Copyright © 2017 ISCA. This paper introduces MiRo-The world's first commercial biomimetic robot-And describes how its vocal system was designed using a real-Time parametric general-purpose mammalian vocal synthesiser tailored to the specific physical characteristics of the robot. MiRo's capabilities will be demonstrated live during the hands-on interactive 'Show & Tell' session at INTERSPEECH-2017

Mitchinson, B.

Moore, R.K.

White Rose Research Online

This is a repository copy of Creating a voice for MiRo, the world's first commercial biomimetic robot.White Rose Research Online URL for this paper:http://eprints.whiterose.ac.uk/128436/Version: Published VersionProceedings Paper:Moore, R.K. orcid.org/0000-0003-0065-3311 and Mitchinson, B. (2017) Creating a voice for MiRo, the world's first commercial biomimetic robot. In: Proceedings of the Annual Conference of the International Speech Communication Association, INTERSPEECH 2017. Interspeech 2017, 20-24 Aug 2017, Stockholm, Sweden. ISCA , pp. 3419-3420. © 2017 ISCA. Reproduced in accordance with the publisher's self-archiving policy.eprints@whiterose.ac.ukhttps://eprints.whiterose.ac.uk/Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version - refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher’s website. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Creating a Voice for MiRo,the World’s First Commercial Biomimetic RobotRoger K. Moore1, Ben Mitchinson21Speech & Hearing Research Group, Dept. Computer Science, University of Sheffield, UK2Dept. Psychology, University of Sheffield, UKr.k.moore@sheffield.ac.uk, b.mitchinson@sheffield.ac.ukAbstractThis paper introduces MiRo - the world’s first commercialbiomimetic robot - and describes how its vocal system wasdesigned using a real-time parametric general-purpose mam-malian vocal synthesiser tailored to the specific physical charac-teristics of the robot. MiRo’s capabilities will be demonstratedlive during the hands-on interactive ‘Show & Tell’ session atINTERSPEECH-2017.Index Terms: biomimetic robot, MiRo, mammalian vocalisa-tion, vocal synthesis1. IntroductionRecent years have seen growing interest in the use of animal-like robots for a range of applications such as assistance, com-panionship, pet therapy and edutainment. The majority of suchdevices are engineered to support specific use-cases, and oftenit is only the robot’s physical appearance that mimics a partic-ular animal. In contrast, MiRo (designed and built by Conse-quential Robotics Ltd. in collaboration with the University ofSheffield [1]) is the first commercial robot to be controlled byhardware/software modelled on the biological brain [2, 3].MiRo is a highly featured, low-cost, programmable mobiledeveloper platform, with a friendly animal-like appearance, sixsenses, a nodding and rotating head, moveable hearing-ears,large blinking seeing-eyes, and a responsive wagging tail. It hasbeen designed to look like a cartoon hybrid of a generic mam-mal - see Fig. 1. MiRo is suited for developing ‘companion’robots - future social robots that will share our personal space,interact with us and with each other and provide emotional en-gagement and entertainment. A unique brain-based biomimeticcontrol system allows MiRo to behave in a life-like way: forexample, listening for sounds and looking for movement, thenapproaching and responding to physical and verbal interactions.MiRo’s control architecture is outlined in Section 2.Of particular interest here is MiRo’s ability to vocalise.This was achieved using a real-time parametric general-purposemammalian vocal synthesiser [4] tailored to the physical andbehavioural characteristics of the robot [5]. The design ofMiRo’s voice is summarised in Section 3.2. MiRo’s Control ArchitectureMiRo’s control architecture operates across three embeddedARM processors that mimic aspects of spinal cord, brainstemand forebrain functionality - see Fig. 2. One important featureis that the control latency of loops through the lowest repro-grammable processor can be as low as a few milliseconds. Ifrequired, MiRo can be operated remotely through WiFi or Blue-tooth, and can also be configured as a Robot Operating System(ROS) node.Figure 1: The MiRo biomimetic robot.2.1. ActuatorsMiRo is constructed around a differential drive base and a neckwith three ‘degrees of freedom’ (DoF). Additional DoFs includerotation for each ear, tail droop and wag, and eyelid open/close.All DoFs are equipped with proprioceptive sensors, and theplatform also has an on-board loudspeaker.2.2. SensorsMiRo is equipped with stereo cameras in the eyes, stereo micro-phones in the ears and a sonar range-finder in the nose. Fourlight-level sensors are placed at each corner of the base, andtwo infrared ‘cliff’ sensors point down from its front. Eight ca-pacitive sensors are arrayed along the inside of the body shell,over the top of the head and behind the ears. Internal sensorsinclude twin accelerometers, a temperature sensor and battery-level monitoring.2.3. AffectMiRo represents its affective state (emotion, mood and tempera-ment) as a point in a two-dimensional space covering ‘valence’(unpleasantness-pleasantness) and ‘arousal’ (calm-excited) [6].Events arising in MiRo’s sensorium are mapped into changesin affective state: e.g., stroking MiRo drives valence in a posi-tive direction, whilst striking MiRo on the head drives valencein a negative direction. Baseline arousal is affected by gen-eral sound/light levels and the time of day. An individual eventcan cause an acute change: e.g., a very loud sound might raisearousal and decrease valence. MiRo’s movements are modu-lated by its affective state, and it expresses itself using a set of‘social pattern generators’ that drive light displays, movementof the ears, tail, eyelids and - of particular importance here -vocalisation.Copyright  2017 ISCAINTERSPEECH 2017: Show & Tell ContributionAugust 20–24, 2017, Stockholm, Sweden3419Figure 2: Illustration of MiRo’s control architecture looselymapped onto brain regions (spinal cord, brainstem, forebrain).Signal pathways are excitatory (open triangles), inhibitory(closed triangles), or complex (closed circles). BG is the BasalGanglia. SPG/MPG are the Social/Motor Pattern Generators.3. MiRo’s VoiceA special requirement of MiRo’s design was that its voiceshould be ‘appropriate’ to the biomimetic nature of the robot.Hence, rather than using a fixed inventory of pre-recorded an-imal sounds, MiRo’s ability to vocalise was developed usinga general-purpose mammalian vocal synthesiser [4] tailored tothe specific physical characteristics of the robot [5]. The ap-proach taken was to decompose the overall sound productionsystem into the relevant anatomical components (body, lungs,vocal cords, tongue and mouth), and to model each compo-nent within a real-time parametrically-controlled sound genera-tor. The net result is that every vocalisation is both appropriateand unique.3.1. Synthesis SoftwareThe overall structure of the synthesis software is based on asimulation of the flow of energy through a generic mammalianvocal apparatus with body mass corresponding to an animal ofMiRo’s size. The key modules correspond to the lungs, larynxand vocal tract. The robot has a breathing rhythm, the frequencyof which is linked to arousal (see Section 2.3), and vocalisationis initiated stochastically during the exhalation phase. Breath-ing is simulated as cyclic airflow into and out of the lungs withan amplitude and duration that is calculated from the flow rate,lung capacity and body mass. When vocalising, the larynx mod-ulates the airflow using the simulated action of a set of vocalfolds vibrating at a fundamental frequency that is also deter-mined by the body mass. The vocal tract then simulates threeacoustic resonances (formants) using band-pass filters whosefrequencies are determined by the vocal tract length and the de-gree of mouth opening. A syllabic rate parameter controls theopening and closing of the mouth, and a vibrating uvula adds a‘cute’ robotic timbre to the voice.3.2. Vocal EmotionIn order to allow the injection of emotion into the vocalisations,key parameters were linked to MiRo’s two-dimensional affectmap (as discussed in Section 2.3). Arousal modulates the air-flow rate and, thereby, the amplitude and tempo of the vocalisa-tions; high arousal leads to high airflow and short vocalisations(and vice versa). Valence influences the variance of the fun-damental frequency and the voice quality; high valence leadsto expressive vocalisation whereas low valence produces moremonotonic utterances. For example, stroking MiRo’s head in-creases valence, which leads to ‘happier’ vocalisations (and awagging tail).4. ConclusionThis paper has introduced MiRo - the world’s first commercialbiomimetic robot - and described how its vocal system wasdesigned using a real-time parametric general-purpose mam-malian vocal synthesiser tailored to the specific physical charac-teristics of the robot. MiRo’s capabilities will be demonstratedlive during the hands-on interactive ‘Show & Tell’ session atINTERSPEECH-2017.5. AcknowledgementsThis work was partially supported by the European Commis-sion [grant numbers EU-FP6-507422, EU-FP6-034434, EU-FP7-231868 and EU-FP7-611971], and the UK Engineeringand Physical Sciences Research Council (EPSRC) [grant num-ber EP/I013512/1].6. References[1] MiRo: The Biomimetic Robot. [Online]. Available:http://consequentialrobotics.com/miro/[2] B. Mitchinson and T. J. Prescott, “MiRo: A robot mammal with abiomimetic brain-based control system,” in Biomimetic and Bio-hybrid Systems. Living Machines 2016. Lecture Notes in Com-puter Science, N. Lepora, A. Mura, M. Mangan, P. Verschure,M. Desmulliez, and T. Prescott, Eds. Springer, 2016, vol. 9793,pp. 179–191.[3] E. C. Collins, T. J. Prescott, B. Mitchinson, and S. Conran, “MiRo:a versatile biomimetic edutainment robot,” in Proceedings of the12th International Conference on Advances in Computer Enter-tainment Technology - ACE ’15. Iskandar, Malaysia: ACM Press,2015, pp. 1–4.[4] R. K. Moore, “A real-time parametric general-purpose mammalianvocal synthesiser,” in INTERSPEECH, San Francisco, CA, 2016,pp. 2636–2640.[5] R. K. Moore and B. Mitchinson, “A biomimetic vocalisationsystem for MiRo,” in Living Machines 2017, Stanford, CA, 2017.[Online]. Available: http://arxiv.org/abs/1705.05472[6] E. C. Collins, T. J. Prescott, and B. Mitchinson, “Saying it withlight: a pilot study of affective communication using the MiRorobot,” in Proceedings of the 4th International Conference onBiomimetic and Biohybrid Systems - Volume 9222. Barcelona,Spain: Springer-Verlag New York, Inc., 2015, pp. 243–255.3420

Creating a voice for MiRo, the world's first commercial biomimetic robot

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Creating a voice for MiRo, the world's first commercial biomimetic robot

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