Development of stable telecontrol and teleoperation of the AutoMerlin mobile robot

Mobile robots have played a crucial role since their inception and the research in the field of mobile robotics is ever increasing day by day because they have vast applications. These robots have brought easiness and comfort to human’s life. There are different ways in which mobile robots navigate, e.g. some move autonomously while others have a human operator as their motion planner and executor. The involvement of a human operator gave rise to the idea of the development of teleoperated robots. Teleoperated robots have helped in planetary explorations, landmines clearance, and explosive materials handling in dangerous environments, e.g. they are actively involved in the radioactive material handling of the nuclear power plants. Telecontrol and teleoperation consist of a human operator, a control station, a communication medium, a slave robot, and the remote environment. Initially, a dedicated medium like a radio link was used as a communication link between the control station and the slave robot. The communication involved some delay in the data and signal transmission. The delay was constant and the control laws were modified according to the new scenario. The dedication of a specific link for the communication was costly and it could not attract many researchers. But with the advent of the Internet, the researchers started utilizing it for the development of teleoperated robots. The main advantage of the Internet is its availability and cost. But as the Internet is a shared medium, therefore, it has an inherent delay in it. This delay is random in nature. Apart from delay it also has other limitations like packet drops, duplication of data, out of order arrival of packets, etc. The design of a controller with such limitations was a challenging task. Therefore, different solutions have been proposed to develop a stable telecontrol of the mobile robot AutoMerlin. At first, the Event-based Control was implemented to limit the execution time of the input commands so that the robot remains stable even in the presence of a delay. After that fuzzy soft computing was employed to design a controller, which was immune to a network delay. It has two inputs, one input comes from the human operator and the other input comes from the sonar sensors which map the environment and calculate the distance to the obstacle and provide it to the speed controller for an appropriate output speed. An ancillary intelligence has been provided to avoid obstacles autonomously in case of connection loss between the human operator and the mobile robot. Finally, Time Domain Passivity Control has been implemented to design a bilateral controller. It is a non-model-based controller which doesn’t add any extra damping to the system and also there is no need to make any compromise on any parameter of the system. It is based on Two-port network. The controller has been designed with only one port active. Then, the work has been extended to design a bilateral controller with both ports active having a constant and stochastic delay and other network impediments using Time Delay Power Network approach. The force feedback has been rendered back to the human operator. Several experiments have been performed to test the performance and robustness of the controllers. The performance evaluation data has been plotted. Stable teleoperation has been achieved and it has been deployed to the mobile robot AutoMerlin. In the end, the Probabilistic Neuro-fuzzy and ANFIS have been used to design a leader-follower setup of multiple mobile robots. A simulation has been done to visualize the performance of the proposed algorithm and the Probabilistic Neuro-fuzzy has been implemented on the real robot.Mobile Roboter haben seit ihrer Entwicklung eine entscheidende Rolle gespielt und die Forschung im Feld mobiler Robotik nimmt andauernd zu, da diese in vielen Anwendungen eingesetzt werden. Diese Roboter haben Leichtigkeit und Komfort in das Leben des Menschen gebracht. Es gibt verschiedene Arten in denen mobile Roboter navigieren. Manche bewegen sich autonom, während andere einen menschlichen Anwender zur Planung und Ausführung ihrer Bewegungen haben. Die Beteiligung eines menschlichen Anwenders förderte die Idee der Entwicklung von teleoperierten Robotern. Teleoperierte Roboter werden bereits bei planetarischen Erkundungen, bei der Landminen Beseitigung und dem Transport von explosivem Material in gefährlichen Umgebungen eingesetzt. Zum Beispiel werden sie aktiv zur Handhabung von radioaktiven Materialien in Kernkraftwerken eingesetzt. Zur Fernsteuerung und Tele-Operation wird ein menschlicher Anwender, eine Kontrollstation, eine Kommunikationsverbindung, ein Roboter und ein entferntes Einsatzgebiet benötigt. Anfangs wurde eine Radioverbindung als eine Kommunikationsverbindung zwischen dem Sender und dem Roboter verwendet. Die Kommunikation beinhaltete eine Verzögerung bei der Daten- und Signalübertragung. Die Verzögerung war konstant, und die Regelungsgesetze wurden entsprechend dem neuen Szenario modifiziert. Die Entwicklung einer spezifischen Kommunikationsverbindung war kostspielig und konnte nicht viele Forscher überzeugen. Mit dem Aufkommen des Internets begannen Forscher dieses in die Entwicklung von teleoperierten Robotern einzubinden. Der Hauptvorteil des Internets ist seine Verfügbarkeit und die geringen Kosten. Da das Internet ein geteiltes Kommunikationsmedium ist, hat es eine inhärente Verzögerung. Neben der Verzögerung können auch Informationspakete verloren gehen, doppelt ankommen oder zu einer anderen Zeit eingehen. Deshalb werden verschiedene Lösungen vorgeschlagen, um eine stabile Fernsteuerung vom mobilen Roboter AutoMerlin zu entwickeln. Zuerst wurde eine Ereignis basierte Regelung eingeführt, um die Ausführungszeit der Eingangsbefehle zu begrenzenso dass der Roboter, trotz auftretender Verzögerungen in der Signalübertragung, stabil bleibt. Hiernach wurde Fuzzy-Logik verwendet um einen Regler zu entwerfen, welcher unabhängig von Netzverzögerungen funktioniert. Dieser hat zwei Eingänge. Ein ingangssignal kommt von dem menschlichen Anwender, während der andere Eingang von den Sonarsensoren kommt, die die Umgebung kartografisch darstellen, die Entfernung zum Hindernis berechnen und diese Information dem Geschwindigkeitsregler zur Verfügung stellen der eine angemessene Ausgangsgeschwindigkeit bestimmt. Um Hindernissen autonom im Falle von Verbindungsverlust zwischen dem menschlichen Anwender und dem mobilen Roboter auszuweichen, wurde eine untergeordnete Intelligenz implementiert. Zuletzt wurde Time Domain Passivity Control eingeführt, um einen bilateralen Regler zu entwerfen. Dabei handelt es sich um einen Nicht-modellbasierten Regler, der dem System keine zusätzliche Dämpfung zufügt. Ausserdem müssen keine Kompromisse bei den Parametern des Systems eingegangen werden. Dies basiert auf einem zwei-Kanal Netzwerk. Der Regler wurde mit nur einem aktiven Kanal entwickelt. Unter Verwendung des Time Delay Power Network Ansatzes wurde die Arbeit um einen bilateralen Regler mit zwei aktiven Kanälen, einer konstanten und stochastischen Verzögerung und anderen Netzwerk Beeinträchtigungen erweitert. Das Force Feedback wurde an den menschlichen Anwender zurückgeführt. Verschiedene Versuche zur Uberprüfung der Leistung und der Stabilität des Reglers wurden durchgeführt und dargestellt. Stabile Teleoperation wurde erreicht und an dem mobilen Roboter AutoMerlin eingesetzt. Zuletzt wurden der probabilistische Neuro-fuzzy und ANFIS eingesetzt, um ein leader-follower Setup von multiplen mobilen Robotern aufzubauen. Die Leistung des vorgestellten Algorithmus wurde in einer Simulation dargestellt. Der probabilistische Neuro-fuzzy wurde auf dem realen Roboter implementiert

Thermal Conductivity and Non-Newtonian Behavior of Complex Plasma Liquids

Understanding of thermophysical properties of complex liquids under various conditions is of practical interest in the field of science and technology. Thermal conductivity of nonideal complex (dusty) plasmas (NICDPs) is investigated by using homogeneous nonequilibrium molecular dynamics (HNEMD) simulation method. New investigations have shown, for the first time, that Yukawa dusty plasma liquids (YDPLs) exhibit a non-Newtonian behavior expressed with the increase of plasma conductivity with increasing external force field strength Fext. The observations for lattice correlation functions Ψ (t) show, that our YDPL system remains in strongly coupled regime for a complete range of plasma states of (Γ, κ), where (Γ) Coulomb coupling and (κ) Debye screening length. It is demonstrated, that the present NICDP system follows a simple scaling law of thermal conductivity. It has been shown, that our new simulations extend the range of Fext used in the earlier studies in order to find out the size of the linear ranges. It has been shown that obtained results at near equilibrium (Fext = 0.005) are in satisfactory agreement with the earlier simulation results and with the presented reference set of data showed deviations within less than ±15% for most of the present data points and generally overpredicted thermal conductivity by 3–22%, depending on (Γ, κ)

Applications of Diagnostic Reference Levels of Standard Doses in Nuclear Medicine

The concepts of diagnostic reference levels (DRLs) and achievable doses (ADs) have been developed to optimize the imaging procedures, both diagnostic and interventional, involving ionizing radiation. These are not dose limits but are used to evaluate the performance of clinical exams. Most countries have developed their own DRLs and ADs depending on the medical practice of administrating radioactivity to patients. In this project, the intent was to establish these quantities in nuclear medicine according to the prevailing practices of our country. Data were collected for all gamma ray imaging procedures both for adults as well as for children. An attempt was made to include as many hospitals and patients as possible to get good statistics. The survey data showed the range of minimum and maximum administered activities is quite large for many commonly performed nuclear medicine studies. DRLs and ADs are selected at the 75th and 50th percentiles of the survey data to represent state-of-the-practice. DRLs are not regulatory limits or to establish legal standards of care. In addition, DRLs are not applicable to the doses for individual patients. It is essential to ensure that the appropriate clinical information is available in the image throughout the optimization process

Non-Newtonian Dynamics with Heat Transport in Complex Systems

Transport properties of complex system under various conditions are of practical interest in the field of science and technology. Homogenous nonequilibrium molecular dynamics (HNEMD) simulations have been employed to calculate the thermal conductivity (λ) of three-dimensional (3D) strongly coupled complex nonideal plasmas (SCCNPs) over a suitable range of plasma parameters (Γ, κ). New investigations show that the λ depending on plasma parameters and minimum value of λ exists at nearly same plasma states. In the present case, the non-Newtonian behavior is checked with different system sizes and it is found that the λ behavior is well matched with earlier numerical work. It is demonstrated that the present outcomes are more consistent than those obtained earlier known simulations. It is revealed that our outcomes can be acceptable for a low range of force field in order to find out the size of linear ranges, and it explains the nature of nonlinearity of SCCNPs. It has been shown that the measured outcomes at steady states of external field of F* (=0.005) are in acceptable agreement with previous numerical outcomes, and it showed that the deviations are within less than 12% for most of the data and depend on plasma states

Cultural impact on trust-building process between Norwegian and Pakistani importers/exporters (traders)

Masteroppgave i bedriftsøkonomi - Universitetet i Nordland, 201

Price Forecasting Model for Perishable Commodities: A Case of Tomatoes in Punjab, Pakistan.

This study focused on developing forecasting model for perishable commodities and tomato is taken as a case to study. The model is developed on in-depth analysis of market dynamics and structure. An estimable theoretically founded model is the major output of this study which is based on true structure of the market. Complete model is comprised of inverted demand equation, Plantation and yield equations and the role of price expectations. The study reveals the fact that the farmers’ production decisions are affected by the expected profitability which is based on the expected output prices. However, due to the involvement of certain intermediaries the farmers couldn’t get the proper prices of its output whereas the domestic production meets 31.5% to its total demand only and the deficit is imported from other provinces of the country and from India. Low per acre yield and inefficient management practices, non-availability of hybrid seed, weather conditions and less profit margins and declining area of production causes the production to fall short of its potential maximum. Moreover, the increased reliance on imports and the increased demand due to increase in population causes the domestic prices to becomes more volatile. The majority of the small farmers sell their product through commission agents and wholesaler that cause imperfections in the market. Tomatoes value chain have certain problems like there exists a disparity between the small and large farmers in cost of production, yield and profitability. The model may forecast the prices on monthly or weekly basis depending upon the data availability

Policy Reforms & Analysis of Wheat Procurement System in Punjab, Pakistan.

The current policy of minimum price prevailing in the country should be abandoned as although this policy encourages the farmers to produce greater amounts of wheat but it is unfavorable for the government. Instead of minimum price policy, input costs need to be reduced to compete in the international markets as higher domestic prices leave a country internationally uncompetitive and increase the costs to the economy. The objective of this study was to find suitable price policy reforms. Extensive analysis revealed that higher cost of production is the main reason for higher domestic prices. Therefore, the study proposes that controlling and reducing input costs will benefit the farmers as well as the economy. Subsidies on inputs, especially fertilizers, should be given by the government as this will reduce the cost of production significantly. Moreover, reduced input cost for wheat will be the appropriate policy intervention which will lead to achieve international competitiveness. Thus, the policy recommendation on the basis of the analysis carried out in the previous sections is that subsidy should be given on inputs of wheat, especially fertilizers, to reduce the cost of production, as reduction in the production cost will proportionately reduce the support price

Policy Reforms & Analysis of Wheat Procurement System in Punjab, Pakistan.

The current policy of minimum price prevailing in the country should be abandoned as although this policy encourages the farmers to produce greater amounts of wheat but it is unfavorable for the government. Instead of minimum price policy, input costs need to be reduced to compete in the international markets as higher domestic prices leave a country internationally uncompetitive and increase the costs to the economy. The objective of this study was to find suitable price policy reforms. Extensive analysis revealed that higher cost of production is the main reason for higher domestic prices. Therefore, the study proposes that controlling and reducing input costs will benefit the farmers as well as the economy. Subsidies on inputs, especially fertilizers, should be given by the government as this will reduce the cost of production significantly. Moreover, reduced input cost for wheat will be the appropriate policy intervention which will lead to achieve international competitiveness. Thus, the policy recommendation on the basis of the analysis carried out in the previous sections is that subsidy should be given on inputs of wheat, especially fertilizers, to reduce the cost of production, as reduction in the production cost will proportionately reduce the support price