Non-parametric regression for robot learning on manifolds

Many of the tools available for robot learning were designed for Euclidean data. However, many applications in robotics involve manifold-valued data. A common example is orientation; this can be represented as a 3-by-3 rotation matrix or a quaternion, the spaces of which are non-Euclidean manifolds. In robot learning, manifold-valued data are often handled by relating the manifold to a suitable Euclidean space, either by embedding the manifold or by projecting the data onto one or several tangent spaces. These approaches can result in poor predictive accuracy, and convoluted algorithms. In this paper, we propose an "intrinsic" approach to regression that works directly within the manifold. It involves taking a suitable probability distribution on the manifold, letting its parameter be a function of a predictor variable, such as time, then estimating that function non-parametrically via a "local likelihood" method that incorporates a kernel. We name the method kernelised likelihood estimation. The approach is conceptually simple, and generally applicable to different manifolds. We implement it with three different types of manifold-valued data that commonly appear in robotics applications. The results of these experiments show better predictive accuracy than projection-based algorithms.Comment: 17 pages, 15 figure

The Role of Roles: Physical Cooperation between Humans and Robots

Since the strict separation of working spaces of humans and robots has experienced a softening due to recent robotics research achievements, close interaction of humans and robots comes rapidly into reach. In this context, physical human–robot interaction raises a number of questions regarding a desired intuitive robot behavior. The continuous bilateral information and energy exchange requires an appropriate continuous robot feedback. Investigating a cooperative manipulation task, the desired behavior is a combination of an urge to fulfill the task, a smooth instant reactive behavior to human force inputs and an assignment of the task effort to the cooperating agents. In this paper, a formal analysis of human–robot cooperative load transport is presented. Three different possibilities for the assignment of task effort are proposed. Two proposed dynamic role exchange mechanisms adjust the robot’s urge to complete the task based on the human feedback. For comparison, a static role allocation strategy not relying on the human agreement feedback is investigated as well. All three role allocation mechanisms are evaluated in a user study that involves large-scale kinesthetic interaction and full-body human motion. Results show tradeoffs between subjective and objective performance measures stating a clear objective advantage of the proposed dynamic role allocation scheme

The effects of boron supplementation of layer diets varying in calcium and phosphorus concentrations on performance, egg quality, bone strength and mineral constituents of serum, bone and faeces

WOS: 000346566600014PubMed ID: 253300401. A 2x3 factorial arrangement of treatments was used to investigate the effects of dietary calcium (Ca), phosphorus (P), and supplemental boron (B) (0, 75, and 150mg/kg) on the performance, egg quality, bone strength, and mineral constituents in bone, serum and faeces. 2. A reduction by 18% in the dietary Ca-P concentration from the recommended levels for the hen strain reduced (P0.01) faecal excretion of ash, Ca and P concentrations, and shear force with stress of the tibia in association with decreased feed intake, whereas improved albumen height and Haugh unit values in the egg. 3. Supplemental B significantly decreased the feed consumption, egg weight and final body weight in hens, as well as the albumen height, but had no effect on either the biomechanical characteristics of bones or the mineral profile of the bones and serum. However, there was a significant increase in the egg production rate and a reduction in the damaged and shell-less egg ratio, and in the feed conversion rate in hens fed adequate Ca-P with 150mg/kgB compared to those of the unsupplemented controls. 4. The amount of B that accumulated in the bones and serum was correlated with the amount of B consumed. B increased the faecal excretion of ash, Ca and B. In general, dietary variables had no effect on mineral composition of serum and tibia. 5. The magnitude of the response to dietary B was much more pronounced in hens fed a diet deficient in Ca-P with 75mg/kgB; these hens exhibited a production performance and an egg quality comparable to those given adequate Ca-P with no added B. 6. The data presented in this study describing the measured bone properties did not corroborate the hypothesis that B is a trace element playing an important role in mineral metabolism and bone strength through an interaction with Ca, P and Mg

Effect of a herbal essential oil mixture on growth and internal organ weight of broilers from young and old breeder flocks

WOS: 000240180400009The aim of the present study was to examine the effects of a herbal essential oil mixture on the performance of broilers produced by a young (30 wk) or an old breeder (80 wk) flock. One thousand and eight unsexed day-old broiler chicks (Ross-308) originating from the two breeder flocks were randomly allocated to three treatment groups of 336 birds each. Dietary treatments were: a control and two diets containing 24 mg/kg or 48 mg/kg of an essential oil mixture. There were no significant effects of dietary treatment on body weight of the broilers at 21 and 42 days. The effect of the age of the parents did not have a significant effect on body weight of the broilers at 21 and 42 days of age. Up to 21 days the feed intake of broilers from young breeders was reduced significantly as a result of the inclusion of the essential oil mixture in their diets, and a significant improvement in feed conversion ratio was recorded in these birds. Difference in regression coefficients for feed intake and feed conversion ratio between broilers from young and old breeder flocks was significant. Carcass yield and some internal organ weights such as the liver, pancreas, proventriculus, gizzard and small intestine were not affected by the addition of the essential oil mixture to the diet. Inclusion of essential oil mixture to the diet decreased mortality significantly at 21 days

Comparing the profitability of organic and conventional broiler production

Recently, organic broiler chicken production has received more attention worldwide. This study has carried out an economic analysis to compare the profitability of organic versus conventional growing systems per unit of broiler meat production. To achieve this goal, 400 slow-growing broiler chickens (Hubbard Red-JA) were reared in an organic production system, and the same number of fast-growing birds (Ross-308) in a conventional system. The profitability was deduced with an economic analysis that compared total costs and net income. Results showed that organic broiler meat can cost from 70% to 86% more with respect to variable and fixed costs when compared with conventional production. The main reasons for the higher cost of organic broiler meat were feed, labor, certification, and outdoor area maintenance. The proportion of fixed costs in total costs was 1.54% in the conventional system and 7.48% in the organic system. The net income per kg of chicken meat in the organic system was € 0.75, which is 180% higher than chicken meat grown in a conventional system (€ 0.27); however, the price of organic broiler meat sold in the present study was twice as high as that obtained for conventional broilers. In conclusion, organic broiler meat production was more profitable than conventional rearing

Effect of an herbal essential oil mixture on growth, laying traits, and egg hatching characteristics of broiler breeders

WOS: 000271292000018PubMed ID: 19834088The effects of supplementing a basal diet with 2 levels of an essential oil mixture and an antibiotic on the growth, laying traits, and egg hatching characteristics of broiler breeders were examined in this study. Nine hundred sixty female and 128 male breeders at an age of 1 d old were randomly allocated to 16 replicates (i.e., 4 replicates of 4 dietary treatments) in a floor pen trial. Two levels of an essential oil mixture (EOM; i.e., 24 and 48 mg of EOM/kg of diet) and an antibiotic (i.e., 10 mg of avilamycin/kg of diet) were added to the basal starter, grower, and laying diets from 0 to 45 wk of age. Daily feed allocations were adjusted to produce a target BW and egg production rate of the breeders throughout the experimental period. The BW of the males and females were determined at 12, 21, and 45 wk of age. Livability during the growing and laying period was not affected by the dietary treatments. The fertility and hatchability of total eggs set were positively affected by the supplementation of the EOM in the diet (P < 0.01). The hen-day egg production, hatching egg weight, settable egg ratio, hatching of fertile eggs, extra large egg rate, and proportion of chick weight to egg weight were not affected significantly. The higher level of EOM (48 mg/kg) added to the diet led to the hatching of the heaviest chickens; the lower level of EOM (24 mg/kg) and antibiotic treatments led to the hatching of the intermediate weight chickens, followed by the control treatment (P < 0.01). Hens given the lower level of EOM in their diets produced a higher number of settable eggs and chicks as compared with those of other treatments, whereas hens fed the control diet yielded the lowest total settable eggs and chicks throughout the experimental laying period (P < 0.05). The results of this study showed that supplementing diets with EOM improved fertility, the hatchability of total eggs set, total settable eggs, total chicks, and the chick weight of broiler breeders

Effects of administering an essential oil mixture and an organic acid blend separately and combined to diets on broiler performance

This study compares the performance-enhancing effects of adding an antibiotic growth promoter (AGP), a commercial organic acid blend (OAB), a commercial, herbal, essential oil mixture (EOM) and an OAB - EOM combination to feeding regimens of broiler chicks. The corn and soybean-based basal diet was supplemented with three doses of one of the following additives: AGP (Avilamycin, 10 mg/kg diet), OAB (0.9, 1.8, 2.7 g/kg diet, respectively), EOM (12, 24, 36 mg/kg diet, respectively) and OAB - EOM combination. Diets were fed as mash to 3,300 one-day-old broiler chicks (Ross-308) that were randomly assigned to 11 groups, each with six identical subgroups. Birds were studied until they were 42 days old