Modular and Analytical Methods for Solving Kinematics and Dynamics of Series-Parallel Hybrid Robots

While serial robots are known for their versatility in applications, larger workspace, simpler modeling and control, they have certain disadvantages like limited precision, lower stiffness and poor dynamic characteristics in general. A parallel robot can offer higher stiffness, speed, accuracy and payload capacity, at the downside of a reduced workspace and a more complex geometry that needs careful analysis and control. To bring the best of the two worlds, parallel submechanism modules can be connected in series to achieve a series-parallel hybrid robot with better dynamic characteristics and larger workspace. Such a design philosophy is being used in several robots not only at DFKI (for e.g., Mantis, Charlie, Recupera Exoskeleton, RH5 humanoid etc.) but also around the world, for e.g. Lola (TUM), Valkyrie (NASA), THOR (Virginia Tech.) etc.These robots inherit the complexity of both serial and parallel architectures. Hence, solving their kinematics and dynamics is challenging because they are subjected to additional geometric loop closure constraints. Most approaches in multi-body dynamics adopt numerical resolution of these constraints for the sake of generality but may suffer from inaccuracy and performance issues. They also do not exploit the modularity in robot design. Further, closed loop systems can have variable mobility, different assembly modes and can impose redundant constraints on the equations of motion which deteriorates the quality of many multi-body dynamics solvers. Very often only a local view to the system behavior is possible. Hence, it is interesting for geometers or kinematics researchers, to study the analytical solutions to geometric problems associated with a specific type of parallel mechanism and their importance over numerical solutions is irrefutable. Techniques such as screw theory, computational algebraic geometry, elimination and continuation methods are popular in this domain. But this domain specific knowledge is often underrepresented in the design of model based kinematics and dynamics software frameworks. The contributions of this thesis are two-fold. Firstly, a rigorous and comprehensive kinematic analysis is performed for the novel parallel mechanisms invented recently at DFKI-RIC such as RH5 ankle mechanism and Active Ankle using approaches from computational algebraic geometry and screw theory. Secondly, the general idea of a modular software framework called Hybrid Robot Dynamics (HyRoDyn) is presented which can be used to solve the geometry, kinematics and dynamics of series-parallel hybrid robotic systems with the help of a software database which stores the analytical solutions for parallel submechanism modules in a configurable and unit testable manner. HyRoDyn approach is suitable for both high fidelity simulations and real-time control of complex series-parallel hybrid robots. The results from this thesis has been applied to two robotic systems namely Recupera-Reha exoskeleton and RH5 humanoid. The aim of this software tool is to assist both designers and control engineers in developing complex robotic systems of the future. Efficient kinematic and dynamic modeling can lead to more compliant behavior, better whole body control, walking and manipulating capabilities etc. which are highly desired in the present day and future robotic applications

Effect on air quality and treatment of solid waste generated during processing of iron ores for steel making

In this investigation an estimate of SPM generated on simulated industrial crushing without proper dust collection system is carried out at laboratory. The SPM level was found to be 1496.09 ug/m3 without dust collection system which is much higher then the specified limit. Thus calls for proper during processing of iron ores was treated in a wet high intensity magnetic separator (WHIMS) and flotation. It was possible to produce concentrate with Fe content of 64.9% having yield of 48.7% by WHIMS and 64.5% having yield of 47% by flotation. That can be directly used as pellet feed to DRI plants. The remaining waste material may be treated with flocculants such as starch-alum combination followed by solid/Liquid separation for safe disposal

EFFECT OF NARINGENIN ON LIPIDS, LIPOPROTEINS AND LIPID METABOLISING ENZYMES IN 7,12-DIMETHYL BENZ(A)ANTHRACENE-INDUCED MAMMARY CARCINOGENESIS IN SD RATS

Objective: Mammary carcinoma is one of the most common and prominent cause of cancer-related death in women worldwide. The role of fatty acid synthesis and altered lipid metabolism in cancer progression was well established. Cancer cells undergo enhanced de-novo lipogenesis and liver uptake. The magnitudes of bioflavonoids in lipid management against various cancers have been established. In the present study, we evaluated the efficacy of a bioflavonoid Naringenin (NGN) to re-establish the lipid metabolic alterations in 7, 12-dimethyl benz (a) anthracene (DMBA)-induced mammary carcinoma in Sprague Dawley (SD) rats.Methods: DMBA-induced mammary carcinoma was developed using air pouch technique (20 mg in 0.5 ml olive oil) following a 118 d experimental protocol. NGN (40, 80 mg/kg b. w.; i. p.) was given for 28 d after promotional stage (90 d) of carcinoma bearing animals. The changes in body weight (b. w.), lipids, lipoproteins and lipid metabolising enzymes (LME) level were estimated and correlated with anticancer potentials of NGN.Results: The results indicated a dose dependant significant (p<0.05) restorative effect of NGN on body weight of cancer-bearing animals. The changes in lipid level in plasma and liver tissue were re-established after treatment. Lipoproteins and LME were also changed in cancer-bearing animals with that of NGN treatment significantly (p<0.01).Conclusion: NGN potentially reverted the changes in body weight, lipid profile, LME that config. its anticancer potential against mammary carcinogenesis.Â

A Defected Ground Structure Based Compact Circular Patch Antenna Design for mm Wave Application

This paper presents a novel defected ground structure-based slotted circular patch antenna for mm-Wave application. A circular patch antenna with a compact size of 10 mm×8 mm×0.75 mm is fabricated in the lab. The designed antenna has a 2 GHz impedance bandwidth that covers the frequency range of 42GHz to 44GHz. It achieves a directional radiation pattern for millimeter-wave applications and has a maximum realized gain of 6 dBi at the operating frequency of 42.65 GHz. Defected ground structure (DGS) is loaded on the bottom of the dielectric substrate, which improves the gain and reduces the surface wave propagation. The proposed antenna has achieved circular polarization which makes it suitable for the mm-Wave application

Analytic Estimation of Region of Attraction of an LQR Controller for Torque Limited Simple Pendulum

Linear-quadratic regulators (LQR) are a well known and widely used tool in control theory for both linear and nonlinear dynamics. For nonlinear problems, an LQR-based controller is usually only locally viable, thus, raising the problem of estimating the region of attraction (ROA). The need for good ROA estimations becomes especially pressing for underactuated systems, as a failure of controls might lead to unsafe and unrecoverable system states. Known approaches based on optimization or sampling, while working well, might be too slow in time critical applications and are hard to verify formally. In this work, we propose a novel approach to estimate the ROA based on the analytic solutions to linear ODEs for the torque limited simple pendulum. In simulation and physical experiments, we compared our approach to a Lyapunov-sampling baseline approach and found that our approach was faster to compute, while yielding ROA estimations of similar phase space area.Comment: 7 pages, 5 figures, 2 tables, to be published in proceedings of 61st IEEE Conference on Decision and Control (CDC