Fig. 1
From: Novel tag-based method for measuring tailbeat frequency and variations in amplitude in fish
Illustration of how the accelerometer measurement axes of the tag (X, Y and Z) relate to orientation axes of the fish (X,b, Y,b and Z,b). Assuming that X is aligned with X,b, pitch (Θ) will define the angle between X and the horizontal plane, while the roll (ɸ) and yaw (ψ) angles will define used to describe the deviation between the Y and Y,b and Z and Z,b, respectively