Hi, my name is David. I’m an electrical engineer at Project MARCH. This is a student team from the Delft University of Technology. With 31 students we’ve built an exoskeleton, the MARCH II. An exoskeleton is a robotic suit that helps people with a spinal cord injury to walk again. In the image below you can see Ruben walking in the exoskeleton. Ruben has a spinal cord injury and is our pilot of the exoskeleton.

DavidK.png

Together with Ruben, we compete at the Cybathlon Experience. This is a spin-off of the Cybathlon, a competition for para-athletes with bionic resources.

During the Cybathlon Experience we will face an obstacle course with imitates daily-life obstacles for wheelchair users, such as the stairs and a ramp.

In the past year of Project MARCH, weve designed three different PCBs ourselves, which were produced by Eurocircuits.

The first one is the Power Distribution Board (PDB), it is located in the backpack of the exoskeleton. The PDB has a 48V connection from the battery and divides it in high power (48V) for the motors and low power (12V) for electronics.

It also has several sensors to measure current, voltage and temperature which ensure safe operation when the exoskeleton is used by Ruben, our pilot. Further- more, the PDB is able to communicate via EtherCAT, the communication protocol we use in our exoskeleton.

This brings us to the next PCB, the General EtherCAT Slave (GES).

The General EtherCAT Slave is a multifunctional device. In the MARCH II we use four slaves. There is one slave on both legs, one in the backpack and one in the crutch. It also has EtherCAT communication and it has a programmable MBed microprocessor. It has several GPIO pins, used for different applications.

In the legs, we have attached a button, which is used to climb the stairs, which is one of the obstacles of our competition. The GES also reads out the temperature of the motors. The GES in crutch controls the input device. The input device consists of a screen and two buttons implemented in the crutch handle and is the controller of the exoskeleton. Moreover, the GES is used for audio feedback to the pilot as well as pilot positioning by means of an IMU.

The last PCB is the CBOB. This little board converts a single ended signal to a differential signal and the other way around. This is used to improve encoder signal integrity by making the signal less sensitive to EMI of the motors, which are placed incredibly close to the encoders.

We would like to thank Eurocircuits for making it possible to produce these PCBs which form the heart of the MARCH II electrical system.