ErgoArmMeter – A novel iOS application for measuring arm inclination

ErgoArmMeter is a professional inclinometer application for measuring arm elevation during work. It is developed by Liyun Yang (KTH Royal Institute of Technology) under the supervison of Mikael Forsman (Karolinska Institutet). This project is a collaboration between Institute of Environmental Medicine at Karolinska Institutet (KI) and School of Technology and Health at KTH Royal Institute of Technology (KTH).

It is shown by research that work with elevated arm may lead to shoulder/neck disorders. Ergonomists have been using inclinometers to measure arm elevation, which have a better precision than self-reports and observational methods. ErgoArmMeter is validated in an optical motion lab at KI and it has shown similar accuracy compared to other former validated inclinometers.

The validation experiment in the optical motion lab. A: Placement of two reflective markers and the iPhone with armband on right arm. B: Arm flexion posture. C: Painting on a straight board.

Upper arm inclination measurement during arm flexion. From the static experiment (B in the previous figure).

The validation experiments showed a high level of agreement between the two systems. In the static experiment (B, in the experiment-figure), the mean absolute difference between the optical system’s angles and those of the app was 1.5°.

In ergonomics practice, ErgoArmMeter would serve as a good alternative to other validated accelerometers. It has the advantage of low cost, easiness for use and directly obtained results. Also, due to the signal combination of the embedded gyroscope with accelerometer in the iPhone, it largely reduces the errors from the acceleration during fast movements. It can be used for evaluating the differences in arm inclinations between, e.g. two workstations, or before and after interventions. It can also be used for educational purpose. Together with other information about certain work task, it can add valuable information for risk assessments of the work task.

ErgoArmMeter is now available to download for free from the App Store, with the approval of Karolinska Insititutet Apple Developer Team. The user interfaces and functions will be further improved based on feedback from version 1.0.

User manual

User manual for ErgoArmMeter (English)

Användarmanual för ErgoArmMeter (Svenska)

Related articles & reports

Yang, L. and Forsman, M., 2015. Development and validation of a novel iOS application for measuring arm inclination. Abstracts NES 2015. Lillehammer, Norway: Nordic Ergonomics Society.

Yang, L., 2015. Development and validation of a novel iOS application for measuring arm inclination. Master thesis, KTH Royal Institute of Technology. Available at:

Forsman, M., Dahlqvist, C., Yang, L., Wahlström, J., Hansson, G.-Å., 2015. Ny förenklad metod för heldagsmätningar av arbetsställningar och rörelser för huvud, nacke, rygg och överarmar - validitet och användbarhet [A new simplified method for whole-day measurements of postures and movements of head, neck, back and both upper arms - validity and usability]. Final project report to AFA Insurance. In Swedish with an English Abstract. Karolinska Institutet, Stockholm, Sverige.