Servo Shoulder Support (Partial Exoskeleton)

My father is over 80 years old and has a damaged shoulder which he does not want to have operated on. He can no longer lift his arm very high.

We have tried various exoskeletons for craftspeople, but the devices all bring the same problem: people with disabilities can't put them on themselves!

I would therefore like to make my servo support for my father's shoulder. The control unit I have already posted here. This controller is on the wrist, a XIAO nRF sense registers the hand movements and converts them into signals for the servo. But see here how the shoulder support is done:

Basic experience with the Arduino IDE is required.

material servo unit:

1. 3D printed parts
2. 40kg servo
3. ball bearing
4. several screws

material controller:

1. ESP32
2. buck converter 18V --> 7.4 V
3. buck converter 7.4V --> 5V
4. switch
5. capacitor
6. 18V battery for gardening tools (here: Gardena)
7. [alternatively a 7.4V Lipo with enough amperes]
8. plastic stripe 3mm

The Shoulder Helper consists mainly of a support arm reinforced with a servo.

The requirement is all 3D parts. I printed them with PLA and a 15% infill structure, which is stable enough.

1. The servo is inserted into the housing and later fixed with hot glue.
2. One end of the servo axis is fixed with a ball bearing.
3. Screws connect the other end to the servo arm.

A hairdryer is required to bend the neck support accordingly.

This device only requires a single servo to lift the arm. Lateral movements of the patient's arm are still possible under their own power. The hinge behind the servo makes this possible. The hinge should be positioned as directly as possible above the shoulder joint.

You can find out how to make the remote control here in this project.

The identification number in the program for the BLE contact is already coordinated in both projects.

The receiver unit or control unit for the servo is an ESP32 microcontroller. It is also set up for BLE, pairs with the wrist control unit after switching on and processes its signals.

The ESP32 runs with 5V. I used a stronger battery so that the servo develops enough power. That's why the ESP32 needs an upstream 5V converter. But more on this in the next step.

So that the device has enough power and my father doesn't have to use smaller 3.7V batteries, I use a battery pack (Bosch) from a Gardena gardening tool. Its 18 volts must first be brought up to 7.4V, which is compatible with the servo, using an adjustable buck converter. An intermediate capacitor prevents current fluctuations and trembling in the servo.

Although the battery is large, it is easy to grip and only needs to be pushed into the holder, where the copper strips ensure contact.

A second converter is used for the ESP32, which provides 5V for the microcontroller.

The battery holder and control unit are located on a mounting plate, which is fitted with a belt clip.

The servo housing is screwed to the hinge, to which the shoulder rest and neck rest are attached. A hairdryer is required to bend the neck support accordingly.

1. Battery/control unit on the belt.
2. Attach the shoulder section.
3. Close the Velcro strap around the upper arm.
4. Switch on the control unit.
5. Switch on the wrist control. (LED blue on successful start, green on contact with shoulder support).