Let It Flow

As readers of Hackster News are well aware, the past decade has seen an explosion of new platforms that aim to make electronics and computing more accessible to hobbyists and prototypers. Arduino and Raspberry Pi, for example, have opened up a whole new world of low cost, simple to use, embedded device development platforms. And with tools such as these rising in popularity, a number of supporting platforms have also started to appear. For example, if you want to make your creations move, the Soft Robotics Toolkit, Pneuduino, Programmable Air, and FlowIO offer modular options for building gas-based actuation mechanisms. This has been a big boon for developments in soft robotics, but development platforms focused on simplicity of use in hydraulic actuation have not yet been given much attention.

Hydraulic actuation development kits are finally starting to get the attention they deserve thanks to the work of a team lead by engineers at The University of Tokyo. They have designed a system called HydroMod, which is a set of modules that make it simple to construct prototypes of hydraulic-powered devices. With the palm-sized modules of HydroMod, liquid flow can be generated by simply connecting the various modules. The path of that flow can be configured by combining the modules into the desired pattern.

It is no accident that few hydraulic toolkits have thus far been made available — there are significant challenges to overcome in creating them. They typically require large, external devices like pumps, tanks, and valves to generate liquid flow, which makes the systems cumbersome and expensive. Further, hydraulic systems are difficult to reconfigure once the path of liquid flow has been established. This makes a general purpose toolkit very challenging to create. Finally, if any part of the system develops a leak, the entire system will be compromised and cease to function properly.

The novel approach behind HydroMod seeks to address all three of these difficulties faced by present systems. Rather than using bulky traditional pumps, the team made use of electrohydrodynamic (EHD) pumps. EHD pumps are simple and require no mechanical moving parts — an electrode is placed into a dielectric liquid (Novec 7100), and by applying a voltage, flow is generated. The modular nature of HydroMod addresses the final two difficulties. By rearranging modules, the flow path of the liquid can be changed at any time. Further, if a leak does occur it will be isolated to a particular module. By swapping out that single module, the entire system can be put back in good order.

The system is composed of three types of modules. Pump modules are designed to generate liquid flows, while Actuate modules supply the high voltage that drives the Pump modules. Wire modules are used to connect the other modules together, and give the actuation system its desired liquid flow path. Modules attach to one another via magnetic attraction, and the magnets also act as conductors to extend the circuit between modules. The actuation can be controlled via a smartphone app that interfaces with a 2.4 GHz radio (nRF24L01+) on the Actuate module. This module also contains a ATmega328P-AU microcontroller that can be programmed with the Arduino IDE.

The team is currently working to allow the direction of liquid flow to be reversed programmatically; as it presently stands, the Pump module needs to be physically installed in the opposite direction to reverse flow. They are also working to add further functionality to the programming environment, which is limited to changing voltage levels and selecting synchronous fluid patterns. We hope to see this work continue to lower the barriers to entry for prototyping with hydraulic actuators.