Introduction

Introduction

Welcome to the the weblog for the Soft Robotics AP Project for 2017. We hope you’re as excited to read this weblog as we were when we took the first tentative steps into the world of soft robotics. We were fortunate that our team consisted of academically and culturally diverse people from various places across the globe. Let’s meet the group…

The Team

Peter Taylor

Loughborough University United Kingdom

Industrial Design and Technology

Melvin Costa

TU Delft
Netherlands

Aerospace
Engineering

Robbie de Groot

TU Delft
Netherlands

Industrial Design
Engineering

To provide guidance, counsel and experience, we were assigned two resident experts…

MSc. Rob Scharff

TU Delft
Netherlands

Design
Engineering

Bas Smit

TU Delft
Netherlands

Design
Engineering

The Task

It’s safe to say when we started this, we had never heard of this field of work before and we were all excited to get started. We were quickly briefed on the main expected goal for this project…

Create a fully autonomous walking robot using ‘soft’ technology.

A daunting task, especially to us – the uninitiated. Things became clearer as various features were explained and the technologies that Rob and Bas have developed, demonstrated. A plan was drawn up of the weekly goals we should be striving for…

  • Week One:
    • Test/calibrate micropump
    • Background research into locomotion
    • Print existing actuator

     

  • Week Two:
    • First working prototype to prove concepts for the mid term presentation
    • Have as much to show as possible

     

  • Week Three:
    • Working towards final protoype

     

  • Week Four:
    • Prepare and present work at the science fair

We were definitely expecting this list to expand as we became more familiar with the project and the kind of work we would be doing. At the start we were still very unaware as to the extent of the project and how much time and effort it would take to achieve the goals so for us. It wouldn’t be until we got stuck into the more in depth discussion and planning over the first few days that we became fully aware of the man hours needed to get a robot walking.

The Tech

So just what is all this technology that’s being mentioned? Well ponder no longer as we take a look at the main components that we used throughout our project…

Bellows

The bellows, designed by Rob, are 3D printed and use varying degrees of flexible and rigid material to achieve actuation. Air is pumped into the aperture and due to there being more flexible material coiled up across the top of the bellows, compared to the shorter, rigid material across the bottom, the bellows create a curling motion. It’s this motion that we need to harness to get a robot walking.

Valves & SMAs

The valves, designed by Bas, are also 3D printed but only use the most rigid and flexible materials. There are two valves in this design. The left valve controls the outflow of air so that the bellows can deflate and the right valve controls the air intake. The parts that push against the black flexible tubes are controlled using a spring to exert pressure, closing the tube and shape memory alloy wires (SMAs). When current is ran through the SMAs, the wire contracts with a lot of force, pulling the spring and opening up airflow. When the SMAs cool, the spring takes over and closes the tube back up again. By controlling the current and the time it is flowing through the wire, we should be able to easily control the valves.

Micro Air Pump

The micro pump we were given works at around 3V and uses a small motor connected to a diaphragm to extract the required air from the atmosphere. While achieving the job of inflating the bellows, it inflates one quite slowly, so if we were splitting the pressure between multiple bellows the process, which would be easier to control, would be a little too slow for our liking. Because of this we purchased a new, 12V pump that provides a lot more pressure and inflates the bellows a lot faster. This is great as it speeds up the walking gait cycle, looks more impressive and can simply be powered using a 9V battery, which enough for our purpose.

Arduino Uno, MOSFETs & Batteries

Effectively the brain and power for the robot. The arduino uno will allow us to control the actuation of the bellows quickly and with precision, as well as being able to control the pump. The Grove MOSFETs (Metal-Oxide Semiconductor Field-Effect Transistor) have a complex name but simply allow us to be able to control separate components using different power supplies as the arduino works using 5V and so any components, such as the 12V pump, won’t work very well being powered straight from the uno. High voltage components such as these can often drain the power from the arduino making it act in a sporadic manner.