Understanding the intricacies of Venus is key in the field of planetary science and provides invaluable insights into the evolution of Earth. A promising way of studying the Venusian environment involves the use of aerobots active in the benign region of the atmosphere. However, balloon missions to Venus, whether already conducted or just proposed, all suffer from very short mission life-time due to issues with sustained lifting.

Here, we present the VISTA mission concept. The mission concept proposes a solution to long-endurance aerobot flight on Venus through the use of in situ nitrogen extraction. The nitrogen content of the Venusian atmosphere in the convective cloud layer (50-60 km altitude) is about 3.5%. Obtaining nitrogen from the atmosphere can potentially provide a long-term supply of lifting gas, solving the unavoidable problem of lifting gas leakage. Greatly extended potential mission duration allows for much more extensive studies of the large scale wind patterns and detailed investigations of the atmosphere through time. It also enables the study of Venus’ interior, including detection of rare seismic events. The present work proposes a detailed mission concept for a long-term balloon-based aerobot that aims to uncover the mysteries of Venus. ... Read more

The assembly of discrete lattice structures using a climbing robot provides a flexible method for the assembly of efficient and large-scale structures. Automating the assembly of any goal structure, and allowing it to be applied to remote locations like the lunar surface, requires the robot to know in which order to place new lattice cells (voxels), and which path to take to get to these locations. For each robot step, which for a small structure can be well over 1000, the partially built structure that supports the robot needs to hold its own weight and the weight of the robot without failing. The inclusion of structural stability constraints in previous assembly sequence planning (ASP) methods for robotically assembled lattice structures is limited, making them suboptimal for structures with complex geometry like unsupported overhangs. Dealing with these structures requires the integration of structural analysis in addition to path planning in an ASP system which can create a plan consisting of assembly sequences and robot paths for the successful assembly of a structure. The plan should be compatible with the experimental setup, which uses magnetically linked 3D-printed PLA voxels of 10 cm in width, assembled by a five-degree-of-freedom robot. To achieve this, this thesis proposes an ASP system based on Ant Colony Optimization (ACO) capable of finding sequences and robot paths that ensure stable substructures throughout the course of the assembly. A path planner is developed to find the steps the robot needs to take to travel between two locations, as well as a FEM solver capable of calculating the internal loads within the lattice structure robot movement. These components are integrated into the Assembly sequence planner. This allows the planner to not only find sequences for simple structures, but also for more complicated structures by dynamically adding scaffolding in locations that need more structural support. The development of a dynamic ant quality function allows for the program to find sequences iteratively while simultaneously optimizing solutions for the minimum number of required scaffolding voxels. By testing this for a variety of different goal structures, one of which was built by the robot using the experimental setup, it is found that the ACO scheme is well suited for the robotic construction of these lattice structures. ... Read more

By breaking structures down into self-similar building blocks, digital manufacturing methods have come into the spotlight as a part of additive manufacturing. Progress in additive manufacturing has facilitated the production of more complex geometries and reduced material waste in the process. With the goal of scaling additive manufacturing up to the meso and macro scales, robotic assembly of cellular structures is increasingly being researched as a method to construct reconfigurable digital metamaterial structures. However, during robotic assembly and after the manufacturing is complete, the structural systems rely exclusively on external inputs if at all to estimate and monitor structural state. This thesis shows that the endemic robots used to manufacture the structure can also be used to measure deformations. The theoretical measurement characteristics of a bipedal inchworm robot have been calculated showing the expected resolution, accuracy, precision and dynamic range of measurements. Experiments have been conducted to construct a statistical measurement model and assess the nonlinearity of the measurement system. For a beam made up of 3D printed PLA cells with a relative density (p*/p) of 0.05, the results show that the robotic measurement system has resolution several times finer than the elastic range of bending and shear mode deformations for a beam with a single lattice cell cross-section. The robot can also detect stretch mode deformations on single lattice cross-section beams before structural failure. The thesis results demonstrate how inchworm locomoting bipedal assembly robots can be used to measure and monitor various deformations of slender lattice beams up to 3x3 cell cross-section, relying solely on the joint angle measurements used to control the robot. We anticipate this thesis to be a starting point for the integration of structural state measurements to the additive manufacturing process of robotic lattice cell assembly. ... Read more