Real-Time Measurement ofPrehensile EMG signals.ppt

Real-Time Measurement of Prehensile EMG signals Master Thesis Saksit Siriprayoonsak Supervisor: Marko Vuskovic Department of Computer Science San Diego State University August 24, 2005 Contents Introduction EMG Overview Apparatus for EMG Measurement Implementation of EMG Capture Program Experimental Results Conclusion Multifunctional Prosthetic Hand Control Object of Thesis Main purpose: Design and develop hardware and software for measuring surface EMG signals from real human muscles in real-time. Immediate application: To control the existing SDSU multifingered robot hand. EMG Overview EMG – Electromyography Electromyography measures the electrical impulses of muscles at rest and during contraction. Amplitudes of EMG signal range between 0 to 10 mV (peak-to-peak) or 0 to 1.5 mV (rms). Frequency of EMG signal is between 0 to 500 Hz. The usable energy of EMG signal is dominant between 50-150 Hz. Amplification of EMG Signals Factors to be considered: Boost signal to TTL standard level (± 5 V.) Enough gain Noise/Artifact problem Filter, stability of electrodes attached to skin, proper grounding DC offset or bias problem Bias adjustment Power consumption Consume less current EMG Measurement Stages EMG Amplifier: Electrode and Extension Stereo phone wire with 3 conductors Positive input to preamplifier Negative input to preamplifier Shield as the input of body reference circuit Velcro strap for securing the electrode to the skin EMG Amplifier: Electrode and Extension (cont.) Plastic piece and snap on for holding electrode elements Dimension of 1 inch between electrode contacts 4 electrode extensions and 1 body reference extension Total of 9 electrode contacts EMG Amplifier: Power Supply Dual Supply Positive Power Supply Negative Power Supply Two 9-volt batteries connected in series Capacitors provide stability of electrical current. EMG Amplifier: Preamplifier Industry standard instrumentation amplifier op-amp (INA2128) Accuracy: providing high bandwidth a