Whole-body control with disturbance rejection through a momentum-based observer for quadruped robots☆

This paper presents an estimator of external disturbances for legged robots, based on the system’s momentum. The estimator, along with a suitable motion planner for the trajectory of the robot’s center of mass and an optimization problem based on the modulation of ground reaction forces, devises a whole-body controller for the robot. The designed solution is tested on a quadruped robot within a dynamic simulation environment. The quadruped is stressed by external disturbances acting on stance and swing legs indifferently. The proposed approach is also evaluated through a comparison with two state-of-the-art solutions

Head Mounted Displays for lighting in Virtual Reality: Review on Measurements, Advances and Limitations

Virtual reality has made a great progress over the past recent years both in recreational and professional fields. However, several factors can affect the capability of the virtual reality from the realism point of view. Luminance and colour of the stimuli could be considered as the main parameters which participate in this challenge. On the other hand, the complex way that virtual reality software such as the Unreal game engine manipulate the virtual scene before to be sent to the Head Mounted Display, can affect the desired goal. This review tries to have a general overview reached so far on the characterisation done in head mounted displays so as to evaluate the quantity and the quality of the light reaching users’ eyes. Further, a discussion on the open issues in the field is provided as well

Towards realistic lighted virtual environments in head-mounted displays: transfer functions effects on luminance representation

Immersive virtual reality can be considered one of the most promising technologic for developing lighting design to satisfy the standard requirements and users’ satisfaction. In this process, the deep knowledge of the relation between the digital input values to the frame buffer that controls the software, and the head-mounted displays output is crucial in affecting the users' perception. This paper presents the preliminary results of a comparison between the luminance values in the Unreal Engine 4.27 and an HTC Vive Pro head-mounted display. A simple physical environment was modelled to find the relationship between the luminance values calculated by the software and those shown by the head-mounted display. The absolute luminance values and the luminance ratios were explored by varying the number of luminaires turned on and the luminous flux. In addition, the effect of the tone mapping operator on the luminance values shown by the head-mounted display was also investigated. Results highlight that: i) tone mapping does not influence luminance values obtained in the game engine, and ii) disabling tone mapping allows showing virtual scenes in the head-mounted display whose luminance values and luminance ratios are linearly correlated with those obtained in the Unreal Engine

Passive Strategies for Building Retrofitting: Performances Analysis and Incentive Policies for the Iranian Scenario

A large amount of the Iranian energy demand is related to the building sector, mainly due to its obsolescence. In this paper, a second-skin system has been implemented as a retrofit action for an office building, evaluating the effect of a tensile material as second-skin in terms of primary energy saving, carbon dioxide equivalent emissions, and simple payback period. The analysis was carried out through numerical simulations across a whole year and for four Iranian cities (Tabriz, Teheran, Yazd, and Bandar Abbas) in four different climates (cold, temperate, hot-dry, and hot-wet), and with the building aligned at either north-south or east-west. Moreover, an economic analysis was carried out suggesting different incentive policies to promote building energy refurbishment. The simulation results highlighted a favorable orientation for buildings in Iran, suggesting a guideline for new constructions. Indeed, the best results were achieved for an east-west orientation of the building (up to a primary energy saving of 13.6% and reduction of carbon dioxide equivalent emissions of 45.5 MgCO2,eq, in Yazd), with a decrease of the annual specific total (cooling and thermal) energy demand of 37.9 kWh/m2/year. The simple payback period values were also lower in the east-west orientation than the north-south one

Passive Strategies for Building Retrofitting: Performances Analysis and Incentive Policies for the Iranian Scenario

A large amount of the Iranian energy demand is related to the building sector, mainly due to its obsolescence. In this paper, a second-skin system has been implemented as a retrofit action for an office building, evaluating the effect of a tensile material as second-skin in terms of primary energy saving, carbon dioxide equivalent emissions, and simple payback period. The analysis was carried out through numerical simulations across a whole year and for four Iranian cities (Tabriz, Teheran, Yazd, and Bandar Abbas) in four different climates (cold, temperate, hot-dry, and hot-wet), and with the building aligned at either north-south or east-west. Moreover, an economic analysis was carried out suggesting different incentive policies to promote building energy refurbishment. The simulation results highlighted a favorable orientation for buildings in Iran, suggesting a guideline for new constructions. Indeed, the best results were achieved for an east-west orientation of the building (up to a primary energy saving of 13.6% and reduction of carbon dioxide equivalent emissions of 45.5 MgCO2,eq, in Yazd), with a decrease of the annual specific total (cooling and thermal) energy demand of 37.9 kWh/m2/year. The simple payback period values were also lower in the east-west orientation than the north-south one

Improving the building envelope performance through tensile material in the Iranian climates

In this paper, the energy and environmental impacts of a passive retrofit action, involving the installation, on an office building, of a second-skin system with the external layer made of a PVC-coated polyester fabric, were evaluated in terms of primary energy saving and carbon dioxide equivalent emissions. The primary energy consumption and the carbon dioxide equivalent emissions associated with the considered case studies were evaluated using the software TRNSYS, across a whole year. The study was carried out considering three Iranian cities (Tabriz, Teheran and Bandar Abbas) in three different climates (cold, temperate and hot) upon varying the orientation of the two main façades of building (north-south and east-west orientation). The simulation results highlighted good results when the building is east-west oriented, up to -12.9% for the reduction of primary energy consumption (in Teheran) and up to -42.1 MgCO2,eq (in Tabriz) for the carbon dioxide equivalent emissions