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Autonomous space robots are crucial for performing future in-orbit operations, including servicing of a spacecraft, assembly of large structures, maintenance of other space assets and active debris removal. Such orbital missions require servicer spacecraft equipped with one or more dexterous manipulators. However, unlike its terrestrial counterpart, the base of the robotic manipulator is not fixed in inertial space; instead, it is mounted on the base�spacecraft, which itself possess both translational and rotational motions. Additionally, the system will be subjected to extreme environmental perturbations, parametric uncertainties and system constraints due to the dynamic coupling between the manipulator and the base-spacecraft. This paper presents the dynamic model of the space robot and a three�stage control algorithm for this highly dynamic non-linear system. In this approach, feed�forward compensation and feed-forward linearization techniques are used to decouple and linearize the highly non-linear system respectively. This approach allows the use of the linear Proportional-Integral-Derivative (PID) controller and Linear Quadratic Regulator (LQR) in the final stages. Moreover, this paper covers a simulation-based trade-off analysis to determine both proposed linear controllers’ efficacy. This assessment considers precise trajectory tracking requirements whilst minimizing power consumption and improving robustness during the close-range operation with the target spacecraft.

Over the next two decades, unprecedented astronomy missions could be enabled by space telescopes larger than the James Webb Space Telescope. Commercially, large aperture space-based imaging systems will enable a new generation of Earth Observation missions for both science and surveillance programs. However, launching and operating such large telescopes in the extreme space environment poses practical challenges. One of the key design challenges is that very large mirrors (i.e. apertures larger than 3m) cannot be monolithically manufactured and, instead, a segmented design must be utilized to achieve primary mirror sizes of up to 100m. Even if such large primary mirrors could be made, it is impossible to stow them in the fairings of current and planned launch vehicles, e.g., SpaceX’s Starship reportedly has a 9m fairing diameter. Though deployment of a segmented telescope via a folded-wing design (as done with the James Webb Space Telescope) is one approach to overcoming this volumetric challenge, it is considered unfeasible for large apertures such as the 25m telescope considered in this study. Parallel studies conducted by NASA indicate that robotic on-orbit assembly (OOA) of these observatories offers the possibility, surprisingly, of reduced cost and risk for smaller telescopes rather than deploying them from single launch vehicles but this is not proven. Thus, OOA of large aperture astronomical and Earth Observation telescopes is of particular interest to various space agencies and commercial entities. In a new partnership with Surrey Satellite Technology Limited and Airbus Defence and Space, the Surrey Space Centre is developing the capability for autonomous robotic OOA of large aperture segmented telescopes. This paper presents the concept of operation and mission analysis for OOA of a 25m aperture telescope operating in the visible waveband of the electromagnetic spectrum; telescopes of this size will be of much value as it would permit 1m spatial resolution of a location on Earth from geostationary orbit. Further, the conceptual evaluation of robotically assembling 2m and 5m telescopes will be addressed; these missions are envisaged as essential technology demonstration precursors to the 25m imaging system.

Off-road ground mobile robots are widely used in diverse applications, both in terrestrial and planetary environments. They provide an efficient alternative, with lower risk and cost, to explore or to transport materials through hazardous or challenging terrain. However, nongeometric hazards that cannot be detected remotely pose a serious threat to the mobility of such robots. A prominent example of the negative effects these hazards can have is found on planetary rover exploration missions. They can cause a serious degradation of mission performance at best and complete immobilization and mission failure at worst. To tackle this issue, the work presented in this paper investigates the novel application of an existing enhanced-mobility locomotion concept, a hybrid wheel-leg equipped by a lightweight micro-rover, for in situ characterization of deformable terrain and online detection of nongeometric hazards. This is achieved by combining an improved vision-based approach and a new ranging-based approach to wheel-leg sinkage detection. In addition, the paper proposes an empirical model, and a parametric generalization, to predict terrain trafficability based on wheel-leg sinkage and a well-established semiempirical terramechanics model. The robustness and accuracy of the sinkage detection methods implemented are tested in a variety of conditions, both in the laboratory and in the field, using a single wheel-leg test bed. The sinkage-trafficability model is developed based on experimental data using this test bed and then validated onboard a fully mobile robot through experimentation on a range of dry frictional soils that covers a wide spectrum of macroscopic physical characteristics.

Path planning and collision avoidance are two crucial interconnected algorithms used to perform desired tasks for both fixed and moving base manipulators. In this paper, the collision-free trajectory generation algorithm presented for capturing a stationary target is a newer form of the state-of-the-art method using cycloids. It is further optimised to minimise the distance between the obstacle and the manipulator. A control algorithm using the Computed Torque Control to accurately track the pre-designed trajectory is discussed. The simulations results presented in this paper verify the efficacy and robustness of the controller based on the non-linear dynamical model of the robotic manipulator. The optimised collision-free trajectory resulted in smooth joint displacement, velocity and acceleration. Moreover, the algorithm presented can be applied to ground based and space based stationary or moving robotic manipulators.

© 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim. This paper is on the design, fabrication, and testing of skins and sleeves for soft robotics with the focus on the mechanical features of the microstructure of these skins, drawing inspiration from nature and architecture. Biological inspirations drawn from animals are used for designing skin membranes or skin structures for soft robotic actuators, in particular pneumatic actuators that protect, guide, and contribute to the development of the actuated shape. The results presented in this paper will be a new step toward advancing the state-of-the-art of biologically inspired soft robots for minimally invasive surgery. Inspirations from architecture are of particular interest in the areas of formability of design and continuous flow. The report presents a trade-off study using various skin and sleeve technologies of innovative fiber structures and combinations of different materials in different innovative designs, surrounding a pneumatically actuated, soft robot of variable stiffness.

This paper investigates different types of crimped, braided sleeve used for a soft arm for robotic abdominal surgery, with the sleeve required to contain balloon expansion in the pneumatically actuating arm while it follows the required bending, elongation and diameter reduction of the arm.Three types of crimped, braided sleeves from PET (BraidPET) or nylon (BraidGreyNylon and BraidNylon, with different monofilament diameters) were fabricated and tested including geometrical and microstructural characterisation of the crimp and braid, mechanical tests and medical scratching tests for organ damage of domestic pigs.BraidPET caused some organ damage, sliding under normal force of 2-5 N; this was attributed to the high roughness of the braid pattern, the higher friction coefficient of polyethylene terephthalate (PET) compared to nylon, and the high frequency of the crimp peaks for this sleeve. No organ damage was observed for the BraidNylon, attributed to both the lower roughness of the braid pattern and the low friction coefficient of nylon. BraidNylon also required the lowest tensile force during its elongation to similar maximum strain as that of BraidPET, translating to low power requirements.BraidNylon is recommended for the crimped sleeve of the arm designed for robotic abdominal surgery.