Spread enhancement for firefly algorithm with application to control mechanism of exoskeleton system

Firefly algorithm (FA) is a swarm intelligence based algorithm for global optimization and has widely been used in solving problems in many areas. The FA is good at exploring the search space and locating the global optimum, but it always gets trapped at local optimum especially in case of high dimensional problems. In order to overcome such drawbacks of FA, this paper proposes a modified variant of FA, referred to as spread enhancement strategy for firefly algorithm (SE-FA), by devising a nonlinear adaptive spread mechanism for the control parameters of the algorithm. The performance of the proposed algorithm is compared with the original FA and one variant of FA on six benchmark functions. Experimental and statistical results of the approach show better solutions in terms of reliability and convergence speed than the original FA especially in the case of high-dimensional problems. The algorithms are further tested with control of dynamic systems. The systems considered comprise assistive exoskeletons mechanism for upper and lower extremities. The performance results are evaluated in comparison to the original firefly and invasive weed algorithms. It is demonstrated that the proposed approaches are superior over the individual algorithms in terms of efficiency, convergence speed and quality of the optimal solution achieved

Tracking human upper-limb movements with sliding mode control type-II fuzzy logic

© 2016 IEEE. A knowledge of human upper-limb structure and its mechanical functions are important for developing an exoskeleton. The Sliding Mode Control with Fuzzy Type-II is proposed to control the movements of the human extremity joints. The Lagrange method is used to model the dynamics system of human upper-limb. The findings demonstrate the effectiveness of the proposed controller in tracking the desired motion and it is also able to eliminate the chattering problem as well as deal with uncertainties

Upper-limb exoskeleton for human muscle fatigue

Human muscle fatigue is identified as one of the causes to musculuskeletal disorder (MSD). The objective of this paper is to investigate the effect of an exoskeleton in dealing with muscle fatigue in a virtual environment. The focus of this work is, for the exoskeleton to provide support as needed by human joint. A (Proportional, Integration and Derivative) controller is used for both human and exoskeleton. Simmechanics and Simulink are used to evaluate the performance of the exoskeleton. Experiments show that human is able to maintain doing the job by wearing the exoskeleton

Control design of a de-weighting upper limb exoskeleton

One of the most common problems in humans is a muscle fatigue. Exoskeletons are known as one of the solution to deal with human muscle fatigue. However, several issues related to the development of exoskeletons for such a case have been identified. One of these is the control mechanism. Thus, the objective of this paper is to investigate development of a control strategy for the upper-limb exoskeleton. In this paper, a new control mechanism for an upper-limb exoskeleton is proposed. A fuzzy-based PD controller and PID are used in the proposed control mechanism, and a comparative assessment of the performance of both controllers is made. The results show that the control mechanism with fuzzy-based PD controller performs better than the PID controller in terms of trajectory tracking accuracy and control torque analysi

Maxillofacial and mandibular phenotypes in the skulls of red Sokoto and Sahel goats in Nigeria: The role of dental abnormalities

This work examined phenotypic expressions in the anatomy of the mandible and maxillofacial region of the Red Sokoto and Sahel goats in Nigeria. The infraorbital foramen was placed above premolar two (PM2) in Red Sokoto but above premolar one (PM1) in Sahel. The Red Sokoto displayed interdigital septa (ruggae) which entered into mediolateral depressions of the opposing mandible but this was less prominent in the Sahel. Dental abnormalities were more pronounced in the Red Sokoto on the maxilla and mandibular rows. The facial and mandibular tuberosities were more prominent in the Red Sokoto goat and found to be more conspicuous in this breed with dental abnormalities. There was no significant difference between Calcium and Phosphorus in the craniofacial bones of goats with dental abnormalities compared to those without dental abnormalities in both breeds and in conclusion we thus suggest that the harsh environmental conditions of arid North West may be a greater predisposing factor for the negative dental profile of the Red Sokoto breed

Growth of Pseudomonas fluorescens on Cassava Starch hydrolysate for Polyhydroxybutyrate production

The potential of local strains of microorganism (Pseudomonas fluorescens) in polyhydroxbutyrate production was investigated in this study. This was with a view to establishing the capabilities of local strains of microorganisms on utilizing renewable and locally available substrates in polyhydroxybutyrate production. This involved hydrolysis of starch extracted from freshly harvested cassava tubers using enzyme-enzyme method of hydrolysis, followed by aerobic fermentation of Pseudomonas fluorescens on a mixture of the hydrolysate and nutrient media in a fermentor in batch cultures. The reducing sugar hydrolysate served as the carbon source and diammonium sulphate as the limiting nutrient. The reaction temperature, pH and agitation rate in the fermentor were maintained at 30°C, 7.5 and 400 rpm respectively. The biomass growth was measured by cell dry weight and the polyhydroxybutyrate content measured by gas chromatography. When the fermentation process was shut down after 84 hour, the substrate consumption by the organism was 9.2 g/L to give a dry cell weight of 1.75 g/L resulting in a biomass yield on substrate (Yx/s) of 0.1902 g/g (19.02 % wt/wt). The gas chromatographic analysis gave a final polyhydroxybutyrate value of 1.254 g/L with corresponding product yield on biomass (Yp/x) of 0.7166 g g-1 [71.66% wt/wt] and product yield on substrate (Yp/s) of 0.1363 g g-1 [13.63% wt/wt]. The results show that the organism accumulated polyhydroxybutyrate in excess of 50 % of the cell dry weight by giving a final polyhydroxybutyrate yield on biomass (Yp/x) of 0.7166 g g-1 [71.66% wt/wt] which agrees with the general trend in polyhydroxybutyrate production. @ JASEMJ. Appl. Sci. Environ. Manage. December, 2010, Vol. 14 (4) 61 - 6

DEVELOPMENT OF U-CHANNEL SCREW JACK FOR VEGETABLE OIL EXTRACTION

A U-channel screw jack for extracting vegetable oil was developed through design (with Solid works–Computer Aided Design (CAD)) and fabrication processes. A factorial experiment in a Randomized Complete Block Design (RCBD) was used to investigate the effect of heating temperature (50, 60 and 70°C) and heating time (5 and 10 min) on the performance of the machine in terms of oil yield, extraction efficiency and extraction loss with groundnut as the feedstock. Results of the machine design for some of the machine components gave the following values: U-channel structural frame made of mild steel (80 x 160 x 650 mm), compression cap (70 mm) and heater band(3.5kW). Also, the performance evaluation of the machine showed that increase in heating temperature (50 to 70°C) and heating time (5 to 10 min) did not cause the oil yield, extraction efficiency and extraction loss to increase beyond 30%, 48% and 15% respectively. Generally, decrease in oil yield, extraction efficiency and extraction loss occurred at the heating temperature of 70 oC irrespective of the heating time. For future works, other machine and feedstock factors should be incorporated into the performance evaluation process. Also, automation of the machine is recommended.   http://dx.doi.org/10.4314/njt.v36i3.4

Response of maize (Zea mays L.) to combined application of organic and inorganic (soil and foliar applied) fertilizers

A field trial was carried out in the 2013 cropping season at the Teaching and Research Farm of Kwara State University, Malete, Nigeria (08° 42” 48.5N and 004° 26 17.9” E ) to assess the response of early maturing maize variety (TZEE-Y) when using organic poultry manure (pm) alone or in combination with inorganic (NPK) and foliar fertilizer (ff) (boost xtra). The treatments were: pm 5.0 t ha-1 + ff, pm 2.5 t ha-1 + NPK 30 kg N + ff, NPK 60 kg N + ff, pm 5.0 t ha-1 + NPK 60 kg N, pm 10.0 t ha-1 + 60 kg N, NPK 120 kg N/ha, pm 10.0 t ha-1 and control. The treatments were arranged in a randomized complete block design and replicated three times. Applications of poultry manure at 10.0t ha-1 produced the highest plant height (119.57 cm2), leaf area (362.10 cm2) and cob length (17.47 cm2). However, significantly, was at par with integrated application of poultry manure at 2.5 t ha-1 mixed with NPK 30 kgN ha-1 and foliar fertilizers. As compared to other treatments, significantly shorter days (38) to 50% flowering was obtained where 2.5 t ha-1 poultry manure was combined with NPK 30 kgN/ha and foliar fertilizer. The highest grain yield (3.206 t ha-1) was obtained when pm was applied alone at 10.0 t ha-1. This was also similar to the combined application of pm at 2.5t ha-1 mixed with NPK 30 kgN ha-1 and foliar fertilizer. The results of the study indicated that combined application of pm, NPK and ff enhanced the growth and yield of maize. This integrated application will be a good soil management practice for tropical soils. Combination of pm at 2.5 t ha-1 with NPK 30 kgN ha-1 and foliar fertilizer (boost xtra) is therefore recommended for early maturing maize production in the study area.Key words: Poultry manure, foliar fertilizer, mixing, NPK fertilizer, application rate

Invasive weed optimization algorithm optimized fuzzy logic scaling parameters in controlling a lower limb exoskeleton

© 2016 IEEE. This paper describes a new modified versions of invasive weed optimization algorithm with exponential seeds-spread factor. The modified invasive weed optimization algorithm (MIWO) is employed to optimize the fuzzy input-output scaling factors of lower limb exoskeleton. A fuzzy logic control (FLC) system with the (MIWO) are evolved for reference tracking control. The exoskeleton is developed to enhance and upgrade the lower limb capability and augment the torque of knee and hip of elderly people during the walking cycle. Invasive weed optimization is a bio-inspired search algorithm that mimics how weeds colonize a certain area in nature. The algorithm is modified by applying local knowledge during distribution of seeds that depends on their cost function value in each generation to narrow the accuracy and improve the local search ability. The obtained results from the modified invasive weed optimization algorithm are compared with heuristic gain values to improve the performance of the exoskeleton system. The Visual Nastran 4D software is used to develop a simulation model of the humanoid and an exoskeleton for testing and verification of the developed control mechanism. Simulation results demonstrating the performance of the adopted approach are presented and discussed

Tracking human upper-limb movements with sliding mode control type-II fuzzy logic

© 2016 IEEE. A knowledge of human upper-limb structure and its mechanical functions are important for developing an exoskeleton. The Sliding Mode Control with Fuzzy Type-II is proposed to control the movements of the human extremity joints. The Lagrange method is used to model the dynamics system of human upper-limb. The findings demonstrate the effectiveness of the proposed controller in tracking the desired motion and it is also able to eliminate the chattering problem as well as deal with uncertainties