Project MARCH VIII

Project MARCH is a student team, a so-called Dream Team, of the Technical University Delft. Every year a group of 28 enthusiastic and motivated students put their study on hold for a year to fully commit themselves on designing, developing, and building an exoskeleton. An exoskeleton is a robotic motorised suit that enables someone with a complete spinal cord injury, who is wheelchair-bound, to stand up and walk again. We design this year’s exoskeleton together with our 29^th and most important team member: our pilot Koen van Zeeland. Koen has a complete spinal cord injury and has been working with Project MARCH for 3 years now.

The vision of Project MARCH is that technology can improve the quality of life for people with spinal cord injuries. We want to accomplish this by designing a better exoskeleton each year. Last few years Project MARCH focused on dynamic walking, which means that the exoskeleton is more adaptable to daily life. The exoskeleton is now able to see its surrounding and react to it by stepping on the right spots and giving suggestions to the pilot. This year we are the eighth team, and we want to focus on balance. The last few years crutches were used by our pilot to balance himself or herself in the exoskeleton. This year’s goal is to not use the crutches anymore. This means the user of our exoskeleton has his hands free which makes the use of the exoskeleton more user friendly.

Electrical Goals

As balance is this year’s goal, the electrical system of the exoskeleton had to be improved. One of the main challenges was reliability. Each year we need a significant amount of training time with our pilot. Balance is something we cannot do on our own. The pilot has a huge impact on the system. Thus, our pilot must train a lot with the exoskeleton. In previous years the training time has always been somewhat limited as a lot of things broke down over time. Replacing, repairing, and debugging can take a lot of time. This is why we wanted to cut down on these replacing and repairing times by making the PCBs in the exoskeleton a lot more reliable.

Another major goal for the electrical department was adding support for torque sensors and pressure soles. The high-level control of the exoskeleton has been changed a lot to achieve balance. One of the major differences is the switch from position control to torque control. For us to be able to do this we need a torque estimation. We have decided to add torque sensors in all the joints, and for us that means we must add support for the sensors onto the PCBs. Another sensor which has been heavily researched by previous MARCH years but has never been included in the final exoskeleton is the pressure sole. This is a force sensor which is placed in the sole of the foot. This sensor can measure the force different parts of the foot exercise on the ground. This year we finally have an implementation integrated into our PCBs.

DieBo

If you were to compare the exoskeleton to a human, the central nervous system is connected using EtherCAT. Our inhouse designed DieBo is part of this nervous system as a general EtherCAT slave. It is the communication shield of our motor controller which handles communication between our sensors, joints, and computer. The DieBo design of MARCH VIII has been improved to include support for the new sensors mentioned earlier. Its power distribution has been simplified to be more reliable and the connecter placement has been changed for better cable management compared to last year.

Since the start of our year, we’ve worked extensively. Our digital design for the new exoskeleton, the MARCH VIII is finally ready! Now that the digital design is done, we will start producing the physical components. Our Electrical Engineers receive valuable help from Eurocircuits in terms of producing our PCBs. Curious to see how it turned out?