Research and Work experience

My research is mainly focussed on 1. understanding human response and behavior of human being by applying enginnering and technological concepts in Human system Engineering; and 2.Application of the knowledge in design and development of systems and service in Human Factors Engineering, in our lab - Human Engineering Research Lab (HER Lab). We are working in interdisciplinary areas. In product design area, I am mainly focus on Assistive device design.

• Work on National Importance

1. Recommended Weight Limit (RWL) of manual material liftling for Indians

In 1991, NIOSH has declared RWL of Manual Material Handling (MMH) for adult American population as 23 kg based on epidemiological and experimental studies on manual lifting activities. Similarly, my doctoral study is the first scientific study reported in India to determine recommended weight limit (RWL) during manual material handling (MMH) for Indian female workers based on Physiological, Biomechanical and Psychophysical criteria and RWL is determined to be 15 kg, and thereby for the male to be 18 Kg due to better physical capacity. Related work is published in international journals. Based on ILO publication Maximum weights in load lifting and carrying which provides for 15 kg as the limit, recommended from an ergonomic point of view for women aged between 19 and 45 years old.

Research Lab :

Human Engineering Research Lab (HER Lab)

Editorial Board Member :

International Journal of Industrial Ergonomics

Elsevier

Contacts:

+91-80-2293-3134/2359

email: rmaiti@iisc.ac.in

2. Modelling of Thermal sensation response of Indians

National Building Code of India (BIS, 2005) advocates the use of two indoor temperature ranges for summer (23–26)^oC and winter (21–23)^oC for all the climatic zones, which is similar to ASHRAE recommendation. However, India is a tropical country and researchers reported the adaptive behaviour of the occupants. In a laboratory set-up thermal responses from 40 healthy Indian college student are measured in terms of regional skin temperature and oral temperature at differentroom temperaturevarying from (21–33)^oC and the estimated thermal comfort zone is obtained as (23.5–26.5)^oC. Thermal sensation deals with how we feel thermally (viz. hot, cool etc.) our ambientenvironment. ASHRAE has proposed the relationship between PMV (Predicted Mean Vote, a quantitative measure ofthermal sensation based on ambient parameters and subjective parameters) and PPD (Predicted PercentageDissatisfaction, a quantitative measure of percentage of people dissatisfied with the thermal condition) follows a symmetric thermal response curvebetween hot (PMV - 0 to +3) and cold ambient temperature (PMV - 0 to -3). PMV is analogus for Thermal Sensation Vote (TSV), collected directly from the subjects. For the first time, from this study, it has been shown that Indians are more hot adaptive (i.e. slow response curve in hot region) than the cold environment, due to the tropical adaptation.

Physical Product Design

(Working prototype development)

• Stroke rehabilitative device,
• Exercise Device for Cerebral palsy,
• Exerciser for paraplegics,
• Exerciser for cerebral palsy
• Mobility assistive device for paraplegics,
• Design of Laparoscopic tool,
• Exergaming station for cerebral palsy,
• Towing device for 2-wheelers,
• Learning aid for visually challenged kid
• Assistive device for dysgraphia
• Smart mobility aid for visually challenged
• Bedridden patient transfer device
• Patient turning device
• Stroke rehabilitation in Hands
• Smart chair to reduce fatigue
• Assistive device for dimnetia
• Assistive device in controlling Parkinson's tremor
• Bamboo strip remover - Hand tool

Our work is mainly focussing on following areas:

• Biosensors and Clinical engineering
• Biomedical digital signal processing (DSP)
• Image processing
• Automobile engineering - safety and comfort
• Consitutive model, joint biomechanics, Orthotics & Prosthetic design
• Indoor Thermal Analysis and Thermal Comfort
• Assistive Device design

1. Understanding muscle fatigue during dynamic contraction (part of research work):

To study the muscle system behavior in a non-invasive way, different signal processing techniques are applied on sEMG signal based on certain assumptions on the signal. In laboratory, subjects were asked to lift a weight till completely they exhausted and their EMG were collected for analysis. EMG signal was analyzed based on different types of signal processing techniques: 1. Linear and stationary signal processing techniques like, Periodogram, Welch Periodogram and Sort Term Fourier Transform (STFT); 2. Linear and non-stationary signal processing techniques like Auto-Regression (AR) based spectral analysis, Wigner-Ville Distribution (WVD), Pseudo Wigner-Ville Distribution (PWVD), Smoothed Pseudo Wigner-Ville Distribution (SPWVD), Choi-William Distribution (CWD) and Continuous Wavelet Transform (CWT); and 3. Non-linear and non-stationary signal processing techniques like Huang Hilbert Transform (HHT), Approximate Entropy (ApEn), Fuzzy Approximate Entropy (fApEn) and Recurrence Quantification Analysis (RQA). Result showed non-linear and non-stationary signal processing techniques provide better estimating parameters than others. Wavelet results were also promising.

2. Muscle dynamics using multi-electrode array; new EMG electrode development (Part of a project)

In present study, the multi-electrode recording of sEMG during isometric contraction of Biceps Brachii with sampling frequency of 500 samples.sec^-1. From the shift in signal pattern the muscle conduction velocity is calculated.

My Drawings with frame

An attempt was made to fabricate a durable, stable, and reproducible Ag/AgCl bio-potential electrode. sEMG electrode (Ag-Agcl electrode) is made by electro-deposition technique. The electrode base is made in-house and sEMG is recorded and compared with the ENG recorded using electrode provided by BIOPAC Inc.

3. Peak strength measurement and Maximum Voluntary Contraction (MVC) study

In this study, peak strength was measured in different simulated field postures during manual load lifting and performed MVC study of the primary muscles related to these postures.

4. Biomechanical modelling of Skeletal muscle (Research work ongoing)

This study aims to formulate the mechanical equivalent model to accurately predict the value of generated force function especially during transient isometric muscle contraction using MATLAB. In transient isometric contraction, probabilistic contribution at any time instance between different states of Actin-Myosin binding process and their temporal relationship in equilibrium condition are being studied.

5. Measurement of Parkinson’s Tremor and assistive device design (Project work)

Both Essential Tremor (ET) and Parkinson’s Disease (PD) are adult-onset movement disorders and share similar clinical symptoms.Distinguishing essential tremor from Parkinson’s disease is challenging and often create diagnostic confusion, both in the early stages of these diseases and as these diseases progress. Various tremor types (rest, postural, kinetic and intention) may be seen in both essential tremor and Parkinson’s disease. Detailed carefule quantification on specific features of tremor (frequency, amplitude, pattern and distribution) and associated neurological findings with classification of neuroimaging data may help distinguish patients with the two diseases. In addition, gyroscope based assistive device design is started to reduce the tremor and helps to bring up self-dependency and morale of affected patients

6. Maximum Aerobic Capacity measurement, Lung Function test and static body anthropometry measurement

During doctoral studies various body parameters were recorded in the laboratory to understand the different body parameters of the adult female construction workers.

7. Human body joint biomechanics and Gait analysis:

Calculation of different joint reaction force, moments and kinematics measurements in different postures will help in better understanding of both joint function and dysfunction, resulting in design improvements of devices such as joint arthroplasty systems and orthotic devices etc. Basic knowledge in musculoskeletal biomechanics is useful in a critical evaluation of current or newly proposed patient evaluations and treatments. Joint biomechanics study was done during manual load lifting and walking.

8. Constitutive modeling of knee joints and FE analysis (part of research work):

Constitutive modeling of knee joint with Tibia, Femur, cartilage and menisci is developed from MRI images. Medical images are processed with image intensity adjustment, anisotropic diffusion filter with egde preservation and then edge detection. Option for manual correction is provided at the discontinuous detected edge boundary points for better bone boundary extraction especially at the inhomogeneous intensity with very poor contrast areas. Then this edge is filtered and further processed at subpixel level using cubic spline interpolation for curvature analysis. Then the point having curvature maxima irrespective of gradient direction is identified as anatomical landmark. This semi-automatic anatomical landmark extraction process based on image processing is coded in Matlab. This will help to quickly access the ethnic variation of Indian knee than the Caucasians. This method will also help to access any anatomical deformity in our musculo-skeletal system and in other systems through medical image data. This method also has been tested on x-ray data and produced a promising result.

9. Effect of mismatch of TKR : A finite element analysis (part of research work): 

The main objective of this work is to perform contact biomechanics analysis using Finite Element Methods (FEM) to study the mechanical effects on mismatch of Western Total Knee Replacement (TKR) components (i.e. Femoral component, Polyethylene component and Tibial component) while fitting in non-natives like Indians and contact stress-strain analysis between femoral component and Polyethylene (PE) components of TKR, as they play important role in success of TKR implants. We have generated a CAD model of one TKR and then observed improper fitment of that TKR (Total Knee Arthroplasty) while fitting to the Indians through computer simulation model,Following major challenges are faced:

• Reverse engineering for extracting CAD parameters from scanned image in terms of point cloud data of 3D scanning of actual TKR
• HEX Meshing of complicated CAD geometry
• contact biomechanics study at the joint during different loading conditions at different posture
  

10.Assessment of Thermal sensation response of Indians (part of research work):

Effects of ambient humidity, subjective thermal responses are being studied for Indians in their thermal sensation response while working in different occupational set-up, both by experimental (left-side figure on experimental set-up) and computer simulation study, CFD analysis.

11. CFD simulation on adaptive sweating response of Indians in indoor work environment (Part of research work):

The aim of this study is to provide a transient CFD solution for better comprehend the evaporative cooling process through human skin in 5 different simulations. skin geometry is represented as 10x10x1.3 mm cuboid (Figure 10a) which is placed inside a domain of 50 mm (L) x 30 mm (W) x 6.4 mm (H). With k-W SST turbulence model 2 simulations are done in absence of water a) only through dry heat exchange b) combination of dry and latent heat exchange and rest 3 methodologies considering sweat as c) water droplets d) water and Nacl solution droplet and e) a layer of water. In addition to evaporative cooling process, this study focuses on the following objectives: 1. Understand the distribution of thermal comfort parameters like air velocity and temperature in indoor spaces like a) inside car, b) inside office space and c) inside conference room; 2. Correctly modelling of sweat evaporation phenomenon. 3. Predict the local temperature gradient over the skin surface. 4. Calculate and compare different ways of modelling the sweat. 5. Model the mean age of air and CO2 Concentration to measure the freshness of air and safe regions. And lastly 6. Suggest suitable mechanical system for saving energy.

12.Biosensor design (part of project and research work):

A. Recording of Heart and lung sound:

As a part of this project, digitization of heart sound (.wav file) recording from a normal subject using our own circuit based on digital stethoscope using Audacity software as follows.

B. PPG signal acquiring for measuring HR & respiratory rate

Photoplethysmogram (PPG) signal is collected using an IR sensor where both the emitter diode and the detector are arranged side by side in a leaded package and a sample of recorded PPG signal is given below (Figure 19). Then using Wavelet decomposition, respiratory rate is calculated.

C. Electrogoniometer design & gait analysis

A new electrogoniometer is designed and developed. It is used to measure knee flexion-extension angle espiratory rate is calculated.

D. Working on IMU sensors and others

A research problem is to identify and examine the Restricted Repetitive Behaviors (RRBs) and balanced muscular tone and strength using different sensors like Inertial Measurement Units (IMU), flexicurve etc.. Different other analog and digital sensors are regularly used to collect different human parameters, to measure human response or in assistive device design. Microcontroller and Audrino are mainly used to collect and process the data in an isolated device.

13. Work on Automobile engineering and road environment(Part of research and Project work):

i) Automatic Robust Lane Detection

Currently, we are focusing on MATLAB code development on robust Lane detection (using camera output), which can work well under complex scenarios including shadow contamination, inhomogeneous lightening, partial/fully occluded lanes with dense traffic. Lane detection consists of online processing of capturing video/image of road lane marking, lane modelling, feature extraction, lane detection, lane tracking.

ii) Improved direct visibility and driver’s safety (Part of UAY project with Volvo Truck India)

In this project, to improve driver’s direct visibility, the dashboard and door design is modified and is being tested virtually in static condition. Another effort is being made to create Indian virtual road environment based on AR/VR technologies to study the driver’s behavior on driving simulator. In addition to this, another MATLAB code is written to simulate how truck driver will see the pedestrian or vulnerable road users (VRUs) through direct and indirect vision

14. Neuromotor Development Disorders in infants and children(Part of research and Project work):

The present screening method for neuromotor developmental delay and restrictions in infants worldwide is very much depending on parent’s report and doctor’s qualitative assessment based on expertise and attitude of the doctor. Effort is being made to assess infant’s stability and related balanced muscle tone, their theoretical construct, behavioral and social response, evoked response etc. related to neuromotor development status. As a part of project work, computer vision coding using PYTHON is written for online automatic eyeball identification and localization in different eye configuration from camera input with frame rate 30 frames/sec.