Galileo Bionic Hand - ST Nucleo Example¶

This is an example of a simple hybrid sEMG(surface Electromyography) activated controller for the Galileo Bionic Hand Prosthesis implemented with the Galileo EMG Shield. The user has to select the desired posture by sending a special character through serial port (115200 baud rate) and then perform it through sEMG activation by detecting contraction on flexor muscles of the forearm. Contractions on forearm extensor muscles releases the posture and allows the return to the default or rest posture.

Special characters:

• '1', for "Power Grip" selection
• '2', for "Point" selection
• '3', for "Pinch Grip" selection
• '4', for "Lateral Grip" selection
• '5' for "Tripod Grip" selection

Galileo EMG Shield - 3 Channels for surface EMG¶

Electrodes Placement and Connection¶

Standard surface mounted Ag/AgCl electrodes with wet conductive gels are placed on palmaris longus and extensor digitorum muscles, focusing only on below elbow disarticulation. These electrodes have been well-characterized and most of its properties are well understood, except for some properties as drifting and low-frequency noise. Nevertheless, with proper preparation of the skin, the sEMG signal is excellent.

Disposable electrodes and snap leads information:

• http://bio-medical.com/products/din-ekgemgeeg-snap-leads-24-inch.html
• http://bio-medical.com/products/covidien-kendall-disposable-surface-emg-ecg-ekg-electrodes-1-24mm-50pkg.html

Proper placement of disposable electrodes for two channels of surface EMG is shown below:

Customizable Postures¶

You can customize the actions by modifying PWM values (microseconds) on FingerPosition function (values depends on the way that the hand was built it). The prosthesis has five fingers and a thumb rotation mechanism and five actuators in order to perform multiple types of grasping. Wrist rotation will be implement later.

The servo motors have to be connected as shown below:

Function Declaration and Usage Examples

void FingerPosition(float32_t thumb_us, float32_t index_us, float32_t middle_us, float32_t pinky_us, float32_t thumbrot_us);

FingerPosition(2400, 600, 600,2400,2400);   //Close
FingerPosition(2400,2400, 600,2400,2400);   //Point
FingerPosition(2400, 600,2400, 600,2400);   //Pinch
FingerPosition(2400, 600, 600,2400, 600);   //Lateral
FingerPosition(2400, 600, 600, 600,2400);   //Tripod
FingerPosition(1000,2400,2400, 600, 600);   //Open

Serial Oscilloscope Feature¶

This feature easily allows to watch and log to file the data using serial oscilloscope software (115200 baud rate).

• Serial_Osciloscope(TRUE,RAW) to watch raw signals, FALSE deactivate this feature
• Serial_Osciloscope(TRUE,RECTIFIED) to watch rectified signals, FALSE deactivate this feature
• Serial_Osciloscope(TRUE,SMOOTH) to watch smooth signals, FALSE deactivate this feature

Universal Real-Time Software Oscilloscope GUI information: http://www.oscilloscope-lib.com/

Nolia 5110 LCD¶

Nokia 5110 display implementation for visual feedback will be add later, we have to modify libraries and fonts in order to improve the functionality. The main idea is to change of action by pressing a push button and change thresholds using a potentiometer.

Information¶

Videos, bill of materials and tutorials to build the Galileo EMG Shield and the Galileo Bionic Hand will be posted soon, more information on:

• turing.galileo.edu/index.php/projects/galileo-hand
• http://bit.ly/arm_bionic_robo_hand
• http://bit.ly/galileo_hand_article