Safety Guaranteed Control for Spacecraft Inspection Mission

This paper investigates the safety guaranteed problem in spacecraft inspection missions, considering multiple position obstacles and logical attitude forbidden zones. In order to address this issue, we propose a control strategy based on control barrier functions, summarized as "safety check on kinematics" and "velocity tracking on dynamics" approach. The proposed approach employs control barrier functions to describe the obstacles and to generate safe velocities via the solution of a quadratic programming problem. Subsequently, we design a proportional-like controller based on the generated velocity, which, despite its simplicity, can ensure safety even in the presence of velocity tracking errors. The stability and safety of the system are rigorously analyzed in this paper. Furthermore, to account for model uncertainties and external disturbances, we incorporate an immersion and invariance-based disturbance observer in our design. Finally, numerical simulations are performed to demonstrate the effectiveness of the proposed control strategy.Comment: 22 pages, 9 figures, submitted to JGC

Incorporating cultural value into a service brand- Strategic branding for ALV

This thesis presents a strategic branding project of Active Life Village OY (ALV), a Finnish elderly-care service start-up. In Finland, waves of retirees, known as the post-WWII baby boomers, burst the once-solid public elderly care sector, which reveals opportunities for the private elderly-care service providers like ALV. Finnish baby boomers, as a crossroads and bridging generation (Karisto, 2007), differ from previous generations. Hence, their distinctive value requires ALV outlining tailored strate-gies to accommodate this emerging target group. This brand research attempts a new approach, Service Driven Cultural Innovation (SDCI), adapted from Cultural branding approach (Holt, 2004) in Service brand logic ((Merz et al., 2009). A literature review is presented to link the Cultural approach to service-dominant logic (Vargo & Lusch, 2004a, 2004b, 2008), which provides an initial methodology of SDCI that encourage cultural innovations through collective identity project of consumers in a co-created cultural context of the service system of a brand. The strategic branding research of ALV is then structured in according to the Design Research methodology (Blessing & Chakrabarti, 2009) to further demonstrate and validate this SDCI approach in terms of the procedures, corresponding methods and key insights gained from each stage. Firstly, a phenomenological inquiry, through identity project interview (Holt & Thompson, 2004) assisted by image probing technique, brings out Finnish boomers’ distinct cultural in-sights about their impending elderly life. Then, a co-design workshop, in the fashion of a World café, was organized to transmute these insights into service-based brand strategies in a collaborative manner. Finally, the design process and outcomes were evaluated, with data collected according to Kirkpatick model (Kirkpatick,1959) , which provides an initial validation of the SDCI approach. Overall, the results and findings of this design research suggest that ALV should propose new service system that incorporates the cultural context in which boomers, by practicing collective identity project, actively adapt to the bodily and mental changes while aging. More specifically, this service system should feed boomers’ cultural aspiration by reinventing elder life from three aspects- ‘aging in balance’, ‘relationship and home’, and ‘passion to serve’. The ALV service-branding project resulted in achievable and comprehensive service concepts, which are highly appreciated by the client and has been adopted for their future business development plan. Consequentially, SDCI approach proves to be applicable to service companies, especially small ones with limited resources like ALV. In addition, this thesis provides brand practitioners, especially service designers, instruments to elicit holistic cultural insights from a particular cultural group and translate the insights into service opportunities that co-create brand value with target consumers. Moreover, this thesis stressed the important role of service designer in the brand development and innovation, which may also suggest new career paths for service designer to follow

C2,αC^{2,\alpha} regularity of free boundaries in optimal transportation

In this paper we establish the $C^{2,\alpha}$ regularity for free boundary in the optimal transport problem in all dimensions.Comment: In this updated version, we are able to obtain the $C^{2,\alpha}$ regularity for free boundary in the optimal transport problem in all dimension

Global regularity of optimal mappings in non-convex domains

In this paper, we establish a global regularity result for the optimal transport problem with the quadratic cost, where the domains may not be convex. This result is obtained by a perturbation argument, using a recent global regularity of optimal transportation in convex domains by the authors.Comment: accepted for publication in SCIENCE CHINA Mathematic

Adaptive Reduced-Attitude Control for Spacecraft Boresight Alignment with Safety Constraints and Accuracy Requirements

This paper investigates the boresight alignment control problem under safety constraints and performance requirements, involving pointing-forbidden constraint, attitude angular velocity limitation, and pointing accuracy requirement. Meanwhile, the parameter uncertainty issue is taken into account simultaneously. To address this problem, we propose a modified composite framework integrating the Artificial Potential Field (APF) methodology and the Prescribed Performance Control (PPC) scheme. The APF scheme ensures safety, while the PPC scheme is employed to realize an accuracy-guaranteed control. A Switched Prescribed Performance Function (SPPF) is proposed to facilitate the integration, which monitors various constraints and further establishes compatibility between safety and performance concerns by leveraging a special PPC freezing mechanism. To further address the parameter uncertainty, we introduce the Immersion-and-Invariance (I\&I) adaptive control technique to derive an adaptive APF-PPC composite controller, further guaranteeing the closed-loop system's asymptotic convergence. Finally, numerical simulations are carried out to validate the effectiveness of the proposed scheme.Comment: Submitted to T-AE

Abnormal Event Detection Based on Deep Autoencoder Fusing Optical Flow

International audienceAs an important research topic in computer vision, abnormal detection has gained more and more attention. In order to detect abnormal events effectively, we propose a novel method using optical flow and deep autoencoder. In our model, optical flow of the original video sequence is calculated and visualized as optical flow image, which is then fed into a deep autoencoder. Then the deep autoencoder extract features from the training samples which are compressed to low dimension vectors. Finally, the normal and abnormal samples gather separately in the coordinate axis. In the evaluation, we show that our approach outperforms the existing methods in different scenes, in terms of accuracy