This document discusses sensing and processing of bio-metric signals for use in low cost bio-robotic systems. It describes how bio-metrics work using input sensors, a processing unit, and an output interface. Bio-robotic systems are needed to replace humans in hazardous conditions and perform high precision tasks. Prosthetics are discussed as a type of bio-robotic system that can replace injured body parts either passively or actively using sensors. Electromyography and electroencephalography are described as sensing technologies that can be used in prosthetics. The document concludes that electromyography offers an effective low-cost solution for prosthetics, though customization is needed and signal strength depends on variable user factors.

1. Sensing and Processing of Bio-metric Signals
for use in Low Cost Bio-robotic Systems

2. What is Bio-Metrics?
 Biometry − Bio (Greek word for Life)+ Metrics (Measurements)
 Biometrics is the science of measuring and analyzing biological
data.
 Biometrics refers to technologies that measure and analyze
human body characteristics such as DNA, fingerprints, eye
retinas and irises, voice patterns, facial patterns and hand
measurements.

3. How Bio-Metrics work?

4. • Input Interface (Sensors)- It is the sensing
component of a biometrics system that converts human
biological data into digital form.
• Processing Unit- microprocessor, Digital Signal Processor
(DSP), or computer that processes the data captured from the
sensors.
• Database Store- The database stores the enrolled
sample.
• Output Interface- The output interface communicates
the decision of the biometric system to perform a task.

6. Need for Bio-Robotic Systems?
• To replace Humans in Hazardous Working
Conditions.
• Recovery of Human Organ Functions.
• To perform high Precision tasks ,such as
Surgeries.
• As Exoskeletons for paralyzed people.

9. Prosthetics
• Prosthetics are artificial devices that replace
injured or diseased body parts
• There are two types of Prosthetics-
1. Passive Prosthetics
2. Active Prosthetics

10. Requirements of a good Prosthetic
• Should match the real Limb as close as
possible
• Same Size as the Limb
• Low Weight
• Economical
• Long Lasting

11. Existing Prosthetics
1. Passive Prosthetics: They do not have sensors
or any control mechanisms. They are cheap.
2. Active Prosthetics: They use sensors and
Control mechanisms to mimic the actions of
the real limb. They are far more expensive
than Passive Prosthetics.

12. Sensing Technologies
1. Electromyography(EMG):
 Electromyography (EMG) is a technique for evaluating and
recording the electrical activity produced by skeletal muscles.
 An EMG signal is the electrical activity of a muscle’s motor units
 Most commonly used control method for Bio robotic systems
(Prosthetics)
 EMG frequency spectrum falls in the 0-500Hz range

14. 2. Electroencephalography(EEG):
 An electroencephalogram (EEG) is a technique used to track
and record electrical activity of the brain.
 EEG measures voltage fluctuations resulting from ionic current
within the neurons of the brain.

16. Invasive Vs Non-Invasive
1. Invasive –
 Requires Surgery or Implantation
 Risk of Infection or Electrode rejection
 High resolution of the obtained Signals
 More Expensive
 Used in special cases
2. Non-Invasive-
 Doesn’t require Surgery or Implantation
 Low resolution of the obtained Signals
 Less Expensive
 Commonly used

17. Choice of Sensing Technology
Advantages of EMG:
• Low cost
• Simplicity: Most times, surface electrodes are
sufficient to collect adequate data.
• Prediction: In most muscles, the EMG activity
precedes the motion of the actuated limb.

18. Circuit Design
• Sensing Circuit Comprises of 3 stages
1. Input Amplification
2. Filtering
3. MAV(Mean Average Voltage) Circuit

20. Input stage
• Consists of Sensory Circuits
• Sensory Circuits comprises of a set of Silver
Chloride Electrodes attached to person’s skin
• One electrode is placed at core of the target
muscle
• Other electrode is placed at a remote location
• An instrumentation amplifier is used to
amplify signal by x1000

22. Filtering Stage
• Filtering stage consists of High Pass and a Low
Pass Filter
• More Dominant frequencies are identified
after Fourier analysis and rest are filtered out
• Frequencies 20Hz to 400 Hz are allowed to
pass

25. MAV Circuit
• MAV (Mean Average value) circuit consists of
1. Peak Detector
2. Clipping Circuit
3. Integrator
• Peak detector converts signal to a series of
Peak spikes
• Then Peak values are cut off at a safe Voltage
level

26. • Integrator provides a slow signal that rise and
fall with the amount of muscles activity.

27. Conclusion
• Prosthetics based on EMG offers an effective
low cost solution for amputees.
• Prosthetics based on EMG have the following
disadvantages:
1. Injuries are not same for every amputee, so
Prosthetics have to be customized.
2. EMG signal strength depends on many factors,
such as Muscle size ,Skin type etc, some of which
may vary with time.

32. THANK
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