Recursive Bayesian Initialization of Localization Based on Ranging and Dead Reckoning

The initialization of the state estimation in a localization scenario based on ranging and dead reckoning is studied. Specifically, we start with a cooperative localization setup and consider the problem of recursively arriving at a uni-modal state estimate with sufficiently low covariance such that covariance based filters can be used to estimate an agent's state subsequently. A number of simplifications/assumptions are made such that the estimation problem can be seen as that of estimating the initial agent state given a deterministic surrounding and dead reckoning. This problem is solved by means of a particle filter and it is described how continual states and covariance estimates are derived from the solution. Finally, simulations are used to illustrate the characteristics of the method and experimental data are briefly presented

Understanding the Global in Global Finance and Regulation

A simple and statistically robust method for passive clock synchronization in sensor networks is presented. The method is not limited to passive (one-way communication) synchronization, but this scenario justifies the method. The recursive nature of the method and the targeted passive setup mean that it adds a minimum of requirements on the system in which it is used. Statistical characteristics of the method are quantified and real measurements are used to illustrate the robustness and performance gain relative to a naive Kalman filter based clock synchronization. Finally, C++ code that implements the suggested clock synchronization method, is provided in this article.QC 20140423</p

Businesses, buddies and babies: social ties and fertility at work

We examine the influence that co-workers’ have on each other’s fertility decisions. Using linked employer employee panel data for Sweden we show that female individual fertility increases if a co-worker recently had a child. The timing of births among co-workers of the same sex, educational level and co workers who are close in age is even more influential. Consistent with models of social learning we find that the peer effect for first time mothers is similar irrespective of the birth order of the co-worker’s child, while for higher order births within-parity peer effects are strong but cross-parity peer effects are entirely absent. A causal interpretation of our estimates is strengthened by several falsification tests showing that neither unobserved common shocks at the workplace level, nor sorting of workers between workplaces are likely to explain the observed peer effect. We also provide evidence suggesting that peers not only affect timing of births but potentially also completed fertility, and that fertility peer influences spills over across multiple networks. Our results forward the understandings of how individual fertility timing decisions are made and suggest that social interactions could be an important factor behind the strong inter-temporal fluctuations in total fertility rates observed in many countries.Peer effects; social preferences; co-workers

Occupational injuries to senior farmers in Sweden

The prevailing demographic change in the western world means that the workforce is becoming older. Farmers in particular often work beyond the normal retirement age, in a challenging physical environment. For example, the agricultural sector has the most hazardous work environment in Sweden. Therefore, it is interesting to examine the following questions: Are senior farmers more frequently involved in work-related injuries? Do some injuries happen more often in the oldest age group? Which part of the body is most frequently affected in different age groups? What can be done to decrease the risk of injury in senior farmer

Sick of your colleagues' absence?

We utilize a large-scale randomized social experiment to identify how coworkers affect each other’s effort as measured by work absence. The experiment altered the work absence incentives for half of all employees living in Göteborg, Sweden. Using administrative data we are able to recover the treatment status of all workers in more than 3,000 workplaces. We first document that employees in workplaces with a high proportion treated co-workers increase their own absence levels significantly. We then examine the heterogeneity of the treatment effect in order to explore what mechanisms are underlying the peer effect. While a strong effect of having a high proportion of treated coworkers is found for the nontreated workers, no significant effects are found for the treated workers. These results suggest that pure altruistic social preferences can be ruled out as the main motivator for the behaviour of a nonnegligible proportion of the employees in our sample.Social interactions; employer emkloyee data; work absence; fairness; reciprocal preferences

Sick of Your Colleagues' Absence?

We utilize a large-scale randomized social experiment to identify how coworkers affect each other's effort as measured by work absence. The experiment altered the work absence incentives for half of all employees living in Göteborg, Sweden. Using administrative data we are able to recover the treatment status of all workers in more than 3,000 workplaces. We first document that employees in workplaces with a high proportion treated coworkers increase their own absence level significantly. We then examine the heterogeneity of the treatment effect in order to explore what mechanisms are underlying the peer effect. While a strong effect of having a high proportion of treated coworkers is found for the nontreated workers, no significant effects are found for the treated workers. These results suggest that pure altruistic social preferences can be ruled out as the main motivator for the behaviour of a nonnegligible proportion of the employees in our sample.social interactions, employer employee data, work absence, fairness, reciprocal preferences

On Traffic Situation Predictions for Automated Driving of Long Vehicle Combinations

The introduction of longer vehicle combinations for road transports than are currently allowed is an important viable option for achieving the environmental goals on transported goods in Sweden and Europe by the year 2030. This thesis addresses how driver assistance functionality for high-speed manoeuvring can be designed and realized for prospective long vehicle combinations. The main focus is the derivation and usage of traffic situation predictions in order to provide driver support functionalities with a high driver acceptance. The traffic situation predictions are of a tactical character and include a time horizon of up to 10 s. Data collection of manual and automated driving with an A-double combination was carried out in a moving-base driving simulator. The driving scenario was comprised of a relatively curvy and hilly single-lane Swedish county road (180). The driving trajectories were analysed and complemented with results from optimization. Based on observations of utilized accelerations it was proposed that the combined steering and braking should prioritize a smooth and comfortable driving experience. It was hypothesized that high driver acceptance of driver assistance functionality including automated steering and propulsion/braking, can be realized by utilizing driver models inspired by human cognition as an integrated part in the generation of traffic situation predictions. A longitudinal and lateral driver model based on optic information was proposed for lane-change manoeuvring. The driver model was implemented in a real-time framework for automated driving of an A-double combination on a multiple lane one-way road. Simulations showed that the framework gave reasonable results for maintain lane and lane change manoeuvres at constant and varying longitudinal velocities

Cooperative localization by dual foot-mounted inertial sensors and inter-agent ranging

The implementation challenges of cooperative localization by dual foot-mounted inertial sensors and inter-agent ranging are discussed and work on the subject is reviewed. System architecture and sensor fusion are identified as key challenges. A partially decentralized system architecture based on step-wise inertial navigation and step-wise dead reckoning is presented. This architecture is argued to reduce the computational cost and required communication bandwidth by around two orders of magnitude while only giving negligible information loss in comparison with a naive centralized implementation. This makes a joint global state estimation feasible for up to a platoon-sized group of agents. Furthermore, robust and low-cost sensor fusion for the considered setup, based on state space transformation and marginalization, is presented. The transformation and marginalization are used to give the necessary flexibility for presented sampling based updates for the inter-agent ranging and ranging free fusion of the two feet of an individual agent. Finally, characteristics of the suggested implementation are demonstrated with simulations and a real-time system implementation.Comment: 14 page