PhD in Robotics
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– Oct 2017: I have defended my PhD Viva successfully on Friday, Oct 6th.
S.M.Hadi Sadati received his B.Sc. in Mechanical Engineering in 2010 from Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran, and his M.Sc. in Mechanical Engineering in 2012 from Sharif University of Technology, Tehran, Iran. In 2017, he received his Ph.D. in Robotics at King’s College London, University of London, London, UK. He is currently a Postdoctoral Research Associate in Morphological Computation at the University of Bristol, working within the Leverhulme Trust Research Project “Computing with spiders’ webs – An inspiration for new sensors and robots”. He also was a visiting researcher at Dyson School of Design Engineering at Imperial College London during 2017 and has been a member of IEEE Soft Robotics newsletter team since 2015. His research experience is in the fields of rescue robots, nonholonomic system path planning, dynamic system modeling, stiffness controllable continuum manipulators, and morphological computation and control. His research interests include bio-inspired robotics, morphological computation, continuum robotics, robot dynamics, control and design.
Description of Research
This thesis investigates how the problem of stiffness regulation of continuum manipulators can be simplified by inspiration from morphology of biological fish scales and experimental observation of manipulator geometry deformation.
Soft continuum “trunk and tentacle” manipulators have high inherent dexterity and reconfigurability and have become an attractive candidate for safe manipulation and explorations in surgical and space robotic applications recently. The passive shape adaptation and large reachable configuration space features of this class of manipulators, due to their highly deformable nature, make them a perfect choice for minimally invasive insertion of surgical tools in the confined maze-like space in many robotic surgery sites. However, achieving accuracy in precise tasks is a challenge with these highly flexible structures, for which stiffness variable designs based on jamming, smart material, antagonistic actuation and morphing structures are introduced in the recent years.
After a careful review and comparative study of current stiffness modeling and modulation of continuum manipulators, an analytical model is presented based on the geometry deformation of continuum manipulators and the Rivlin’s work on continuum media and adopted the Ritz and Galerkin methods to solve the dynamics of continuum manipulators based on Cosserat beam theory and principle of virtual work. Our new approach reduces model and control space dimension while preserving the accuracy. This enabled us to solve the stiffness regulation actuation and computation problems in the morphological level which highly simplifies the central control design.
Two novel integrable helical interfaces inspired by the shape and special arrangement of fish scales morphology is designed using tendon driven and thermo-active low melting point actuation mechanisms. High stiffness range, very low hysteresis and easy integration to different manipulator designs are the advantages of our design compared to the previous research. An analytical model is derived based on which the performance of the design is optimized. A comparison between the presented robotic interface designs and a real fish skin suggests that a passive scale jamming mechanism due to external stream and steady water pressure may help with improving the swimming locomotion performance.
Finally, a novel decentralized morphological approach is implemented to regulate the regional stiffness of the continuum manipulator integrated with the designed jamming interfaces to reject configuration disturbances and modulate the task space stiffness with application in soft tissue palpation.
- Control Space Reduction and Real-Time Accurate Modeling of Continuum Manipulators Using Ritz and Ritz-Galerkin Methods
S.M.Hadi Sadati, S. Elnaz Naghibi, Ian. D. Walker, Kaspar Althoefer, Thrishantha Nanayakkar. accepted in IEEE Robotics and Automation Letters (RA-L) Journal, 2017. PDF
- A Geometry Deformation Model for Braided Continuum Manipulators
S.M.Hadi Sadati, S. Elnaz Naghibi, Ali Shiva, Yohan Noh, Aditya Gupta, Ian. D. Walker, Kaspar Althoefer, Thrishantha Nanayakkar. Frontiers in Robotics and AI Journal, 2017. PDF
- Mechanics of Continuum Manipulators, A Comparative Study of Five Methods with Experiments
S.M.Hadi Sadati, S. Elnaz Naghibi, Ali Shiva, Ian D. Walker, Althoefer Kaspar, Thrishantha Nanayakkara. 18th Towards Autonomous Robotic Systems (TAROS) Conference, 2017. PDF
A Bio-Inspired Electro-Active Velcro Mechanism Using Shape Memory Alloy for Wearable and Stiffness Controllable Layers.
H. Afrisal and S.M.H. Sadati, T. Nanayakkara. Information and Automation for Sustainability (ICIAfS), 2016 8th International Conference on. IEEE, 2016. PDF
- A Geometry Deformation Model for Compound Continuum Manipulators with External Loading.
S.M.Hadi Sadati, Ali Shiva, Ahmad Ataka, Seyedeh Elnaz Naghibi, Ian Walker, Kaspar Althoefer, and Thrishantha Nanayakkara, IEEE International Conference on Robotics and Automation (ICRA), 2016. PDF
- Stiffness Control of Soft Robotic Manipulator for Minimally Invasive Surgery (MIS) Using Scale Jamming.
S.M.Hadi Sadati, Yohan Noh, S. Elnaz Naghibi, Althoefer Kaspar, and Thrishantha Nanayakkara. In Intelligent Robotics and Applications, pp. 141-151. Springer International Publishing, 2015. PDF
- An Automatic Algorithm to Derive Linear Vector Form of Lagrangian Equation of Motion with Collision and Constraint.
S. M. H. Sadati, S. E. Naghibi, and M. Naraghi. “An Automatic Algorithm to Derive Linear Vector Form of Lagrangian Equation of Motion with Collision and Constraint.” Procedia Computer Science 76 (2015): 217-222. PDF
- Passive dynamics of high frequency bat wing flapping with an anisotropic membrane.
Zheng, M., Sadati, S. M. H., Ghalamchi, P., & Nanayakkara, T. Information and Automation for Sustainability (ICIAfS), 2014 7th International Conference on. IEEE, 2014. (Winner of the Best Student Paper Award) PDF