared between 24 and 36 h post-axotomy and persisted on substantial levels for 15 days in the SNC and for 30–50 days in the MnM, PF, MS, VBD, sciatic DRG and motoneurons. Expression of galanin was seen in axotomized MnM, MS and DRG, but not in SNC, PF and sciatic motoneurons. Galanin-immunoreactivity (IR) appeared between 3 and 5 days after nerve fiber transection and persisted up to 50 days in the MnM, MS and DRGs. The cytoplasmic galanin-IR was almost completely restricted to those neurons showing a nuclear c-Jun expression. Moreover, galanin expression showed a long-lasting co-localization with those neurons that exhibited an increased NADPH-diaphorase reactivity in the MnM and DRG or a residual NADPH-diaphorase reactivity in MS post-axotomy. Very similar to galanin, NADPH-diaphorase was not affected by axotomy in the SNC, PF or sciatic motoneurons. Our findings suggest a common mechanism for galanin and NOS (NADPH-diaphorase activity) expression. Since the galanin promotor contains an AP-1 binding site, c-Jun might trigger the lasting induction of galanin in NOS-positive central neurons that survive the axotomy-evoked injury.
Gastric cancer mortality is second only to lung cancer, and its prognosis is dismal. Using surface-enhanced laser desorption/ionization-time-of-flight mass spectrometry, we previously identified a ...single best mass, which could separate gastric cancer from patients without cancer, with a sensitivity of 89.9% and a specificity of 90%. Using protein liquid chromatography systems with various chromatography media and MS/MS analysis, we were able to identify thrombin light chain A, a proteolytic fragment of prothrombin, as the single best mass for early detection of gastric cancer patients. These findings indicate that disturbances in the coagulation-system are early events in gastric cancer biology and that a decrease or loss of thrombin light chain A, which we termed negative serum protein profiling, may contribute to the diagnosis of cancer patients. Keywords: gastric • carcinoma • stomach • SELDI • biomarker • thrombin • thrombosis • diagnosis
Bio-inspired Robot Locomotion Buschmann, Thomas; Trimmer, Barry
Neurobiology of Motor Control,
2017, 2017-09-05
Book Chapter
Bio‐inspired robots are driving robot engineering in a variety of new directions and are expected to find particular success operating in natural environments. The most robust and adaptable robots ...are not only bio‐inspired but also “bio‐informed” in that they exploit fundamental biological principles of locomotion and control. A major challenge in both rigid and soft robotics is better understanding of how control tasks should be distributed between centrally generated commands and peripheral mechanical responses. This chapter reviews mechanism design, sensing, actuation and control approaches in legged robots with skeletal structures. Every legged robot is underactuated, since, due to either ground or foot compliance, the foot‐ground contact always has finite stiffness, and there is no actuator to control contact elastic deformation. Next, the chapter talks about soft robots that they are resistant to damage by sudden impact, can change shape and size, and can be made intrinsically safe for use in human and natural environments.
In order to achieve fully autonomous humanoid navigation, environment perception must be both fast enough for real-time planning in dynamic environments and robust against previously unknown ...scenarios. We present an open source, flexible and efficient vision system that represents dynamic environments using simple geometries. Based only on onboard sensing and 3D point cloud processing, it approximates objects using swept-sphere-volumes while the robot is moving. It does not rely on color or any previous models or information. We demonstrate the viability of our approach by testing it on our human-sized biped robot Lola, which is able to avoid moving obstacles in real-time while walking at a set speed of 0.4m/s and performing whole-body collision avoidance.
Identification of Mdm2 and JNK as proteins that target degradation of wt p53 prompted us to examine their effect on mutant p53, which exhibits a prolonged half-life. Of five mutant p53 forms studied ...for association with the targeting molecules, two no longer bound to Mdm2 and JNK. Three mutant forms, which exhibit high expression levels, showed lower affinity for association with Mdm2 and JNK in concordance with greater affinity to p14(ARF), which is among the stabilizing p53 molecules. Monitoring mutant p53 stability in vitro confirmed that, while certain forms of mutant p53 are no longer affected by either JNK or Mdm2, others are targeted for degradation by JNK/Mdm2, albeit at lower efficiency when compared with wt p53. Expression of wt p53 in tumor cells revealed a short half-life, suggesting that the targeting molecules are functional. Forced expression of mutant p53 in p53 null cells confirmed pattern of association with JNK/Mdm2 and prolonged half-life, as found in the tumor cells. Over-expression of Mdm2 in either tumor (which do express endogenous functional Mdm2) or in p53 null cells decreased the stability of mutant p53 suggesting that, despite its expression, Mdm2/JNK are insufficient (amount/affinity) for targeting mutant p53 degradation. Based on both in vitro and in vivo analyses, we conclude that the prolonged half-life of mutant p53 depends on the nature of the mutation, which either alters association with targeting molecules, ratio between p53 and targeting/stabilizing molecules or targeting efficiency.
Selective tasks such as harvesting or spraying of single crops are a promising research topic in agricultural automation. Inspired by industrial production, an obvious approach is to use robot ...manipulators in greenhouses and orchards. To exploit the potential of redundant manipulators in particular, advanced motion planning algorithms are needed. While harvesting, a new trajectory for every fruit has to be planned. Although the scenario is similar for every fruit, it is unique for each harvesting sequence. In this paper we present an efficient online planning approach which takes advantage of a simplified environment model. However, the generated trajectory is not optimal in general w.r.t. joint velocities or might even be unfeasible. Thus, we introduce an optional global offline optimization scheme which is able to find optimal trajectories in a few seconds and takes advantage of the heuristic planning as initial guess. We apply the proposed scheme to a 9-DOF agricultural manipulator for sweet-pepper harvesting and evaluate our method by extensive tests with fruit positions based on real measurements.
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