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A proposed design and construction for a new apparatus used in measuring the solid density of masses from 1 kg up to 10 kg in the National Institute for Standards (NIS) at Egypt are presented. The apparatus operates manually and automatically for measuring the density of masses of class E using the hydrostatic weighing principle (Archimedes) according to used international standard. The principle of operation of the Hydrostatic Weighing Apparatus (HWA-NIS) depends mainly on measure the masses of the standard and the under test objects both in air and in liquid. The HWA-NIS measures the solid density with uncertainty of ±0.8 kg.m-3at coverage factor k = 2.The HWA-NIS has been used for measuring different nominal masses to validate its performance along the measuring range. The obtained results compared with the standard values. The comparison showed a good agreement between the HWA-NIS outputs and the standard values.

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Purpose This paper aims to design and control of a novel compact transportation system called the “wearable vehicle”. The wearable vehicle allows for traversing all types of terrains while transporting one's luggage in a comfortable and efficient manner. Design/methodology/approach The proposed design consists of a lower limb exoskeleton carrying two motorized wheels and two free wheels installed alongside its feet. This paper presents a detailed description of the system with its preliminary design and finite element analysis. Moreover, the system has been optimally designed to decrease wearable vehicle’s total weight, consequently leading to a reduction in motor size. Finally, two controllers have been designed to achieve stable operation of the wearable vehicle while walking. A PD controller with gravity compensation has been designed to ensure that the wearable vehicle tracks human motion, while a PID controller has been designed to ensure that the zero moment point is close to the center of the system’s support polygon. Findings Experimental tests were carried out to check the wearable vehicle concept. The obtained results prove the feasibility of the proposed wearable vehicle from the design, dynamics and control viewpoints. Practical implications This proposed wearable vehicle’s purpose is for traveling faster with less effort than normal walking. When a human comes across a flat open ground, the wearable vehicle can be used as a vehicle. However, when a human enters crowded traffic, an unstructured area or other obstacles like stairs, the vehicle can be switched into walking mode. Originality/value The wearable vehicle has seven DOFs exoskeletons, two motorized wheels, two free wheels and a foldable seat. It is used as a vehicle via its motorized and free wheels to travel fast with minimal effort. In addition, the human can switch easily into walking mode, if there is unstructured terrain to be traversed. Furthermore, an illustration of system's mechanisms and main feature parameters are presented to become acquainted with the ultimate benefits of the new system.

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