Dr Lei RenBEng, MEng, PhD, FHEA, FRSA

Reader in Biomechanics and Biorobotics

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Expressions of interest are welcomed from potential PhD students. A list of possible research topics for PhD is provided below, organised by the main areas of my research. These are examples of relevant projects either recently started or currently in development. If you have any questions or ideas how to extend or compliment these topics, please get in touch!

 

Biomechanics

(1) Predictive Musculoskeletal Model to Simulate Human Walking

Human walking requires complex control between multiple body segments, joints and muscles, working in synchronization to provide impressive terrain adaptation, shock absorption and energy-efficient forward movement. The objective of this research is to develop a novel human musculoskeletal model, which can predict the complex segmental motions and muscle activities during human walking with minimal measurement inputs. This will be based on a very efficient combined multi-body dynamics and optimisation framework we have been developing over years, and will also be thoroughly validated against the gait measurement data collected using the state-of-the-art motion analysis system in our lab. A well-validated and robust predictive model would find many important practical applications. In clinical motion analysis, predictive models could be used to fully understand how different musculoskeletal structures and states of health or disease affect human walking. In surgical planning, the outcomes of surgical interventions can be foreseen by predictive musculoskeletal models before the surgeries. In rehabilitation engineering, predictive gait models could be used as part of a virtual prototyping approach to design for predicting the effects of new orthotic or prosthetic components on the biomechanics of walking. This would help reduce the costly and time-consuming reliance on physical prototyping and in-vivo testing.

(2) A Large-Scale Subject-Specific Finite Element Model of Human Foot Complex

The human foot is an immensely complex structure comprising numerous bones, muscles, ligaments and synovial joints. As the only body component in contact with the ground, it plays multiple crucial roles in attenuating ground impacts, maintaining locomotor stability, generating propulsive powers during locomotion. The objective of this study is to develop a large-scale subject-specific dynamic finite element (FE) model of the human foot musculoskeletal complex using the medical imaging based modelling technique we recently developed, which integrates the individualized medical imaging based modelling with the state-of-the-art in-vivo motion analysis technique. In this study, the three-dimensional musculoskeletal geometries of all the major muscles around ankle-foot complex will be precisely determined based on high resolution MRI scans. A multi-body dynamic ankle-foot complex model will be constructed to define the in-vivo subject-specific muscle activities. Finally, a subject-specific three-dimensional dynamic finite element foot model with detailed representation of all the major bones, muscles, tendons, ligaments and cartilages will be constructed with the ability to evaluate the biomechanical performance of the human foot complex during different motor activities. This would provide a very powerful tool for diagnosis and treatment of foot musculoskeletal diseases and also work as a virtual prototyping model to assess the footwear designs.

(3) Integrating Modelling, Motion Capture and X-Ray to Investigate the Osteoarthritic Knee Biomechanics

Knee osteoarthritis (OA) is a metabolically active, dynamic process that includes both destruction and repair mechanisms that can be triggered by mechanical insults. The objective of this research is to develop an in-vivo non-invasive framework by integrating musculoskeletal modelling, three-dimensional motion analysis technique and low-dose X-ray fluoroscopy to more comprehensively assess the in-vivo biomechanics of knee OA. The subject-specific musculoskeletal model of the lower limb will be developed from high resolution MRI imaging. The three-dimensional bone motions around the knee joint will be measured in sub-millimeter accuracy using the low-dose X-ray fluoroscopy. Highly complex 3-D dynamic simulations of musculoskeletal system movement will be conducted using a combined multi-body dynamics and optimization formulation. Finally, muscle loadings derived from these simulations will be applied to subject-specific finite element knee model to assess the dynamic loading conditions inside of the knee joint. By integrating this framework with properly designed cross-sectional studies of different levels of knee OA severity can provide important insight into the changing role of biomechanical factors throughout the progression of the disease.

(4) Multi-Scale Simulation of Human Musculoskeletal System

The human musculoskeletal system is an immensely complex system consisting of numerous bones, muscles, ligaments and synovial joints. The objective of this research is to develop a computational framework for multi-scale physical simulation of human musculoskeletal system. This involves the development of the subject-specific multi-body musculoskeletal model with efficient algorithm to simulate soft tissue deformations and mechanics simultaneously. Firstly, subject-specific musculoskeletal model will be constructed based on individualized MRI and CT medical imaging data and the anatomical structures using multi-body dynamics method. Thereafter, an efficient and robust mathematical algorithm to simulate soft tissue deformation and mechanics will be developed based on the continuum mechanics method with the main purpose being to simulate the musculoskeletal dynamics and soft tissue mechanics simultaneously. Human movement experiments using the three-dimensional motion analysis and force sensing techniques will be conducted to support and validate the modelling work. The final aim of the project is to develop a novel computational framework to conduct subject-specific musculoskeletal system modelling and simulation for medical practices and clinical diagnosis.

 

Biorobotics

(1) Development of a Humanoid Walking Robot Inspired by Human Musculoskeletal Biomechanics

The development of humanoid robots is a very challenging topic due to the intrinsic high-dimensionality and dynamic instability of the human locomotion. The most advanced bipedal robots nowadays still suffer high energy cost and poor dynamic stability. The objective of this research is to develop a humanoid bipedal robot with low energy requirement and intrinsic dynamic stability with structures and configurations inspired from human body. The structure of the robotics will be based on our recent research on human musculoskeletal biomechanics. The robotic design will involve careful design of different sub-component of the robot including foot complex, ankle joint, knee and hip joints, which will be based on the in-vivo physiological and anatomical data from human subjects. The controllers and actuators will be designed by a trial-and-error process by testing the minimal control sets of human locomotion and are also inspired from human gait measurement data. The whole system will finally be assembled and tested on both level and uneven ground surfaces. This will not only provide a solid and sound ground for the development of lower limb prosthetics, humanoid robots and also shed light on the fundamental biomechanical principles of human locomotion.

(2) Development of a Biomimetic Anthropomorphic Robotic Hand

Since the first industrial robot being proposed in the early 1960s, a great number of various robotic hands have been developed, which were more or less trying to imitating the function of human hand aiming to provide dexterous end-effectors for industrial or prosthetic use. This project arms to design a highly biomimetic anthropomorphic robotic hand that can closely replicate the human hand. The hand will be designed based on the investigation and understanding of the biomechanics and the anatomical structure of a human hand. The objectives for this project are: to investigate and understand the biomechanics and the anatomical structure of a human hand; to design a highly biomimetic anthropomorphic robotic hand that can highly replicate the phalanges, joints, ligaments and tendons of a human hand; to develop prototype of the proposed anthropomorphic robotic hand with rigid-flexible-coupled structures. This project involves design and prototype development, it is suitable for a student with mechanical engineering or biomechanics background who is interested in biomechanics and biorobotics.

(3) Development of a CNS-controlled Lower Limb Prosthesis Driven by Muscle EMG Signals

It has been reported that approximately 80% of all amputations in the world is on the lower extremity. With the wars and unrest affecting the world, the increase in vascular diseases contributing to amputations (e.g. diabetes etc.), and the continuous growth of the elderly population, the need for lower limb prostheses is on the rise. However, the availability of well-designed lower extremity prostheses, particularly those capable of reproducing the biomechanical functions of the absent biological limb, does not meet the demand. A successful CNS-controlled lower limb prosthetics, which is capable of fully restoring the biological functions of the healthy knee joint and ankle-foot complex, would greatly improve the locomotor efficiency, comfort and mobility of amputees. The purpose of this project is to develop and test the physical prototype and also the control strategy of a powered lower limb prosthetics based on lower limb muscle EMG signals and other gait derived signals. To achieve this, we are aiming the following tasks: 1. To conduct 3D gait measurements on 3 healthy subjects. 2. To investigate the mapping relationship between major thigh muscle EMG signals and lower limb joint torques. 3. To design and manufacture a physical prototype of lower limb prosthetics. 4. To develop a biologically inspired control strategy to drive the physical prototype based on muscle EMG signals and other gait derived signals (e.g. joint angles, ground reactions and gait event timings). 5. To test the physical prototype on amputee subjects under different walking conditions.

(4) A Biologically Inspired Exoskeleton System Capable of Enhancing Human Walking

Walking is the most frequent activity in our daily live. An exoskeleton that successfully modifies human gait to reduce joint loading, muscle fatigue, or metabolic demand of locomotion would have tremendous practical benefit to professionals burdened by load, to an aging population constrained by joint injury, or as a biomechanics research tool. While a number of exoskeletons have been built, few has demonstrated a significant reduction in the metabolic demand of locomotion. In this project, you will design and develop an innovative soft exoskeletal architecture for augmenting walking. A novel mechanical design for lower limb exoskeleton will be conducted and physically constructed inspired from human musculoskeletal mechanics by providing both joint flexibility and load bearing capacity. Experimental testing will be performed during human walking at various speeds.

(5) Biologically Inspired Soft Robots for Biomedical Applications

A soft robot is an engineered mobile machine that is largely constructed from soft materials. Most conventional robots are constructed from stiff materials such as steel, aluminum and plastics. They are usually powered directly by electric motors or by hydraulic fluids through rigid tubes. Such machines are capable of high speeds and great precision, making them very productive in factory assembly lines. However, very few of these machines can operate in natural environments or in close proximity to humans. To overcome some of these obstacles there is an increasing interest in building robots from soft materials. Our goal of soft robotics is to make machines that are adaptable and more creature-like in their capabilities by using soft active materials, advanced manufacturing techniques and biologically inspired designs. These robots may find many biomedical applications where the working environments are filled with variety and continuously changing conditions.