Positioning of Solenoids and Dampening Actuators to Maximise Tonal Range

This post is directed to Bodhrán players so the first paragraph is a quick recap on what this project is about.

We are looking for some help and advice on a project we are currently working on. The goal of this project is to enable a young man with a physical disability play the Bodhrán and ultimately accompany a group of traditional musicians. We hope to achieve by supplementing his own assistive technology (Windows based computer with eyegaze input) with a range of open source (where possible) hardware and software that will allow him both compose beats and control various parameters of the playback in real time using his eyes. The physical playing of the Bodhrán will be achieved using a range of solenoids and actuators controlled by a microprocessor. If this project can be realised within the time-frame we propose having its inaugural performance on International Day of People with Disability whose theme this year is Sustainable Development: The Promise of Technology. (continue reading original proposal here.)

Firstly I want to assure you all that we are not planning to replace all bodhrán players with robots and we fully realise that our approach couldn’t hope to achieve the nuanced sound of a bodhrán in the hands of a skilled musician. With your help however we can give the opportunity of playing this wonderful instrument to some people who wouldn’t have the ability to play it in its traditional form and hopefully put a few smiles on faces.The gif below illustrates our approach. We realise this is not ideal for a number of reasons. The stroke action associated with playing a bodhrán isn’t possible to achieve with this setup. That is something we hope to work on for future iterations but in the meantime we thought by angling the solenoids we could at least go some way to approximating it. We also will not be able to achieve the range of tones or the smooth movement between tones that a hand would but we were hoping it would be good enough for some simple jig and reel rhythms with only 3 or 4 different tones.

Click on the picture below to see the full size animation.

animated gif illustrating how the 3 solenoids hit the face of the bodhrán and the actuators change the tone

As bodhrán players we were hoping you could advise us on positioning the solenoids which will strike the drum skin and the actuators which dampen the resonance and change the tone . We currently have three solenoids but the finished drum will have 5. Using the co-ordinates on the diagram below could you suggest where we should position the 2 most important (as we will be reserving one for hitting the rim). Then suggest the best places for the additional 2 (in case the other 2 don’t arrive in time and we have to get by with only 2).

circle divided into 46 numbered sections to represent positions on a bodhrán
This diagram can represent the front or the back of the bodhrán.

To control the tone and resonance we have two Universal Power Door lock Actuators and one heavy duty solenoid (5.5KG force). We are not sure whether we will be able to use the solenoid but the door lock actuators are perfect. We will put some kind of rubber ends on the actuators to attempt to simulate the bodhrán players hand. This will allow us regulate pressure and contact. In the diagram below I have suggested three possible shapes/types (A,B,C) for the ends of the actuators that will come into contact with the drum skin. Using the coordinate diagram above could you suggest the best place to position the most appropriately shaped damper (tone modulator). As the player will not be able to move these as a bodhrán player would the most common/useful position is what we are looking for.

diagram showing 3 possible types of dampers
In the diagram above imagine A as being something like pipe insulation, B a small soft rubber ball and C a larger rubber ball.

Some more details. Our initial aim is to be able to produce 4 tones (low, medium, high and the rim shot) but we are looking for the positioning that will give us the maximum tonal range possible. We are using a Waltons 16” Tunable Bodhrán. Solenoids can work at considerable speed, each solenoid could achieve in excess of 5 hits a second (this is an estimate).

Any help or ideas would be greatly appreciated.