Prosthetic Hand Dola Ram,12263,Nit Hamirpur

Prosthetics Disease & amputations have been common throughout history People with visibly different abilities (i.e.“disabilities”) make up about 10% of population. Unjust barriers prevent equal participation –Lead to less productive society Prosthesis is an artificial device that replaces a missing body part.

Benefits of Prosthetics Prosthesis: artificial device that replaces a missing body part –Glass eye & myoelectric arm or leg Orthoses: augmented body parts –Glasses & knee brace Improved manipulation, mobility & sensing Psychological effects –Improved social interaction –Reduction in secondary effects due to isolation Reduction in healthcare costs –Chronic care facilities are very expensive –Aids to improve independence are less

Prosthetics: Mechanical + dynamic + Electrical New prosthetics use robotics technologies –Microelectronics & sensors –Electric & pneumatic motors –Control methods Understand human movement -Prosthetic hand interact with human user Very demanding applications –Batteries are heavy Design for low power –Demanding users want to go places and do things Design for harsh environments EMG Sensor Robot Hand

Prosthesis Development Process Identification of pathology or ablation –What function is missing? Identification of affordable technology –What motors and sensors? At what cost? Determine level of functional replacement –What is possible? –Keep it simple & effective! Risk evaluation –Never underestimate what can go wrong! –What is the acceptable risk level? Prototype device, test & start again Test on larger population set Manufacture & distribute device

Current Prosthetics Hands Cable-driven devices –Developed-world devices (Otto Bock Double-Cable Hand) Pneumatics (1960s s) –“Rocket” powered Vanderbilt arm (2006+) Utah Arm (1980s +) –Battery-powered arm Otto Bock C-Leg (2000 +) –Electric lower leg

Electromyography Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles Electromyography (EMG) is a suitable approach for human-machine interface in the prosthetic hands control. Electrical signal is generated by activation of muscle is detected. EMG signal measured by placing conductive elements or electrodes on the skin surface, or invasively within the muscle.

Muscle Physiology Muscles is composed of single cells or fibers embedded These fibers are excitable cells. Motor units control groups of muscle fibers Brain recruits motor units to innervate muscles for movement by sending electrical signal.

Acquisition of EMG As the brain's signal for contraction increases, it both recruits more motor units and increases the "firing frequency" of those units already recruited. When individual motor contract, they repetitively emit a short burst of electrical activity known as the motor unit action potential(MUAP). MUAP is detected by electrodes on the surface of the skin in proximity of the motor. EMG technology enables us to record the action potentials

Acquisition of EMG:CoNt Figure: Detection of the MUAP Figure 2: Action potential (AP) of one motor unit

Acquisition of EMG:CoNt EMG signal of greatest amplitude is detected by put the electrode at proper locations on the surface the muscle. EMG signal is random signal Bandwidth is Hz The physiological and biochemical characteristics of muscle influence the EMG signals

Electromyography Signals: Muscle Anatomy

EMG signal to control the Prosthetic Hand Figure: Control of the multifunction prosthetic hand using surface EMG signals

EMG SIGNAL PROCESSING After properly reading the myoelectric signal Applying high-pass and low-pass filters, converting it from an analog to digital form, stored it in memory. Signal processing -includes preprocessing of the raw data, feature extraction, dimensionality reduction, pattern recognition and finally online and offline learning.

EMG Signal Processing: System Flowchart

EMG Signal Processing: Onset of Movement Detection There are several threshold-based as well as statistical methods for detecting the onset of movement. Statistical methods generally perform better than their threshold-based. Lidierth (1986) Hodges & Bui (1996) Bonato et al. (1998)

Hodges algorithm W indicates the window size h represents the threshold in number of standard deviations. yk is the EMG signal

EMG Signal Processing: Bonato Method

EMG Signal Processing: Feature Extraction Methods Mean Absolute Value Mean Absolute Value Slope Willison Amplitude Zero Crossings Slope Sign Changes Waveform Length Simple Square-Integral Amplitude of the First Burst Multiple Time Windows Short-Time Fourier Transform Wavelet Transform Wavelet Packet Transform Spectral Moments

Classification: Methods Artificial Neural Networks (McCulloch-Pitts, 1943) ARTMAP Networks (Grossberg et al., 1976) Mahalanobis-Distance Based ARTMAP Network(Xu et al., 2003) Maximum Likelihood Estimation (Fisher, 1912) Mahalanobis Distance (Mahalanobis, 1936)

How does Myoelectric Work? Myoelectric relates to the electrical properties of muscles Electrode on skin Electrical field generated by activation of muscle is detected The strength of the field is roughly proportional to the activation level of the muscle –Above a certain level the muscle is “on” –Below it is “off” EMG Signal Muscle Off Muscle On

How Prosthetic hand is controlled? EMG signal processing identify the type of grasp The capability of controlling the prosthetic hand is embedded in the chip Microprocessors controls the movement of the finger s and force applied by the fingers. So these type of technical solution lead the amputees and person with different abilities to do everyday task effectivily.

Research: Online Learning Real-Time program should be written in multi-threading capable language Online learning capability with feedback from prosthetic hand Distance based network suggested

END Electro mechanics attached to body bridge the gap between disability and ability, between human limitation and human potential. Thank You