Dr Ketao Zhang
BSc, PhD, FHEA

Research Overview

Dr Ketao Zhang's research interests focus on (i) Computational kinematics, (ii) design innovation, including bio-inspired and origami-inspired engineering design; (iii) aerial robotics and multi-agent systems, (iV) reconfigurable/metamorphic robots and morphable soft-bodied robots; and (V) their applications in digital manufacturing, assistive robotic devices in health care, and inspection/observing in challenging environments. 

Main research themes within the Robotic Systems Research Group include:

• Computational kinematics
• aerial robotics  
• reconfigurable robots/manipulators and applications
• origami and morphable soft-bodied robots
• design, modelling and control of novel legged robots

Highlights of research outcomes and contributions 

1. Reconfigurable/metamorphic parallel manipulators 

Robot mechanisms research is a fundamental study with strong science elements. My early work on reconfigurable mechanisms is a piece of fundamental research aimed at investigating the characteristics of reconfigurability of a class of novel mechanisms that can adapt to various tasks and environments. The pioneering study revealed underlying principles of metamorphosis and proposed mathematical modelling for the topological reconfiguration based on graph theory, screw algebra and line geometry. This led to the invention of the variable-axis (vA) joint and development of a class of reconfigurable mechanisms, including the 3-SvPS parallel mechanism that can be used as structure of a reconfigurable robotic machine center with adaptability to changing task requirements. 

Selected references:

W. Ye, X. Chai and K. Zhang, "Kinematic Modeling and Optimization of a New Reconfigurable Parallel Mechanism." Mechanism and Machine Theory, 2020 DOI10.1016/j.mechmachtheory.2020.103850.

K. Zhang, J. S. Dai, Y. Fang, Topology and Constraint Analysis of Phase Change in the Metamorphic Chain and Its Evolved Mechanism, ASME Transactions, Journal of Mechanical Design, 132(12), p. 121001, 2010.

2. Morphable and continuum robots 

The recent crossdisciplinary study on origami and kinematic structure opens new trends of research on foldable mechanisms and evolved flexible robots, especially on the design methodology and manufacturing process for constructing three-dimensional active structures from two-dimensional flat-sheet models. In contrast to the conventional mechanisms, the origami-inspired systems have distinct flexibility and foldability which are expected in real-world applications. The emerging development of origami-inspired mechanical systems showed that knowledge of origami in artistic discipline is capable of being well applied in a wide range of areas in engineering such as architecture design and fabrication of smart robotic systems. The interdisciplinary study on both origami and kinematic structure presented an interesting approach to identifying new mechanical embodiment of intricate origami. My work in this area led to unique mathematical approaches for modelling kinematics and statics of various foldable structures in terms of screw theory by aggregating folding characteristics of individual creases. In particular, the motion of panels and creases of origami-inspired structures were investigated by identifying the constraints of creases taken as compliant joints. This in-depth unravelling of principles and approaches for modelling origami structures resorting to mechanism theory in the engineering discipline provides fundamental bases for the development of novel concepts and manufacturing techniques of origami-inspired systems.

Selected references:

K. Zhang, C. Qiu, J. S. Dai, An Extensible Continuum Robot with Integrated Origami Parallel Modules, ASME Transactions, Journal of Mechanism and Robotics, 8(3), 031010, 2016.

M. Salerno, K. Zhang, A. Menciassi, J. S. Dai, A Novel SMA Actuated 4-DOF Origami Grasper for Minimally Invasive Surgery, IEEE Transactions on Robotics. 32(3), pp. 484-498, 2016.

K. Zhang, C. Qiu, J. S. Dai, Helical Kirigami-Enabled Centimetre-Scale Worm Robot with Shape-Memory-Alloy Actuators, ASME Transactions, Journal of Mechanism and Robotics, 7(2), 021014, 2015.

3. Mechanism Design of Legged Mobile Robots

Among the mobile robotic research field, legged locomotion is largely applied for advanced robotic systems due to the higher degree of versatility compared to wheeled robots, which allows them to successfully move and interact in unstructured environments.  Legged robots present several designing challenges, particularly leg mechanism design is very complex from a mechanical point of view and requires a study of all factors responsible for locomotion dynamics. Drawing inspiration from fast running animals, we developed  novel leg structures that can exploit the walking gait dynamics and achieve optimized balance between velocity, dexterity and energy efficiency. 

Selected references:

S Asci, K Zhang, Design and Kinematic Simulation of a Novel Leg Mechanism for Multi-Legged Robots. ASME IDETC2021.