Ioannis Georgilas

A variable compliance, soft gripper

Autonomous grasping is an important but challenging task and has therefore been intensively addressed by the robotics community. One of the important issues is the ability of the grasping device to accommodate varying object shapes in order to form a stable, multi-point grasp. Particularly in the human environment, where robots are faced with a vast set of objects varying in shape and size, a versatile grasping device is highly desirable. Solutions to this problem have often involved discrete continuum structures that typically comprise of compliant sections interconnected with mechanically rigid parts. Such devices require a more complex control and planning of the grasping action than intrinsically compliant structures which passively adapt to complex shapes objects. In this paper, we present a low-cost, soft cable-driven gripper, featuring no stiff sections, which is able to adapt to a wide range of objects due to its entirely soft structure. Its versatility is demonstrated in several experiments. In addition, we also show how its compliance can be passively varied to ensure a compliant but also stable and safe grasp.

Cellular automaton model of crowd evacuation inspired by slime mould

In all the living organisms, the self-preservation behaviour is almost universal. Even the most simple of living organisms, like slime mould, is typically under intense selective pressure to evolve a response to ensure their evolution and safety in the best possible way. On the other hand, evacuation of a place can be easily characterized as one of the most stressful situations for the individuals taking part on it. Taking inspiration from the slime mould behaviour, we are introducing a computational bio-inspired model crowd evacuation model. Cellular Automata (CA) were selected as a fully parallel advanced computation tool able to mimic the Physarum’s behaviour. In particular, the proposed CA model takes into account while mimicking the Physarum foraging process, the food diffusion, the organism’s growth, the creation of tubes for each organism, the selection of optimum tube for each human in correspondence to the crowd evacuation under study and finally, the movement of all humans at each time step towards near exit. To test the model’s efficiency and robustness, several simulation scenarios were proposed both in virtual and real-life indoor environments (namely, the first floor of office building B of the Department of Electrical and Computer Engineering of Democritus University of Thrace). The proposed model is further evaluated in a purely quantitative way by comparing the simulation results with the corresponding ones from the bibliography taken by real data. The examined fundamental diagrams of velocity–density and flow–density are found in full agreement with many of the already published corresponding results proving the adequacy, the fitness and the resulting dynamics of the model. Finally, several real Physarum experiments were conducted in an archetype of the aforementioned real-life environment proving at last that the proposed model succeeded in reproducing sufficiently the Physarum’s recorded behaviour derived from observation of the aforementioned biological laboratory experiments.

Design of an advanced prototype robot for white asparagus harvesting

Agricultural workplaces are a prototypical example of unstructured and variant environments, offering a novel challenge to robotic research and automation. In this paper, a robot prototype is presented for white asparagus harvesting. White asparagus is a rather delicate vegetable with unique cultivation characteristics, which is exceptionally tiring and laborious to collect and requires specialized workers for harvesting. In this paper, we propose an integrated robotic system able to move in the field, identify white asparagus stems and collect them without damaging them. We highlight the design decisions for every module of the harvester and outline the overall architecture of the system.

Preliminary analysis of force-torque measurements for robot-assisted fracture surgery

Our group at Bristol Robotics Laboratory has been working on a new robotic system for fracture surgery that has been previously reported [1]. The robotic system is being developed for distal femur fractures and features a robot that manipulates the small fracture fragments through small percutaneous incisions and a robot that re-aligns the long bones. The robots controller design relies on accurate and bounded force and position parameters for which we require real surgical data. This paper reports preliminary findings of forces and torques applied during bone and soft tissue manipulation in typical orthopaedic surgery procedures. Using customised orthopaedic surgical tools we have collected data from a range of orthopaedic surgical procedures at Bristol Royal Infirmary, UK. Maximum forces and torques encountered during fracture manipulation which involved proximal femur and soft tissue distraction around it and reduction of neck of femur fractures have been recorded and further analysed in conjunction with accompanying image recordings. Using this data we are establishing a set of technical requirements for creating safe and dynamically stable minimally invasive robot-assisted fracture surgery (RAFS) systems.

Towards an intelligent distributed conveyor

Manipulation, orientation and handling of components, subparts and finished products is an essential element of any industrial process, which attracts substantial portion of resources and infrastructure. Classic manipulation, e.g. robot arms, is not always efficient at the micro-scale and suffers in terms of scaleability. We are proposing an alternative concept of manipulation based on an array of actuators. The proposed system rely on the natural concepts of scaleability and parallelism: ciliary motion and excitable media control.

Design and real-time control of a robotic system for fracture manipulation.

This paper presents the design, development and control of a new robotic system for fracture manipulation. The objective is to improve the precision, ergonomics and safety of the traditional surgical procedure to treat joint fractures. The achievements toward this direction are here reported and include the design, the real-time control architecture and the evaluation of a new robotic manipulator system. The robotic manipulator is a 6-DOF parallel robot with the struts developed as linear actuators. The control architecture is also described here. The high-level controller implements a host-target structure composed by a host computer (PC), a real-time controller, and an FPGA. A graphical user interface was designed allowing the surgeon to comfortably automate and monitor the robotic system. The real-time controller guarantees the determinism of the control algorithms adding an extra level of safety for the robotic automation. The systems positioning accuracy and repeatability have been demonstrated showing a maximum positioning RMSE of 1.18 ± 1.14mm (translations) and 1.85 ± 1.54° (rotations).

UAV Horizon Tracking Using Memristors and Cellular Automata Visual Processing

Unmanned Aerial Vehicles (UAV)s can control their altitude and orientation using the horizon as a reference. Typically this task is performed via edge-detection vision processing techniques implemented in a computer or digital electronics. We demonstrate a proof-of-principle for a memristive cellular automata (CA) system which can simply interface with an analog electronic control system. Our aim is a cheaper, lighter and more robust low-level system. Low-quality, noisy and wide-angle images consistent with cheap cameras have been tested and, even with these issues, the system can recognise the tilt angle and express it as relative activation of cells at the edge of a CA which could be used to drive motors to right the aircraft.

Manipulating objects with gliders in cellular automata

Micro-scale manipulation of objects is a growing requirement in specialised industries, especially those related to assembly of fragile micro-components. Widely implemented techniques in robotics and automation do not always cope with the delicate nature of the process. To improve the micro-scale manipulators we consider both hardware and software issues, and focus on designing massive-parallel embedded controllers for non-trivial actuating surfaces. This paper offers an initial insight on cellular automata (CA) gliders control of a smart surface. A brief presentation of the prototype hardware will be given along with a justification on the selection of manipulated objects. The formulation of the excitable CA lattice is presented and experimental data is analysed. The results support the capabilities of a fully distributed CA controlled massive parallel manipulation architecture.

Image-based robotic system for enhanced minimally invasive intra-articular fracture surgeries

Robotic assistance can bring significant improvements to orthopedic fracture surgery: facilitate more accurate fracture fragment repositioning without open access and obviate problems related to the current minimally invasive fracture surgery techniques by providing a better clinical outcome, reduced recovery time, and health-related costs. This paper presents a new design of the robot-assisted fracture surgery (RAFS) system developed at Bristol Robotics Laboratory, featuring a new robotic architecture, and real-time 3D imaging of the fractured anatomy. The technology presented in this paper focuses on distal femur fractures, but can be adapted to the larger domain of fracture surgeries, improving the state-of-the-art in robot assistance in orthopedics. To demonstrate the enhanced performance of the RAFS system, 10 reductions of a distal femur fracture are performed using the system on a bone model. The experimental results clearly demonstrate the accuracy, effectiveness, and safety of the new RAFS system. The system allows the surgeon to precisely reduce the fractures with a reduction accuracy of 1.15 mm and 1.3°, meeting the clinical requirements for this procedure.

Metachronal waves in cellular automata:Cilia-like manipulation in actuator arrays

Paramecium is covered by cilia. It uses the cilia to swim and transport food particles to its mouth. The cilia are synchronised into a collective action by propagating membrane potential and mechanical properties of their underlying membrane and the liquid phase environment. The cilia inspired us to design and manufacture a hardware prototype of a massively parallel actuator array, emulated membrane potentials via a discrete excitable medium controller and mechanical properties based on vibrating motors. The discrete excitable medium is a two-dimensional array of finite automata, where each automaton, or a cell, updates its state depending on states of its closest neighbours. A local interaction between the automata lead to emergence of propagating patterns, waves and gliders. The excitable medium is interfaced with an array of actuators. Patterns travelling on an automaton array manifest patterns of actuation travelling along the array of actuators. In computer models and laboratory experiments with hardware prototypes we imitate transportation of food towards mouth pore of the Paramecium. The hardware actuator arrays proposed could in future replace simple manipulators in demanding micro-scale application.