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(Nixon) Tung Fai Yu 余東徽

MEng (Hons) Electronics Engineering, PhD Physics

Note: Nixon has now moved on to work in the department of Physics electronics workshop as an electronics engineer. Link


Position: Full-time PhD research student, 2009 to 2013

PhD Project Title:

Mathematical Models of Human Muscles for the Support of Rehabilitation Using
Functional Electrical Stimulation

Keywords: Human muscles, Hill models, musculo-skeletal, biomechanics, motion capture, parameter estimation

Nixon joined the medical physics team in the Department of Physics in October 2009, and started his course under the supervision of Professor Adrian Wilson. His project is funded by the EPSRC.

The main areas of work are:
1) Developing mathematical models of human muscles and musculo-skeletal system.
2) Parameterise the models using measurements of human movement obtained using the Gait Lab (see below).

Functional Electrical Stimulation (FES) is used in movement rehabilitation strategies for regaining muscle functions and movements, such as standing. However most FES control systems lacked details of individual muscle characteristics, which limited the system's ability to cope with physiological effects such as muscle fatigue. Clinically, the lack of anatomical and physiological meaningful parameters in the system, caused difficulties in adjusting the system to address muscle disease progression. These calls for the need of anatomical and physiological meaningful muscle models to support the design of FES control systems.
The theoretical Hill muscle (Hill 1938) is a well-known model with anatomical and physiological meanings, and many variations exist, but there are little published numerical values of these muscle model parameters, for which the reason was unknown.

Through structural identifiability analysis, the classical Hill muscle model was found to be structurally unidentifiable. A structurally identifiable modified version: the Yu muscle model was developed, which has anatomic and physiological meanings, and each model component has geometrical definition. A set of experimental protocal was developed, which allowed the model to be applied to human muscles in vivo, and the parameters in the model to be parameterised using measurement of human movement obtained in the Gait Lab.

The exeprimental protocal were sucessful and provided data to allow unique model parameter values to be obtained through model fitting.

The current on going work is to design FES experiments in combination with the Yu muscles models to obtain a model based FES control system prototype.


2005-2009 Nixon studied at the University of Warwick for his undergraduate degree, where he graduated with a 1st in Masters of Electronics Engineering.

Summer 2008 Nixon took a work placement in the MedPhys group, in which he designed and built electronics equipments for Md Naimul Islam's PhD project. The equipments included a programmable multi-frequency current source and a high gain amplifier (x1000 gain). This placement led him to join the MedPhys group after his MEng degree to undertake his PhD training.

The Gait Laboratory, installed in August 2009, houses a Vicon MX motion capture system, which can record movement, ground reaction force and muscle EMG. The images below are of some equipments in the Gait Lab and the data in which the system can record.


Gait Laboratory - Vicon real time motion capture system (pictured by Mabel Cheng)


Study of human balance during quiet standing

Recent News

29th September 2012 - 8th IFAC Symposium on Biological and Medical Systems

Nixon Yu attended IFAC BMS 2012, 8th IFAC Symposium on Biological and Medical Systems in Budapest, Hungary. Nixon gave a poster and oral presentation titled "A Novel Passive Movement Method for Parameter Estimation of a Musculo-skeletal Arm Model Incorporating a Modified Hill Muscle Model". The poster was awarded best poster.

14th September 2011 - EMBEC 2011, 5th European Conference of the International Federation for Medical and Biological Engineering

Nixon Yu and Prof. Adrian Wilson attended EMBEC 2011, 5th European Conference of the International Federation for Medical and Biological Engineering in Budapest, Hungary. Nixon gave an oral presentation titled "Structural Identifiability Analysis and Preliminary Parameter Estimation for an Arm Model Incorporating the Hill Muscle Model"
The submitted paper can be found here.

22nd October 2010 - Physics Postgraduate Student Staff Liaison Committee

Nixon Yu has been elected as chair of Physics PG-SSLC for the academic year 2010 - 2011. The website for Physics PG-SSLC is:

13th September 2010 - Gregynog Hall, University of Wales, Teamworking and Networking Residential Course

A facebook group has been created for all who went to the team working and networking course in Wales in Septmber, for people to network easier, and also share some photos from the event.

Click this link to go to the facebook group.

*The University, creaters and editors of the Warwick websites are not resposnible for the content of external Internet sites.


18th august 2010 - ScienceSnaps Photo Competition Winners Announced

"The Human Gait in Digital Form" has been selected as one of six winning entries into the ScienceSnaps photo compeition.

The competition is organised between Birmingham and Warwick University, to generate awareness in science in school children and the general public.

For more information about the whole campaign and to view the full size image and other entries, go to:


Contact Details:

Write to:
Tung Fai Yu
Department of Physics
University of Warwick

44 (0)24 765 74207