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Learning to adapt one’s gait with environmental changes plays an essential role in locomotion of legged robots which remains challenging for constrained computing resources and energy budget, as in the case of edge-robots. Recent advances in bio-inspired vision with dynamic vision sensors (DVS) and associated neuromorphic processing can provide promising solutions for end-to-end sensing, cognition and control tasks. However, such bio-mimetic closed-loop robotic systems based on event-based visual sensing and actuation in the form of spiking neural networks (SNN) have not been well explored. In this work, we program the weights of a bio-mimetic multi-gait central pattern generator (CPG) and couple it with DVS-based visual data processing to show a spike-only closed-loop robotic system for a prey-tracking scenario. We first propose a supervised learning rule based on stochastic weight updates to produce a multi-gait producing Spiking-CPG (SCPG) for hexapod robot locomotion. We then actuate the SCPG to seamlessly transition between the gaits for a nearest prey tracking task by incorporating SNN based visual processing for input event-data generated by the DVS. This for the first time, demonstrates the natural coupling of event data flow from event-camera through SNN and neuromorphic locomotion. Thus, we exploit bio-mimetic dynamics and energy advantages of spike-based processing for autonomous edge-robotics.

This article proposes a data-driven multiobjective evolutionary interval type-2 fuzzy-logic system (IT2FLS) learning approach that considers both system performance and rule interpretability. One characteristic of the evolutionary learning framework is that the IT2FLS structure is incrementally generated instead of searching from an initially huge grid-type rule base, which significantly reduces the parameter search space. Another one is that a new constrained objective function is proposed to improve the distinguishability of the generated interval type-2 fuzzy sets (FSs) without restricting them to be evenly distributed. Because of the tradeoff between system performance and interpretability, a new multiobjective ant colony optimization (ACO) algorithm is proposed to optimize the IT2FLS parameters and improve optimization performance. The evolutionary IT2FLS learning approach is applied to control a real wall-following hexapod robot. The approach shows the advantages of model-free design and interpretability and robustness to noise in the evolved type-2 fuzzy rules. Simulations with performance comparisons and experiments in controlling a real robot show the advantages of the learning approach.

The increasing application requirements of multilegged walking robots in outdoor environments pose new challenges regarding the design of their teleoperation systems. Some of these challenges arise from the multiple degrees of freedom of the telerobotic system and nonpassive exogenous disturbance. Herein, a novel control system based on a dual-master/single-slave bilateral haptic teleoperation framework using a semiautonomous strategy for hexapod robots walking on deformable rough terrains is proposed. In this teleoperation system, the body velocities and postures of the hexapod robot are determined according to the positions of two haptic master robots. The proposed teleoperator includes a time-domain passivity control approach to compensate for the system's potential nonpassivity induced by the contact slippage between the foot and the ground. Furthermore, a posture-level bilateral controller is designed to overcome the unpredictable posture vibration. Information about the velocity loss and posture error is displayed to the human operator in the form of haptic force. In the underlying controller of the slave robot, a foot-force optimization algorithm is developed to improve the local autonomy of the teleoperation system. Furthermore, the stability of the system is demonstrated by its passivity. Experimental results indicate that the proposed controllers can provide a stable and transparent bilateral haptic teleoperation system for a hexapod robot under environmental perturbations.

Locomotion in animals provides a model for adaptive behavior as it is able to deal with various kinds of perturbations. Work in insects suggests that this evolved flexibility results from a modular architecture, which can be characterized by a recurrent neural network allowing for various emerging attractor states. Whereas a lower control-level coordinates joint movements on a short timescale, a higher-level handles action selection on longer timescales. Implementation of such a control system on a walking hexapod robot was able to deal with various walking patterns including disturbances such as uneven terrain or loss of a leg. Here, we propose a cognitive expansion to the adaptive control system that allows dealing with novel challenging situations. This approach makes use of an internal simulation-based planner that is triggered when the model-free controller fails to recover from an unstable pose. Using a grounded internal body model, the planner then tries, in internal simulation, different solutions out of context, and thus, proposes a new plan to be executed on the real robot. We demonstrate the feasibility of this control approach for walking over terrain with uncertain footholds in three scenarios.

ABSTRACT OF THE THESISLocomotion performance of hexapod robots on rough substrates and the influence of leg compliancebyAmartya Bhattacharyya Master of Science in Engineering Sciences (Mechanical Engineering)University of California San Diego, 2019Professor Nicholas Gravish, ChairHexapod Robots are a complex system where six legs are connected to the main body which acts as a support frame. A lot of research has been performed in this field from the study of six legged insects to present day implementations where the robot uses its own decision making network. The motivation for this field are the various advantages that hexapedal robots provide like; Obstacle climbing capability, omnidirectional motion, variable geometry, stability, access to uneven terrain etc. At the same time they also have many disadvantages like low energy efficiency, low speeds, complexity of operation and design and especially a lot of attention has to be given to path and gait planning. Therefore, in this paper wexiiuse an open loop platform for our robot and test the performance on simulated rough substrates. Using the results we propose a compliant leg design which will improve the performance while maintaining the stability. We compare the new design with solid legs to quantify the gain. And also test for the shear force limits to make sure the design is ready to be tested on a robot for full length runs. With a goal to utilize the new design and simplify the requirements of complicated neural networks for gait planning.

The vehicle motion signals cannot be replicated using the simulation-based motion platform (SBMP) because of the workspace limitations. The motion cueing algorithms (MCAs) are introduced to reproduce the motion sensation for the driver of the SBMP same as the real vehicle while keeping the SBMP inside the limitations. The optimal MCA was developed to decrease the human motion sensation error between the real vehicle and the SBMP user based on the human vestibular model using the linear quadratic regulator method. However, the inverse acceleration kinematics model of the SBMPs are not considered in developing optimal MCA in order to control the position, velocity and acceleration of actuators. The lack of inverse acceleration kinematics consideration inside the optimal MCA causes the poor consumption of the SBMP's workspace. In this paper, the new optimal MCA based on the inverse acceleration kinematics problem of the SBMP is designed and developed to regenerate the more realistic motion sensation. The validation of the new optimal MCA is performed using Simulink/MATLAB. The outcomes show that using the new optimal MCA will lead to better motion sensation with less wrong motion signals compared with the existing optimal MCAs

A novel legged robot with 6 limbs driven by 20 proprioceptive motors, named SDUHex, is proposed in this letter. The limbs located at the middle of the robot can work as manipulators or locomotors. The topology design of the multi-mode robot is introduced and the kinematics and dynamics of the robot leg is analysed. A hierarchical optimized whole body controller with virtual model active compliance, called VM-WBC, is proposed. This control method unified the foot locomotion and arm operation. The terrain adaptation strategy is proposed to improve the non-flat terrain passability. A series of locomotion and operation experiments are carried out on SDUHex to test the designed robot and control method. Robust locomotion of the robot is verified by lateral impact recovery and slope terrain adaptation experiments. Arm operation of the robot including single-arm pushing and dual-arm picking are experimented to highlight the novel multiplexing function of the robot limbs.

Aufgrund der komplexen Supply-Chains in modernen Produktionsanlagen und Logistikzentren besteht in der Intralogistik zunehmender Bedarf an flexiblen Transportmöglichkeiten. Während der Gütertransport in diesen Einrichtungen bisher meist klassisch durch Fließbänder erfolgt, könnten in Zukunft andere Systeme die Intralogistik bestimmen. Eine mögliche Variante wären vollautonome Roboter-Transportameisen, die, wie das Vorbild der echten Ameisen im Schwarm kooperativ Lasten transportieren. In dieser Bachelorarbeit wird eine von drei Komponenten einer solchen Robo-Ant, das Exoskelett, ausgearbeitet. Dieses bildet die Grundstruktur der Robo-Ant, an der die Beine und der Kopf, welche in separaten Arbeiten konstruiert werden, befestigt werden. Um ein Konzept für das Exoskelett zu entwickeln, wurde die Literatur nach ähnlichen Projekten durchsucht und deren Konstruktionen vorgestellt und analysiert. Dabei wurde festgestellt, dass für Transportaufgaben zurzeit vor allem auf Roboter mit Rädern oder vier Beinen gesetzt wird. Von sechsbeinigen Robotern existieren jedoch einige Prototypen. Im Projektteam wurden gemeinsam die konstruktiven Anforderungen an die Robo-Ants erarbeitet und ein Grobkonzept wurde erstellt. Anschließend folgte im Zuge dieser Arbeit die Konstruktion des Exoskeletts. Es wurde eine leichte, stabile Grundstruktur geschaffen, die die zu tragenden Lasten aufnimmt und die verbaute Elektronik im Inneren der Ameise schützt. Elektronikkomponenten wurden beispielhaft ausgewählt und eingeplant. Weiters wurde die Konstruktion durch den Einsatz von Festigkeitssimulationen optimiert und überprüft. Im Zuge der Ausarbeitung wurde auch auf die verschiedenen möglichen Materialien und Fertigungsmethoden für die konstruierten Teile Augenmerk gelegt. Zuletzt erfolgte für das erarbeitete Konzept eine Kostenrechnung und die Aufstellung der Bauteilmassen. Neben den Konstruktionsdateien, Zeichnungsableitungen, sowie Kosten- und Gewichtsrechnung lässt sich als Ergebnis der Arbeit eine Aussage über die Zukunftsfähigkeit der Verwendung von Roboter-Transportameisen in der Intralogistik treffen. Als größter Nachteil dieses Konzepts wurden die hohe Komplexität und die hohen Kosten identifiziert, welche einen Einsatz als reines Transportsystem unwahrscheinlich machen, da in der Logistikbranche ein hoher Kostendruck herrscht. Allerdings könnten die Robo-Ants aufgrund ihrer Vorteile, wie die Möglichkeit des Einsatzes in unwegsamen Gelände und ihrer Flexibilität auch in anderen Bereichen vielversprechend eingesetzt werden, zum Beispiel bei Inspektionsaufgaben in gefährlichen Bereichen. Due to the complex supply chains in modern production facilities and logistics centers, there is an increasing demand for flexible transport options in intralogistics. While the transport of goods in these facilities has so far mostly been carried out classically by assembly lines, other systems could determine intralogistics in the future. One possible variant would be fully autonomous robot transport ants, which, like the role model of real ants, cooperatively transport loads in a swarm. In this bachelor thesis, one of three components of such a Robo-Ant, the exoskeleton, is elaborated. It forms the basic structure of the Robo-Ant, to which the legs and the head, which are constructed in separate work, are attached. To develop a concept for the exoskeleton, the literature was searched for similar projects and their designs were presented and analyzed. It was found that for transportation tasks, robots with wheels or four legs are currently the main choice. However, some prototypes of six-legged robots exist. Within the project team design requirements for the Robo-Ants and a rough concept were drawn up. Subsequently, the construction of the exoskeleton followed in the course of this bachelor thesis. A lightweight, stable basic structure was created to support the loads to be carried and to protect the installed electronics inside the ant. Electronic components were selected and planned in an exemplary manner. Furthermore, the design was optimized and verified by using strength simulations. In the course of the thesis, attention was also paid to the various possible materials and manufacturing methods for the designed parts. Finally, a cost calculation was carried out for the developed concept and the component masses were listed. In addition to the design files, drawing derivations, as well as cost and weight calculations, a statement about the future of robot transport ants in intralogistics can be made as result of the bachelor thesis. The greatest disadvantage of this concept was identified as the high complexity and the high costs, which makes it unlikely to be used as a pure transport system since there is high cost pressure in the logistics industry. However, due to their advantages such as the possible usage in rough terrain and their flexibility, the Robo-Ants could also be used promisingly in other areas, for example in inspection tasks in hazardous areas.

BackgroundIt is challenging to determine the orthogonality of radiographs in daily clinical practice. The purpose of this study was to show the usefulness of an additional foot ring which might determine the orthogonality of postoperative radiographs for the parameter measurement of hexapod external fixator.MethodsWe retrospectively analyzed 81 consecutive trauma patients with tibial shaft fractures treated by the hexapod external fixator at our institution from September 2014 to July 2019. Starting in March 2016, the postoperative radiographs for parameter measurement were obtained under the control of an additional foot ring. The final data consisted of 47 patients in traditional radiographs (Group I) and 34 patients under the control of foot ring during the radiographic process (Group II). The demographic data, original postoperative deformities, residual deformities after final correction, number of repeated radiographs after the first postoperative radiographs, time to the satisfactory reduction achieved, and external fixation time in all patients were documented and analyzed. The Johner–Wruhs criteria were used for the final clinical outcomes evaluation at the last clinical visit.ResultsSatisfactory reduction and bone union were achieved in all patients. There were no statistical significances between the two groups in the demographic data, original postoperative deformities, residual deformities after final correction, external fixation time, and the final clinical outcomes (P > 0.05). The mean number of repeated radiographs after the first radiographs (1.4 times) and mean time to the satisfactory reduction achieved (3.3 days) in patients with an additional foot ring used were all less than those without foot ring (2.4 times, 5.3 days) (P ConclusionsThe additional foot ring is a practical device to ensure the orthogonality of postoperative radiographs for the hexapod external fixator parameter measurement. Radiation exposure, duration of deformity correction, and cost for patients might be reduced due to the less repeated radiographs with the wrong position.

Characterization of terrain in real time allows autonomous legged robots to modify their gait to better suit their environment and recognize hazardous conditions. We present a novel approach for terrain classification for legged robots with passively compliant components, in which terrain information is gathered by measuring component deflection during operation by means of low cost Hall effect magnetometers and embedded magnets. The effectiveness of this approach is demonstrated on a hexapod robot designed to operate in the surf zones of beaches. Datasets of sensor measurements corresponding to three types of granular terrain are collected in both a laboratory and outdoor beach environment, and are used to train support vector machine (SVM) classifiers. Results show that, using time domain features of measurements from each leg, a mean accuracy of 99.3% and 92.4% through 10-fold cross-validation can be achieved for the laboratory and beach datasets, respectively. For the beach dataset, this accuracy is found to be slightly greater than for a classifier trained on measurements from an on-board inertial measurement unit (IMU) (91.6%), while an accuracy of 95.1% can be achieved by combining the information from both sensor modalities as inputs to a single classifier. The effect of the Earth’s magnetic field on the measurements and considerations for data collection are also discussed.

The hexapod manipulator is the most common motion platform, which is widely used as a simulation-based motion platform (SBMP). As the hexapod manipulator has a limited workspace, it is not physically possible to regenerate the real vehicle motion signals using the SBMP. The motion cueing algorithm (MCA) is responsible for regenerating a realistic vehicle motion sensation for the user when the SBMP operates within its physical and dynamical limitations. Recently, model predictive control (MPC) has been introduced to extract the optimal input motion signals while considering the SBMP limitations in the Cartesian coordinate space, which leads to a linear time-invariant (LTI) MPC-based MCA methods. Unfortunately, the existing LTI MPC-based MCA methods are still not able to consider the parameters of the SBMP’s hexapod mechanisms inside their models. In general, the current studies only consider the constraints in the Cartesian coordinate system of the hexapod mechanism, instead of its design parameters. This consideration results in a poor usage of the hexapod workspace due to the conservative assumptions; consequently, the SBMP users do not experience realistic motions. The main contribution of this article is to take the SBMP’s physical limitations into account in the MPC model such that more precise motion cues can be extracted for the users. A linear time-varying (LTV) MPC-based MCA method is designed for the first time in this article to consider the parameters of the hexapod mechanism in the MPC model. The proposed model (LTV MPC-based MCA) is validated using the MATLAB software, and the results depict better motion sensation with more accurate motion signals as compared with those from the existing LTI MPC-based MCA methods.

The use of hierarchical networks in motor pattern generation in hexapod robots and in insect movement provides ways to understand and control both systems. In this paper we consider the Central Pattern Generator (CPG) of insect movement consisting of six coupled neurons developed by Ghigliazza and Holmes (2004) that produces the global leg coordination pattern. We provide a detailed study of the possible gaits generated by the CPG through different numerical techniques recently developed for the study of small networks, which allow us to consider the complete model without any simplification. We combine the analysis of isolated neurons (using several three dimensional parameter spaces) to give a roadmap of the dynamics of the neurons involved, lateral phase lag plots to show the convergence and transitions towards particular patterns and a quasi-Monte Carlo sweeping method to describe different pattern routes in the parametric phase space. In all of our studies we have found the same final result: most of the observed patterns follow routes that lead to the stable tripod gait. We obtain several routes made of symmetrical patterns, but despite considering mainly a symmetric leg CPG we detect non-symmetrical patterns that provide (minor) routes present in the model. The bifurcations of the main pattern routes detected in the parameter space are studied in detail using continuation techniques. This study reveals the bifurcations that create and destroy the different routes and how for large values of some parameters only the tripod gait is present. Based on the symmetric case, a preliminary study of asymmetric configurations is done revealing the robustness of the already located patterns and routes. Due to the relevance of the tripod gait, and since more parameters are included in this study, we introduce an algorithm to locate the limit of the tripod gait in the parameter space, which shows that there is a large three parametric region where the tripod pattern is ubiquitous and highly dominant in rapidly moving insect regimes.

U ovom radu je prikazano kako napraviti robota. Takvi roboti mogu biti različitog tipa pa je važno napomenuti da je ovo heksapod, odnosno pauk sa šest nogu. Pokazano je kako izraditi konstrukciju nogu da bude kompatibilna sa motorima, kako povezati zglobove te kako ih povezati sa tijelom. U drugom dijelu se nalaze proračuni za statički moment nogu kada su tri noge u zraku. Proračunata je inverzna kinematika koja je potrebna za kontrolu noge te je izračunata potrebna struja za robota. U trećem dijelu je objašnjeno koje mikroprocesore koristiti i zašto njih. Također je objašnjeno kako riješiti problem sa velikim strujama i koje motore koristiti. Kako riješiti problem sa PCA9685 koji ne može dati dovoljno struje svim motorima. Zadnji dio je kontrola robota. Kod je pisan u Arduino IDE. Objašnjeno je kako povezati više mikroprocesora, kako iskoristiti websockete i zašto, te kako izraditi jednostavnu internet stranicu u Javascriptu. Također je objašnjeno kako kontrolirati noge pauka i kako iskoristiti inverznu kinematiku za to. In this thesis, it is shown how to make a Spider robot. Spider robots can be different so it is important to say this is a hexapod, a spider robot with six legs. The design of the robot is shown how to create legs to be compatible with motors, how to connect different parts of the legs and how to connect them with the body. In the second part are shown calculations for static torque of the legs when three of the legs are in the air. Inverse kinematics is also shown because it is needed for the control of the robot. And some simple calculations for the current that is needed to power the robot. The third part is electronics, what microprocessors are used and why them. How to solve the problem with too big currents and what motors are used. How to solve the PCA9685 problem with currents is also addressed. The last part is control of the robot. The code is written in Arduino IDE. Connecting multiple microprocessors, how to use WebSockets and why, and how to create a simple webpage in Javascript. Details around controlling movements of spider legs and how to use inverse kinematics for it.

Fragestellung: Bei Tibiafrakturen mit kurzem distalem gelenktragendem Segment kann mit einem Ringfixateur, z.B. Taylor Spatial Frame (TSF) eine Vollbelastung bei zeitgleicher freier Beweglichkeit des Sprunggelenks ermöglicht werden. Im klinischen Alltag zeigen sich Lockerungen bis hin zum Versagen [zum vollständigen Text gelangen Sie über die oben angegebene URL]

Nowadays many robotic systems are developed with lot of innovation, seeking to get flexibility and efficiency of biological systems. Hexapod Robot is the best example for such robots, it is a six-legged robot whose walking movements try to imitate the movements of the insects, it has two sets of three legs alternatively which is used to walk, this will provide stability, flexibility and mobility to travel on irregular surfaces. With these attributes the hexapod robots can be used to explore irregular surfaces, inhospitable places, or places which are difficult for humans to access. This paper involves the development of hexapod robot with digital image processing implemented on Raspberry Pi, to study in the areas of robotic systems with legged locomotion and robotic vision. This paper is an integration of a robotic system and an embedded system of digital image processing, programmed in high level language using Python. It is equipped with a camera to capture real time video and uses a distance sensor that allow the robot to detect obstacles. The Robot is Self-Stabilizing and can detect corners. The robot has 3 degrees of freedom in each six legs thus making a 18 DOF robotic movement. The use of multiple degrees of freedom at the joints of the legs allows the legged robots to change their movement direction without slippage. Additionally, it is possible to change the height from the ground, introducing a damping and a decoupling between the terrain irregularities and the body of the robot servo motors. Keywords: Hexapod, Raspberry Pi, Computer vision, Object detection, Yolo, Servo Motor, OpevCV.

Circular external fixators using hexapod struts are a valuable tool in the treatment of complex, multiplanar limb deformities.

Circular external fixators using hexapod struts are a valuable tool in the treatment of complex, multiplanar limb deformities.

A simulation model contributes to the development of both algorithms based on navigation sensors and their application in real nonlinear mechatronic systems. The Szabad(ka)-II hexapod walker robot is equipped with an inertial measurement unit (IMU), and this paper presents a novel calibration procedure of its simulation model. Various sinusoidal calibration movements were performed on both the model and the robot, and the raw IMU measurements were recorded simultaneously with motor electrical parameters and joint movement variables. The simulation model includes the model of IMU sensors, where the location, misalignments, and scaling parameters are also incorporated in the tuning procedure. Thus, this simulation environment enabled the calibration procedure to be performed based on the measurement data. The efficient optimization of both the unknown and estimated parameters of the robot model along with the IMU sensor model resulted in a simulation output that fits the measurement results satisfactorily. The nominal and remaining errors were analyzed both statistically and in the spectral domain. Due to the proposed method, the simulation error of the accelerometer and gyroscope measurements were decreased by 35%. The necessity of calibrating the sensor model was justified via the application of an extended Kalman filter (EKF) for the attitude estimation.