Parachutes and inflatable structures: Parametric comparison of EDL systems for the proposed vanguard Mars Mission

Vanguard is a proposed post-Beagle2 mission to Mars focussed on astrobiology, but also on technology demonstration [1]. The 120 kg probe is assumed to use a Mars-Express- type bus to land a triad of robotics comprising a lander, a rover and 3 penetrating moles. The landed mass is around 65 kg. The mission is baselined to be low-cost with limited power and mass requirements to be accommodated as a secondary payload on a future mission to Mars [2]. Here the Entry, Descent and Landing system (EDLS) is investigated comparing conventional methods (hard heatshield/Parachute) to current new developments in inflatable entry structures as demonstrated by missions such as IRDT and IRDT2. Two systems are designed to provide an understanding of EDLS requirements in term of masses and volumes to land a small probe safely on Mars. Preliminary results [3] show that, despite the heritage, a conventional approach is heavier than inflatable technologies. Indeed, in this particular case, a margin of about 15 % is derived in favour of the inflatable system. For a constant-mass probe, this means that the mass is saved from the EDLS to the benefit of the payload. Moreover, despite having a larger range, and longer descent, in this case the inflatable option has in this case a wind gust sensitivity comparable to the parachute option

Design concepts and implementation of the Lightweight Advanced Robotic Arm Demonstrator (LARAD)

Beyond the current ExoMars programme, the European Space Agency (ESA) is investigating a range of technology developments and exploration mission opportunities leading to a future Mars Sample Return Mission (MSR), a critical next in the exploration of Mars. To fulfil their scientific objectives, all of these missions require an arm with a long reach capable of performing a variety of tasks in stringent environmental conditions, such as low gravity sampling and precise sample handling and insertion. As part of a CREST-2 project supported by the UK Space Agency (UKSA), a consortium of UK companies have co-founded and developed LARAD, a new Lightweight Advanced Robotic Arm Demonstrator to address some of the underlying challenges related both to the design as well as operation of long arms to perform the payload deployment and sample return operations of future missions. The 15kg terrestrial demonstrator is built as a 2m long arm with 6 degrees of freedom. This arm is capable of deploying a payload with a mass up to 6kgs or operating a 4kg end-effector at 2m. It is using cutting edge technologies on both the hardware and software levels. The mechanical structure of the arm has been manufactured using an array of new processes such as optimised 3D printed titanium Additive Layer Manufactured (ALM) joints, Titanium/Silicon carbide metallic composites, and 3D printed harness routing drums. A modular joint design has been produced, featuring three mechanical sizes of joints each with integrated low level communication and motor drive. The electronics, software and sensors used in the joints are common across all sizes, increasing modularity. To achieve precise positioning, very high resolution absolute position sensing is used on-board. The arm uses novel collision avoidance and path-planning strategies combined with classical control loops. The On-board Control System?s state machine combines different control strategies/modes (i.e. joint trajectory tracking, direct motor control, autonomous placement) depending on the high level user operation requirements. The high level On Board Computer (OBC) is Robot Operating System (ROS) based, enabling a flexible software approach. This project will provide a unique and representative platform to plan and rehearse science operations with full mass payload and instruments, unlike typical planetary arm developments that require scaled-mass end-effector. This paper describes the current state-of-the-art in planetary robotics and provides an overview of the top-level architecture, implementation and laboratory testing phases for the LARAD robotic arm.Peer reviewe

ANUBIS: artificial neuromodulation using a Bayesian inference system

Gain tuning is a crucial part of controller design and depends not only on an accurate understanding of the system in question, but also on the designer's ability to predict what disturbances and other perturbations the system will encounter throughout its operation. This letter presents ANUBIS (artificial neuromodulation using a Bayesian inference system), a novel biologically inspired technique for automatically tuning controller parameters in real time. ANUBIS is based on the Bayesian brain concept and modifies it by incorporating a model of the neuromodulatory system comprising four artificial neuromodulators. It has been applied to the controller of EchinoBot, a prototype walking rover for Martian exploration. ANUBIS has been implemented at three levels of the controller; gait generation, foot trajectory planning using Bézier curves, and foot trajectory tracking using a terminal sliding mode controller. We compare the results to a similar system that has been tuned using a multilayer perceptron. The use of Bayesian inference means that the system retains mathematical interpretability, unlike other intelligent tuning techniques, which use neural networks, fuzzy logic, or evolutionary algorithms. The simulation results show that ANUBIS provides significant improvements in efficiency and adaptability of the three controller components; it allows the robot to react to obstacles and uncertainties faster than the system tuned with the MLP, while maintaining stability and accuracy. As well as advancing rover autonomy, ANUBIS could also be applied to other situations where operating conditions are likely to change or cannot be accurately modeled in advance, such as process control. In addition, it demonstrates one way in which neuromodulation could fit into the Bayesian brain framework