Chris Melhuish

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Papers by Chris Melhuish

Compliance Control and Human–Robot Interaction: Part II — Experimental Examples

International Journal of Humanoid Robotics, Sep 1, 2014

Compliance control is highly relevant to human safety in human robot interaction (HRI). This pape... more Compliance control is highly relevant to human safety in human robot interaction (HRI). This paper presents multi-dimensional compliance control of a humanoid robot arm. A dynamic model-free adaptive controller with an anti-windup compensator is implemented on four degrees of freedom of a humanoid robot arm. The paper is aimed to compliment the associated review paper on compliance control. This is a model reference adaptive compliance scheme which employs end-effector forces (measured via joint torque sensors) as a feedback. The robot's body-own torques are separated from external torques via a simple but effective algorithm. In addition, an experiment of physical human robot interaction is conducted employing the above mentioned adaptive compliance control

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A Real-Time, FPGA Based, Biologically Plausible Neural Network Processor

Lecture Notes in Computer Science, 2005

Abstract. A real-time, large scale, leaky-integrate-and-fire neural net-work processor realized u... more

Collective sorting and segregation in robots with minimal sensing

Many ants sort their brood so that brood items at similar stages of development are grouped toget... more Many ants sort their brood so that brood items at similar stages of development are grouped together, and separated from items at different stages of development. Brood items are moved individually. The only model proposed to date assumes that ants engaged in brood sorting can sense both the type of element they are carrying, and the local spatial density of that type of element; the model was demonstrated in simulation using two types of objects. This paper describes a system of simple homogeneous autonomous mobile robots which are able to segregate or sort two types of physically identical objects differing only in colour, yet can sense only the colour of the object they are carrying, and have no capacity for spatial orientation or memory. This shows that this sorting problem can be solved by agents simpler than was previously supposed possible.

Feature Identification forTexture Discrimination from Tactile Sensors

Towards Autonomous Robotic Systems (TAROS)

A Hardware Based Implementation of a Tactile Sensory System For Neuromorphic Signal Processing Applications

2006 IEEE International Conference on Acoustics Speed and Signal Processing Proceedings

The implementation of a tactile sensory system for neuromorphic signal processing applications is... more The implementation of a tactile sensory system for neuromorphic signal processing applications is presented. It has been developed by modelling the structure and behaviour of real rodent facial vibrissae. The primary afferents have been modelled using empirical data taken from electrophysiological measurements, and implemented in real time using hardware processors (DSP/FPGA). Pipelining techniques were employed to maximise the utility of

Creating annular structures inspired by ant colony behaviour using minimalist robots

IEEE International Conference on Systems, Man and Cybernetics

Abstract - This study shows that a task as complicated as multi-objezt &amp;amp;#x27;ant-like... more Abstract - This study shows that a task as complicated as multi-objezt &amp;amp;#x27;ant-like annular sorting&amp;amp;#x27; can be accomplished with a &amp;amp;#x27;minimalist&amp;amp;#x27; solution employing a simple mechanism and minimal hardware. The success of the mechanism, which employs a combined leaky ...

An optimal sliding mode controller applied to human motion synthesis with robotic implementation

Proceedings of the 2010 American Control Conference, 2010

The operational space formulation is applied to a practical robot system in order to generate rea... more The operational space formulation is applied to a practical robot system in order to generate realistic human reaching motion based on the minimisation of `effort&amp;amp;amp;amp;amp;amp;#39;, a function of gravity and weighting gains. We present a novel optimal sliding mode controller that uses techniques of steepest descent to achieve this minimisation without affecting the task controller. The sliding mode optimal controller

Underactuated fingers controlled by robust and adaptive trajectory following methods

International Journal of Systems Science, 2012

Choosing an appropriate control scheme to alleviate nonlinearities and uncertainties is not a tri... more Choosing an appropriate control scheme to alleviate nonlinearities and uncertainties is not a trivial task, especially when models are not easily available and practical evaluation provides the only means for actual performance assessment. Various factors can contribute to these nonlinearities and uncertainties, such as friction and stiction. Thus, this article investigates four different control schemes, namely PID, adaptive, conventional sliding

Cerebellar-Inspired Adaptive Control of a Robot Eye Actuated by Pneumatic Artificial Muscles

IEEE Transactions on Systems, Man, and Cybernetics, Part B (Cybernetics), 2009

In this paper, a model of cerebellar function is implemented and evaluated in the control of a ro... more In this paper, a model of cerebellar function is implemented and evaluated in the control of a robot eye actuated by pneumatic artificial muscles. The investigated control problem is stabilization of the visual image in response to disturbances. This is analogous to the vestibuloocular reflex (VOR) in humans. The cerebellar model is structurally based on the adaptive filter, and the learning rule is computationally analogous to least-mean squares, where parameter adaptation at the parallel fiber/Purkinje cell synapse is driven by the correlation of the sensory error signal (carried by the climbing fiber) and the motor command signal. Convergence of the algorithm is first analyzed in simulation on a model of the robot and then tested online in both one and two degrees of freedom. The results show that this model of neural function successfully works on a real-world problem, providing empirical evidence for validating: 1) the generic cerebellar learning algorithm; 2) the function of the cerebellum in the VOR; and 3) the signal transmission between functional neural components of the VOR.

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Extracting textural features from tactile sensors

Bioinspiration & Biomimetics, 2008

This paper describes an experiment to quantify texture using an artificial finger equipped with a... more This paper describes an experiment to quantify texture using an artificial finger equipped with a microphone to detect frictional sound. Using a microphone to record tribological data is a biologically inspired approach that emulates the Pacinian corpuscle. Artificial surfaces were created to constrain the subsequent analysis to specific textures. Recordings of the artificial surfaces were made to create a library of frictional sounds for data analysis. These recordings were mapped to the frequency domain using fast Fourier transforms for direct comparison, manipulation and quantifiable analysis. Numerical features such as modal frequency and average value were calculated to analyze the data and compared with attributes generated from principal component analysis (PCA). It was found that numerical features work well for highly constrained data but cannot classify multiple textural elements. PCA groups textures according to a natural similarity. Classification of the recordings using k nearest neighbors shows a high accuracy for PCA data. Clustering of the PCA data shows that similar discs are grouped together with few classification errors. In contrast, clustering of numerical features produces erroneous classification by splitting discs between clusters. The temperature of the finger is shown to have a direct relation to some of the features and subsequent data in PCA.

Ants can sort their brood without a gaseous template

Behavioral Ecology and Sociobiology, 2005

A fundamental issue of collective intelligence is whether the collective pattern or process is ba... more A fundamental issue of collective intelligence is whether the collective pattern or process is based on environmental information that explicitly codes for it or arises through self-organization of the individuals. Sometimes, these alternatives occur together. Adaptive systems may also be capable of utilizing different types of mechanism under different conditions. Sendova-Franks et al. (Anim Behav 68:1095-1106, 2004) demonstrated evidence for a self-organization mechanism of brood sorting in the ant Temnothorax albipennis, where the brood are sorted in a series of bands or concentric annuli that increase in size with distance from the colony centre. The work by Cox and Blanchard (J Theor Biol 204:223-238, 2000) suggests an alternative or complementary mechanism whereby the brood pattern is specified by the template of a CO 2 gradient. Here, we test for a gaseous template as a necessary condition for brood sorting. Under the experimental condition, we pumped the air out of the nest continuously to prevent the accumulation of any gaseous substances. We compared the brood pattern between the experimental and control conditions according to four characteristics: mean distance from centre, mean nearest-neighbour distance, shape and area. Under the experimental condition, the order of brood types according to the first two characteristics was the same as in the control. The area of the brood pattern was smaller, and its shape elongated under the experimental condition. As expected on the basis of these differences, mean distance from centre was greater and mean nearest-neighbour distance was smaller under the experimental condition (although not statistically significantly) and by the expected amount. We found evidence that ants avoid placing brood in the strongest airflow stream. This could explain the reduced area and elongated shape of the brood pattern under the experimental condition. We conclude that a gaseous template is not a necessary condition for brood sorting.

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Low cost ultrasonic positioning system for mobile robots

Proceeding of Towards Autonomous Robotic Systems, Sep 1, 2007

This paper describes a simple low-cost 2D and 3D positioning system for mobile robots. The system... more This paper describes a simple low-cost 2D and 3D positioning system for mobile robots. The system makes use of both ultrasound and radio frequency signals to achieve positional accuracies better than 1% of the tracked volume. Furthermore, we have integrated the positioning system into the simulation tools Player/Stage, in order to combine simulated robots with real robots in a 'hybrid'embodied simulation. The paper presents measurements from using the positioning system for both 3D tracking and 3D closed loop control.

Comparisons in Evolution and Engineering: The Collective Intelligence of Sorting

Adaptive Behavior, 2004

Collaboration between biologists and roboticists can facilitate the creation of new behavioral al... more Collaboration between biologists and roboticists can facilitate the creation of new behavioral algorithms by roboticists and help biologists by exposing the underlying mechanisms that allow the algorithms to function (for a review see Webb, 2000). This paper makes a direct comparison between robot annular puck sorting using real robots (Wilson, Melhuish, Sendova-Franks & Scholes, 2004) and brood sorting in the ant Leptothorax albipennis (Franks & Sendova-Franks, 1992). We compared the ants’ and robots’ structures in terms of radial displacement, shape, compactness, completeness and separation. This showed the effectiveness and limitations of using metrics developed for robots to quantify structures built by ants and helped relate common aspects of the structures to possible common aspects of the underlying algorithms. The ant behavioral rule set is still under investigation and a better understanding of the structure it creates has proved a very useful tool to examine aspects of the...

Improved power and long term performance of microbial fuel cell with Fe-N-C catalyst in air-breathing cathode

Energy, Feb 1, 2018

Power output limitation is one of the main challenges that needs to be addressed for full-scale a... more Power output limitation is one of the main challenges that needs to be addressed for full-scale applications of the Microbial Fuel Cell (MFC) technology. Previous studies have examined electrochemical performance of different cathode electrodes including the development of novel iron based electrocatalysts, however the long-term investigation into continuously operating systems is rare. This work aims to study the application of platinum group metals-free (PGM-free) catalysts integrated into an airbreathing cathode of the microbial fuel cell operating on activated sewage sludge and supplemented with acetate as the carbon energy source. The maximum power density up to 1.3 Wm À2 (54 Wm À3) obtained with iron aminoantipyrine (Fe-AAPyr) catalyst is the highest reported in this type of MFC and shows stability and improvement in long term operation when continuously operated on wastewater. It also investigates the ability of this catalyst to facilitate water extraction from the anode and electroosmotic production of clean catholyte. The electrochemical kinetic extraction of catholyte in the cathode chamber shows correlation with power performance and produces a newly synthesised solution with a high pH > 13, suggesting caustic content. This shows an active electrolytic treatment of wastewater by active ionic and pH splitting in an electricity producing MFC.

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微生物燃料電池‐重金属の電気凝集のための新しい自己出力型廃水電解槽【Powered by NICT】

International Journal of Hydrogen Energy, 2017

Miniature microbial fuel cells and stacks for urine utilisation

International Journal of Hydrogen Energy, 2013

ABSTRACT MFCs are becoming a stronger contender in the area of alternative energy sources and sho... more ABSTRACT MFCs are becoming a stronger contender in the area of alternative energy sources and show great promise in utilising a wide variety of organic sources. This paper describes the utilisation of neat undiluted urine as the main feedstock for different types of individual MFCs and stacks of small-scale MFCs, for direct electricity production, with conversion efficiencies of &gt;50%. The smallest MFC (1.4 mL total volume) produced equal amounts of power to that produced by larger MFCs (6.25 mL), resulting in increased power densities. Power densities of 4.93 mW/m2 (absolute power of 1.5 mW) were recorded when 48 small-scale MFCs were connected as a stack and fed with urine. This study demonstrates the feasibility of using urine as an untreated fuel and that improved power outputs can be achieved through MFC miniaturisation and multiplication into stacks.

An Oxygen-Diffusion Cathode MFC Model for Simulation of Energy-Autonomous Robots

We present a macroscopic mathematical model of energy generation dynamics in oxygen-diffusion cat... more

Stereo Computer Vision as an aid to Blind Mobility

Manipulating objects with gliders in cellular automata

Micro-scale manipulation of objects is a growing requirement in specialised industries, especiall... more 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.

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Compliance Control and Human–Robot Interaction: Part II — Experimental Examples

International Journal of Humanoid Robotics, Sep 1, 2014

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A Real-Time, FPGA Based, Biologically Plausible Neural Network Processor

Lecture Notes in Computer Science, 2005

Abstract. A real-time, large scale, leaky-integrate-and-fire neural net-work processor realized u... more