Exoskeleton Arm Brace controlled by Automated (EMG) Mode and Joystick Mode
In automated mode, the user’s bicep and tricep muscles control the direction of the exoskeleton arm brace. The benefit of this, is that the user will not have to rely on the joystick device to tell which direction the arm is moving. However, due to potential problems and to avoid disastrous situations, the joystick mode was also implemented. Therefore, when the button “Z” is pressed on the joystick device, the mode will change depending on the user’s preference.
After being able to successfully control the exoskeleton arm brace with EMG signals, a strength test was performed in the automated mode. The different strength tests are shown below.
Automated (EMG) Strength Test (0-3.63Kg) with Exoskeleton Arm Brace
Automated (EMG) Strength Test (2.23Kg) with Exoskeleton Arm Brace
Automated (EMG) Strength Test (3.63Kg) with Exoskeleton Arm Brace
The results showed that the arm was able to withstand the arm’s weight, with an additional 3.63Kg. The potential problems that could arise from wearing this device, is that when the arm is going down in automated (EMG) mode, a small amount of force against the exoskeleton brace is necessary for the device to understand the correct direction.
These videos were made as we were integrating our current system(controlled manually with the joystick) and the EMG circuit. The user(Rahul) was asked if the exoskeleton was supporting his arm because the exoskeleton should keep the arm in place if the amplitude of the EMG signal is below the set threshold (relatively relaxed), to which he answered yes. The initial movement before the exoskeleton kicks in is due to the fact that the steel wires were not properly tensioned(a little loose) and there was room for the arm to move, which shouldn’t happen. The idea is that the arm should be held in place unless the servo rotates. We are currently in the process of tweaking the system to get desired and more consistent results.
3 comments
I don’t understand “small amount of resistance”.
Author
I updated the post to be more clear.
“The potential problems that could arise from wearing this device, is that when the arm is going down in automated (EMG) mode, a small amount of force against the exoskeleton brace is necessary for the device to understand the correct direction.”
In automated (EMG) mode, occasionally, the tricep signals do not give the correct amplitude (possibly because of the placement of the sEMG electrodes). This as a result, sometimes requires slightly more force against the exoskeleton brace when going down for the microcontroller to understand that the user is moving the arm downwards. This tends to happen when the user is picking up a heavy object, this rarely occurs when the user is not holding any other weights.
While I understand what the project is doing, it is hard to believe that the person is not just moving the arm up and down with their own muscles. You should think if a clever way to show what is really going on (maybe one person controlling the muscles while the other one wears the exoarm?) Maybe putting the exoarm on a mannequin arm (I know, hard to find – maybe talk to the Nursing dept)? Maybe stage one person asleep, who is wearing the arm, and a second person controls the arm of the first one. Not sure here. You should brainstorm. Here’s one company’s way of showing their human-human electronics: https://backyardbrains.com/products/HHI