In this manual you will find all the resources to design the various components of the MyoCoach.
To design the MyoCoach, you will need :
- A 3D printer
- PLA type filament
- An Arduino UNO type board link
- A female pin header strip link
- A male pin header strip link
- A set of electronic cables link
- Self-tapping screws 8 x ∅2.2-L5 link
- A strap with velcro and buckle link
Tools :
- A Phillips screwdriver
- A soldering iron + soldering accessories
- A tube of glue type Glue
The armband is the component of the MyoCoach that holds the two Ottobock EMG sensors (Ref 13E202) on the residual limb of the future prosthesis user. This armband is comfortable, inexpensive and facilitates the positioning of the sensors for the ortho-prosthetist.
The supports have been made with Fusion360 software.
The file in .STL format is available in src/hardware/casing
Prepare the different elements: the printed material, the strap and the EMG sensor.
- 1️⃣ Insert the strap into the side openings of the media.
💡 The strap must be forced in.
- 2️⃣ Insert the Ottobock 13E202 sensor into the holder, taking care to force the strap between the holder and the sensor.
💡 The sensor must go at the end of the mechanical stop in the holder.
The design of the sensor holder and especially the design of the slot where the cable passes through offers a certain freedom of positioning between the two sensors. This freedom of movement allows the two EMG sensors to be correctly positioned above the user's muscle areas.
The MyoCoach's case allows EMG sensor data to be acquired with an Arduino card and transferred to a computer for visualisation. It also allows the Ottobock electrode connector format to be adapted to the MyoCoach casing.
The casing of the Arduino Board has been made with Fusion360 software.
STL format files are available in src/hardware/casing
The main idea is to solder two female connectors (5-pin female pin header strips) to adapt to the female connectors of the Ottobock 13E202 sensors. The connectors are connected to the analogue ports A0 (EMG 0) and A1 (EMG 1) of the Arduino board.
The wiring diagram is as follows:
The result is as follows:
Prepare the following items: the Arduino card, the two parts of the case, the female pin header strips and the 8 self-tapping screws.
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1️⃣ Insert the Arduino card into the case.
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2️⃣ Screw in the 4 self-tapping screws to hold the Arduino card in the case.
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3️⃣ Using pliers, cut off the 2 outer pins of the snap-off strips.
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4️⃣ To hold the connectors in place in the box, apply 2 drops of glue (Glue type) before placing the connectors in the box.
💡 The cables are not shown in these illustrations but at this stage the connectors must be soldered.
- 5️⃣ Close the housing
⚠️ Before closing the case, the connectors must be connected to the Arduino board (+5v, GND, EMG0 → A0, EMG1 → A1).
- 6️⃣ Turn the MyoCoach housing over and screw in the 4 self-tapping screws to hold the two housing covers in place.
The connector of the Ottobock 13E202 electrodes is very specific.
But a simple 3-pin header strip is used to interface between the electrodes and the connectors of the MyoCoach box.
