Parveen Kalra

On the solution of multimodal robot inverse kinematic functions using real-coded genetic algorithms

The inverse kinematics solution of a robotic manipulator involves transcendental equations having multiple solutions. Multiplicity resolution can be achieved by incorporating performance criterion, like total joint displacement, in the solution scheme. A real-coded genetic algorithm is used in which the fitness value of the feasible solutions, satisfying the robot kinematic equations, is taken as the total joint displacement. The fitness value of the infeasible solutions is taken as the violation of the robot kinematic equations. A multimodal robot inverse kinematics function is formed from the robot kinematic equations. A niching strategy is used to obtain simultaneously the optimal solutions of this multimodal robot inverse kinematics function. These optimal solutions provide the feasible solutions satisfying the robot kinematic equations. The fitness values associated with these feasible multiple solutions provide a means for multiplicity resolution. The approach is used to obtain the inverse kinematics solution of an articulated robotic manipulator.

On the comparison of niching strategies for finding solution of multimodal robot inverse kinematics functions

Two niching strategies for the tournament selection, along with the simulated binary crossover operator and a parameter-based mutation operator are used to solve the inverse kinematics problem of a robotic manipulator. The niching strategies are compared on the basis of their ability to evaluate the multiple inverse kinematics solutions and maintain an acceptable distribution of individuals around these solutions. The approach requires the use of robot kinematics equations and the limits of joint angles only. It does not require the use of geometric heuristics as suggested by earlier researchers. The proposed approach provides the correct number of inverse kinematics solutions even when some of them may be unachievable due to the limits of the joint angles. In other approaches, all the inverse kinematics solutions are calculated and the unachievable ones are discarded. The total joint displacements associated with the multiple inverse kinematics solutions provide a means for multiplicity resolution.

EDA wavelet features as Social Anxiety Disorder (SAD) estimator in adolescent females

Social Anxiety Disorder(SAD) effects individuals social behaviour and results in excessive self-consciousness, negative judgmental thoughts and uncontrollable fear. It is visible not only in behavior but also pattern of physiological signals (such as electrodermal activity) of individuals as it is associated with autonomic nervous system (ANS). Previous studies have used various features of Electrodermal Activity (EDA) such as Mean SCR, Min SCR, Range, Slope and Max SCL etc to distinguish between groups of anxious and control group subject during rest and anxious task/situations. This research explores the use of EDA wavelet features to estimate the social anxiety disorder of female subjects via Multi Layer Perceptron (MLP). In this study joint time-frequency domain features of EDA signal via wavelet analysis were extracted. The Backward regression model with p<;0.05 was used in this study for feature selection. The machine learning algorithm developed in this research was able to classify the SAD with accuracy of 82.3% during training, 85.7% during testing and 80% in holdout cases.

Mental Fatigue Quantification by Physiological and Neurophysiological Techniques: An Overview

Mental fatigue needs to be an essential part of industrial engineering and ergonomics. Risk assessment techniques like OCRA, REBA, etc., digital human modeling like DELMIA, RAMSIS, etc. and work station design in industry, etc., all should incorporate mental fatigue as a basic constituent. This is possible only if quantitative value of the mental fatigue is available. This is a major challenge to researchers and a focused effort towards this end is underway. Procedures of quantification of mental fatigue based on physiological and neurophysiological techniques right from their inception to date have been discussed in this paper. The usage of weighted mental fatigue indices so developed for mental and physical work also has been discussed.

Physiological Effects of Backpack Packing, Wearing and Carrying on School Going Children

Thirty male school children from primary school, aged 12 years, were selected to carry backpacks of 10% body weight where 0% body weight was used as a baseline. Heart rate and blood pressure tests were conducted on the subjects. Subjects had walked on a treadmill for 20 min at each load condition at 1.1 m/s. This was done in both cases when subjects followed the normal pattern of packing and wearing and when they followed the American Occupational Therapy Association (AOTA) recommendations. Heart rate was recorded before, during and 5 min after walking on treadmill whereas blood pressures were measured before and immediately after trial, and at 3 and 5 min after every trial. The results showed a significant difference in heart rate, blood pressure and its recovery for 10% body weight load conditions before and after recommendations. The packing, carrying, wearing of backpack should be done as per the AOTA guidelines.

Audio-video emotional response mapping based upon Electrodermal Activity

Abstract In this paper, a machine learning algorithm is proposed for emotional pattern recognition during audio-visual stimuli (music videos) using Electrodermal Activity (EDA). For emotion prediction apart from conventional time domain features of EDA signal, various features in different signal representation i.e. frequency and wavelet were analysed. The comparative result indicated that the wavelet features subset outperformed the conventional time domain features in term of classification accuracy. For identification of optimal network configuration, various combination of optimization algorithms (i.e. backpropagation algorithms) and error function were explored. The best performance of 79% for arousal, 69.8% for valence and 71.2% for dominance were obtained for emotion recognition respectively.

Fabrication and stress analysis of ankle foot orthosis with additive manufacturing

Purpose Ankle–foot orthoses (AFOs) are assistive devices prescribed for a number of physical and neurological disorders affecting the mobility of the lower limbs. Additive manufacturing has been explored as an alternative process; however, it has proved to be inefficient cost-wise. This work aims to explore the possibilities of generating modular AFO elements, namely, calf, shank and footplate, with the localized composite reinforcement that aids in the optimization of the device in terms of functionality, aesthetics, rigidity and cost. Design/methodology/approach The conventional lower leg–foot orthosis configuration depends on thermoforming a polymer sheet around a mortar cast with a trademark firmness relying upon the trim-line with the inalienable plan restrictions. In manufacturing of AFO the expert, i.e. orthotists, guidance is used. Polypropylene and polyethylene material is used in fabrication of AFO to complete all-round reported points of interest over the ordinary outlines, yet their mechanical conduct under administration conditions cannot be effectively anticipated. Findings AFOs made of polypropylene and polyethylene material are available in the market, which are used by children of age 3-5 years. With the existing AFO design, patients are facing excessive heating and sweating problems during long-term usage. After feedback from patients and orthotists (who prescribed AFO to patients), an attempt has been made to solve the problem with a new and improved AFO design of AFO by using finite element modelling and stress analysis. Also, the results indicate that the new design is similar to the actual product design. Originality/value This work introduces the low-cost 3D printing with reinforcement approach as an alternative route for the designing and manufacturing of orthotic devices with complex shapes. It is expected that new applications add-up to increase the body of knowledge about the behaviour of such products which will mix both areas, composite theory and additive manufacturing. This study investigated the fields related to 3D scanning, 3D printing and computer-aided designing for the manufacturing of a customized AFO.

“Soft that molds the hard:” Geometric morphometry of lateral atlantoaxial joints focusing on the role of cartilage in changing the contour of bony articular surfaces

Purpose: The existing literature on lateral atlantoaxial joints is predominantly on bony facets and is unable to explain various C1-2 motions observed. Geometric morphometry of facets would help us in understanding the role of cartilages in C1-2 biomechanics/kinematics. Objective: Anthropometric measurements (bone and cartilage) of the atlantoaxial joint and to assess the role of cartilages in joint biomechanics. Materials and Methods: The authors studied 10 cadaveric atlantoaxial lateral joints with the articular cartilage in situ and after removing it, using three-dimensional laser scanner. The data were compared using geometric morphometry with emphasis on surface contours of articulating surfaces. Results: The bony inferior articular facet of atlas is concave in both sagittal and coronal plane. The bony superior articular facet of axis is convex in sagittal plane and is concave (laterally) and convex medially in the coronal plane. The bony articulating surfaces were nonconcordant. The articular cartilages of both C1 and C2 are biconvex in both planes and are thicker than the concavities of bony articulating surfaces. Conclusion: The biconvex structure of cartilage converts the surface morphology of C1-C2 bony facets from concave on concavo-convex to convex on convex. This reduces the contact point making the six degrees of freedom of motion possible and also makes the joint gyroscopic.

Ergonomic Evaluation and Customized Design of Toothbrush Handle

Toothbrush handles available in the market are classified in adult, junior and baby sizes. As per IS 3387:2004, the length of the handle for these variants is specified. However, the width and thickness of the handle is not specified. As per the standard “The width and thickness of the handle may vary according to the individual design”. The focus of the current work is to design an ergonomic toothbrush handle based on hand anthropometry. This would improve the grip of the handle (user comfort) and enhance oral hygiene. A commercially available toothbrush was taken as reference to find out the optimal parameters of toothbrush handle. Hand anthropometric data of volunteers was collected. The comfort rating of these volunteers was related to the normalized handle sizes. The resulting regression equation was used to find out the optimal handle dimensions. Contact area was measured using both commercially available toothbrush handle and the same toothbrushes with different fabricated handle sleeves. Electromyography activity was recorded for muscle fatigue. The plaque index was also obtained before and after two weeks of using customized toothbrush handle. It was observed that the customized toothbrush handle was comparatively more purposeful. Relevance to Industry. From the results of this study, tooth brush designers, researchers and manufacturers can obtain guidelines for maximising grip comfort based on the hand sizes of users. The results also shows that optimal handle diameter will result in increasing the subjective comfort rating which will further increase the user performance and will lower the risk of muscle fatigue.

Gesture Based Control of a Simulated Robot Manipulator

The number of industrial and household robots is fast increasing. A simpler human-robot interaction is preferred in household robotic applications as well as in hazardous environments. Gesture based control of robots is a step in this direction. In this work, a virtual model of a 3-DOF robotic manipulator is developed using V-Realm Builder in MATLAB and the mathematical models of forward and inverse kinematics of the manipulator are coded in MATLAB/Simulink software. Human hand gestures are captured using a smartphone with accelerometer and orientation sensors. A wireless interface is provided for transferring smartphone sensory data to a laptop running MATLAB/Simulink software. The hand gestures are used as reference signal for moving the wrist of the robot. A user interface shows the instantaneous joint angles of robot manipulator and spatial coordinates of robot wrist. This simple yet effective tool aids in learning a number of aspects of robotics and mechatronics. The animated graphical model of the manipulator provides a better understanding of forward and inverse kinematics of robot manipulator. The robot control using hand gestures generates curiosity in student about interfacing of hardware with computer. It may also stimulate new ideas in students to develop virtual learning tools.Copyright