My research at SUTD started as a natural continuation of my doctoral research, which was on the design of magnetic sensing assemblies for direct magnetic-field based localization in industrial applications. Through enhancements of the accuracy and computational speed of field-based localization and capitalizing the benefits of magnetic fields in the clinical environment, I was able to acquire research grants that focus on adapting passive magnetic fields for localization of medical instruments. Recently the technology and patents that I have developed over the years in passive magnetic localization has been licensed to a company for commercialization. While this domain has been my core area during the earlier years, I have managed to expand the application of magnetic fields to robotics and automation. It was at this juncture that I diversified to unmanned aerial system designs but the link to magnetic fields still holds strong, where the nature inspired rotor crafts currently under development rely on the Earth’s geomagnetic field for localization and control.
My current main research focus are:
- Designing innovative, high performance localization technology & systems through intelligent harnessing of passive magnetic fields, and
- Dynamic analysis, sensing, control and development of novel robotics and unmanned platforms using design principles.
In the realm of magnetic sensing, I have continued to advocate for and pushed the limits for passive magnetic technology. Most localization or tracking systems available commercially operate on the principle of electromagnetic induction. These systems consist of an external source that generates a low energy time-varying magnetic field in and around the area of interest while miniaturized coils are attached to the target of interest (also called moving-sensor-stationary-source configuration). Due to Faraday’s law of induction, electrical signals are induced in these coils within this externally generated field. The magnitude of these signals allows the absolute position and orientation of the coils (and therefore the catheter) to be determined with respect to the external field. The main issue with this approach is that the sensor on the moving target needs to be energized or tethered, which makes it cumbersome or unsuitable for a number of potential medical and robotic applications. Passive magnetic sensing is an emerging viable alternative to this approach. Here the configuration is flipped into a moving-source-stationary-sensors system where the target of interest is now accompanied by a small permanent magnet. Through measurement of the magnetic field, the orientation and position of the magnet and hence the target (such as a tube) can be computed. This approach also has the advantage of not requiring any auxiliary power or tethering to the target as the magnetic field is passively generated.
In this domain, I have advanced the state-of-art in a number of areas:
- Enhanced operational localization accuracy and computational speed (for real-time operation) through advanced magnetic field models, biologically inspired optimization of magnetic and sensor assemblies, augmented mathematical inverse algorithms for real-time operation and performing noise characterizations and filtering (Best Application Paper Award). Two patents, US20160086080 and US20160287134 were filed based on these research.
- Adapted and applied the technology for real-world robotics and medical applications. One direct application of magnetic sensing is adapting it for a high force, compact force sensor for a robotic quadruped. In this novel lightweight magneto-elastomeric sensor, applied force is converted into displacement through mechanical elastic deformation. This resultant deformation, in multiple axes, can be determined in 2D/3D using a network of magnetic sensors. Through direct modelling, the magnetic field measurement can be directly correlated to applied force. Because magnetic sensing is non-mechanical, it is extremely robust and can withstand shocks, making it highly suitable as a high-impact, high range force sensor.
In addition, the use of passive magnetic technology for real-time monitoring of the nasogastric tube has successfully completed an impressive and highly successful R&D cycle. It was first conceived as a potential research project with the National University of Hospital (NUH) in 2012 and was successfully funded by the SUTD-MIT International Design Centre (IDC) in 2013. While laboratory testing and trials were being carried out, a technology disclosure was filled in late 2013 and a full patent was filed in 2014. Biological testing soon followed in 2015 with an accompanying publication in the Annals of Biomedical Engineering Journal in 2015 as well. In early 2016, cadaveric trials of the system was initiated with great success and finally in 2017, the technology has been licensed to Medergo Pte. Ltd. for commercialization of: Smart FeedTM: Safer Nasogastric (NG) Enteral Feeding Solution. Currently I am a technical advisor to Medergo Pte. Ltd. assisting in the continued development of the system.
Another area which I have started to contribute keenly to is in the area of bespoke aerial robotics. In particular, hybrid quadrotor-fixed wing unmanned aerial vehicles (UAVs) are of growing interest due to ability to cruise over large distances and yet exhibit VTOL capabilities which is especially important in urban environments. However the wing area and propulsion units on most current hybrid UAVs are still used exclusively for fixed-wing flight and do not function during VTOL mode, and vice versa. Hence a large majority of these designs are inherently inefficient. Inspired by the Sycamore maple seed leaf (Acer pseudoplatanus) and the Vine maple seed leaf (Acer circinatum) which are seeds attached to one and two wings respectively, I have advocated for development of a novel hybrid UAV that incorporates the dispersal mechanism of the maple seed into the UAV design. While UAVs based on the Sycamore Maple leaf have been explored (sometimes called monocopters or samara-UAVs), a variant based on the Vine Maple is the focus of my research. This proposed hybrid UAV, called the Transformable HOvering Rotorcraft (THOR), has been uniquely engineered to combine the range and speed of a horizontal flying platform with the hovering and manoeuvrability of a rotor-wing. This is achieved by integrating a tailless flying wing configuration with a single-axis rotor, or monocopter. This design, unlike any other hybrid UAV, maintains full utilization of all aerodynamic surfaces and propulsion sources in both flight modes and represents the most structurally efficient approach to achieving a cruising mode and a hovering mode on the same frame. A key feature of THOR as well as any rotor-based craft is the inherent ability to autorotate, which allows the UAV to glide to the ground even if power to the propulsion system is lost.
Some preliminary contributions to this emerging area are:
- Design optimization and operational concept of a dual-wing transformable rotorcraft that maintains full utilization of all propulsion sources and aerodynamic surfaces in VTOL and cruise flight modes. This includes geometrical optimization of the wing twist and chord length for hovering flight and autorotation performance respectively.
- Dynamic modelling, sensing and control of the hybrid transformable rotorcraft which includes characterizing and verifying the gyroscopic precession effects of the platform and developing a high range gyroscope using dual accelerometers to overcome operational limit of commercial gyroscopes.
Funded Research Projects
- Integrative Distributed Field-Based Sensing and Control of Halbach Inspired Electromagnetic Devices, Singapore University of Technology & Design (SUTD), Start-Up Grant (SRG), Principal Investigator
- Development of an Automatic and Configurable Non-invasive System for Enhanced Transcranial Magnetic Stimulation (TMS), SUTD, SUTD-ZJU Research Collaboration Grant, Principal Investigator
- Harnessing Passive Magnetic Fields for Image-guided Navigation of Ventriculostomy Catheters and other Intracranial Instrumentation, Agency for Science Technology & Research (A*STAR), A*STAR-CIMIT Joint Research Grant, Principal Investigator
- Real-time Non-Invasive Magnetic Field-Based Localization of Nasogastric Tube, SUTD-MIT International Design Centre (IDC), Research Grant, Principal Investigator
- Algorithm for Design of Compliant Mechanisms, SUTD-MIT IDC, Research Grant, Principal Investigator
- Work Package 5: Adaptation of a Task-Orientated Agile Workcell, Agency for Science Technology & Research (A*STAR), A*STAR-SERC Research Grant – Industrial Robotics Programme, Co-Investigator
- Base Development for Systems Technology for Autonomous Reconnaissance & Surveillance, Future Systems Technology Directorate (FSTD), Ministry of Defence Singapore (MINDEF), SUTD Temasek Labs Research Grant, Principal Investigator
- Development of a High Yield Automated Marine Rearing System, Singapore-MIT Alliance for Research & Technology (SMART) Innovation Centre, Ignition Grant, Principal InvestigatorIntroductory Aero Drone Design Workshop by SUTD, Civil Aviation Authority of Singapore (CAAS), CAAS Aviation Youth Outreach Seed Fund, Principal Investigator
- Taking Designettes to the Next Level: Aerial Craft Design Workshop, SUTD-MIT IDC, Pilot Grant, Principal Investigator
- Design and Development Of A Highly Maneuverable Propulsion System In An Unmanned Surface Vehicle For The Maritime RobotX Challenge, US Office of Naval Research, Broad Agency Announcement, Principal Investigator
- Design and Development of an in-situ Early Blood Leakage Detection Device, SUTD – Changi General Hospital (CGH), Healthtech Innovation Fund, Principal Investigator
- Project GRUIDAE: Aerial UAV show for SG50, Temasek Laboratories (TL) @ SUTD, Seed Research Project Grant, Principal Investigator
- Vertical Take-off and Landing (VTOL) with Autonomous Rapid Exfiltration (rescue) Abilities, Gilmour Space Technologies, External Industry Grant, Principal Investigator
- SG50 Aerial Craft Design & Development, DSO National Laboratories, SG50 External Sponsorship, Principal Investigator
- Flight Test Analysis of Aerospoke Nozzle Designs, TL @ SUTD, Seed Research Project Grant, Principal Investigator
Large-scale 3D Printing/robotics; additive repair, SUTD Digital Manufacturing and Design (DManD) Centre, Research Grant, Principal Investigator
- Fusion of Additive & Subtractive Manufacturing Processes, SUTD DManD Centre, Research Grant, Principal Investigator
- Paper 3D Printing, SUTD-MIT IDC, Pilot Grant, Co-Investigator
- Conception, Design & Development of a Design-Centric Student Competition (IDC Robocon 2015 and SUTD Technology & Design Challenge 2016), SUTD-MIT International Design Centre (IDC), Pilot Grant, Principal Investigator
- Advancing UAV Concepts & Development for Operation in GPS Denied Environments, SUTD-MIT IDC, Research Grant, Principal Investigator
- Kyanite: Improved Cognitive Performance by Design, FSTD, MINDEF, Defence Innovative Research Programme (DIRP), Collaborator
- Design and development of pressure ulcer prevention device customized for Accident & Emergency environment, SUTD-CGH, Healthtech Innovation Fund, Co-Investigator
- Real-time motion compensation platform for ultrasound-guided surgical procedures – Percutaneous nephrolithotomy for renal stone treatment, SUTD-CGH, Healthtech Innovation Fund, Co-Investigator
- Research, Design and Development of Modular Electric Propulsion Systems for Multi-Propeller VTOL Vehicle Applications (Leo Jeoh), Economic Development Board (EDB), IPP-EDB Project (Airbus Helicopters Southeast Asia Pte Ltd ), Principal Investigator
- MONOCO:Nature Inspired Single Rotor Aerial Crafts, FSTD, MINDEF, Defence Innovative Research Programme (DIRP), Principal Investigator
- Human-machine interface and technology development for collaborative control of unmanned systems, Defence Science & Technology Agency (DSTA), External Industry Grant, Co-Investigator
- S-Drone : Mini Unmanned Aerial Vehicle (UAV) for Surveillance, Singapore Technologies Electronics (InfoComm Systems), External Industry Grant, Principal Investigator
- A Smart Unmanned Aerial Vehicle Based Imaging System for Inspection of Deep Hazardous Tunnels, National Research Foundation (NRF) – Public Utilities Board (PUB), Environment and Water Industry (EWI) Programme, Principal Investigator
- Developing a Light, Low Cost and Low Risk Micro Unmanned Aerial System (mUAS) for Tree Inspections, National Parks Board (NParks), External Industry Grant, Principal Investigator
- A Multi-Source Semantic 3D Modeling Platform for Virtual Singapore, NRF, Virtual Singapore Grant Call, Co-Investigator
- Singapore’s Tangible Heritage in Virtual and Augmented Reality, National Heritage Board (NHB), Heritage Research Grant (HRG), Co-Investigator
- Cost Effective Large Scale 3D Printing for the Industrial Sector with Locally Developed Hybrid WAAM Technology, National Additive Manufacturing Innovation Cluster (NAMIC) @ SUTD, Research Grant, Co-Investigator
- Automated Inspection and Cleaning of Sheltered Link Ways Using Smart Unmanned Aerial Vehicles (UAVs), Land Transport Authority (LTA), Land Transport Innovation Fund (LTIF) , Principal Investigator