Meet the Electrical Engineers of Project MARCH – Tristan Wieffering

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Hey there! In previous posts members of our team who did their Bachelors at EEMCS have been introduced. Today, I will tell you a little bit about what we are actually doing as students from this faculty. But first: a quick reminder of who we are and what we do!

We are a team of students, spending a year building an exoskeleton for people with a spinal cord injury. We are striving to give back full mobility to paraplegics, such that they can participate in their daily life activities in a natural way. Our pilot will be using the exoskeleton we are building this academic year, to race against other people using exoskeletons in the so called Cybathlon, a competition for bionic athletes.

But what do we need from an Electrical perspective to build such an exoskeleton? First of all, we are going to need something to supply us the energy. A battery is, given our application (a wearable machine), the most suitable choice. If we start at the battery and we want to end up with a moving – purely mechanical – joint we are going the need a few pieces of electronics. Because we are using a (brushless) drone engine we need a special module to get the motor spinning. This module is called a servo driver and sends the right signals to the coils inside the motor. For this the servo driver needs some additional timing information, which we get by adding certain sensors that can measure the rotational angle of the motors. Interesting with these sensors is that setting them up takes great care. They have to be aligned very carefully at distances much less than a millimeter. Furthermore, to be able to reliably receive the data these sensors transmit in the noisy environment that is created by the powerful and fast changing signals everywhere in the exoskeleton, we'll need some additional things (like shielding and/or differential signaling).

Now that we can rotate the motors, we are going to connect the servo drivers to the battery via a piece of electronics that implements certain protection measurements (over-current and over-voltage) and allows monitoring the energy flows: the Power Distribution Board.

Apart from this chain of electronics to get the motor spinning, we need some additional hardware: sensors to monitor things locally (such as the temperature of the motors, to be absolutely sure they don't overheat) and lastly a computer to control all of this.

Speaking of control brings me to the final piece of the puzzle. The control of the exoskeleton by its user! We will need a way for the user to translate its intentions to actual actions of the exoskeleton.

Alright, now you know what electronics we need to build an exoskeleton, you also know what we are doing this year. We custom design the Power Distribution Board, an additional Printed Circuit Board (PCB) and our own sensors for the servo drivers, get the motors spinning by programming the servo drivers, get the computer to control everything, interface with sensors, build the hardware for the user to control the exoskeleton, design the battery and do cabling!

Thanks for reading! To stay up to date about our project, check out our website at projectmarch.nl or our social media!

RB & MAG