2016 M2x MDH
2016 W2x POL
2016 M8+ St.Paul
2016 LM4- DEN
2016 W8+ Cornell

New BioRow developments

New BioRow developments

A new BioRow® 2D force sensor for a foot-stretcher was recently developed, which can be used with our erg system (RBN 2017/05), as well as in the boat. Force is a vector, which means its direction is as equally important as the magnitude. Horizontal and vertical components of stretcher force play very different roles in rowing biomechanics, so it is important to measure them separately, not just “stretcher force” without reference to its direction (RBN 2015/02). 

Each new sensor weighs only 80g, so the system with four sensors (toes-heels, left-right) with an additional foot-plate would add about 0.5kg of extra weight to the boat and will increase the thickness of the foot-board by 2cm (Fig.1,a). Each sensor measures two force components: horizontal and in vertical, so the whole system requires eight input channels.

 

With purposes of verification and correlation with previous measurements, the new sensor was installed on top of our previous stretcher sensor, which measures perpendicular (normal) to the foot-plate force at the same time. Normal components of the horizontal Fh and vertical forces Fv were derived, summed up for both heel and toes sensors separately and compared with directly measured normal forces Fn (Fig.1,b). A good correlation of forces was found, which proves the new sensor is able measure force components reliably.

 

Fig 2 shows a data sample collected at 32spm on Concept2 rowing machine equipped with both types of the stretcher force sensors. It is interesting, that at the catch, the horizontal force was applied mainly through the toes (a), but the vertical force was applied through the heels (b). During the second half of the drive, the horizontal heels force achieves about a 40%  similar peak force at toes (c), then, the last point became negative (d), when the rower pulls the stretcher through the toes. 

The new stretcher force sensor could be used as an instrument for in-depth research studies of rowing biomechanics.

We are working on connection of BioRowTel system to NK EmPower instrumented oarlocks (1). Theoretically, the ‘Master’ unit of the BioRow® system should be able to connect wirelessly with up to eight oarlocks, though at this time, only a connection with four oarlocks was successfully tested. Once fully developed, it will be to possible receive per-stroke data from the connected oarlocks (the same data available upon connection to the NK Speed Coach), and also real-time data, like the “force-curve”. Information from the oarlocks could be recorded in the Master unit together with other data: the boat speed measured using GPS or impeller, 3D boat accelerations and rotations (roll, pitch and yaw, RBN 2012/03), and up to 12 channels of analogue data, which can be used to measure seat and trunk movement, so Catch, Rowing Style and Finish Factors could be derived (RBN 2015/09-11, 2017/06). Many other biomechanical variables could be measured using BioRow® sensors (2), which will greatly expand the capabilities of our system for rowing technique analysis.

 

We are also developing real-time viewing so the data collected by the Master unit could be transmitted wirelessly through Wi-Fi to a tablet computer (up to 100m away), where a coach can see synchronised force curves, power output of each crew member and other biomechanical values (stroke length, average forces, “slip” and “wash”, etc.). With systems installed on more than one boat, Wi-Fi could automatically switch from one to another. Follow our website for more information on progress of these developments.

References.

1. NK Empower instrumented oarlock. http://www.nkhome.com/rowing-sports/empower-oarlock 

2. BioRow instrumentation. http://biorow.com/products/biorow%20instumentation/