| | Symbol | Description |
| | Mass of the wheel | | Mass of the frame | | , | Mass of precession frame for left and right | | , | Mass of gyroscopes for left and right | | Radius of the wheel | | Distance of frame’s centre of gravity from centre of wheel | | , | Distance of precession frame’s centre of gravity from frame’s centre of gravity for left and right | | , | Distance of gyro’s centre of gravity from precession frame’s centre of gravity for left and right | | , , | Moments of inertia of the wheel’s centre of gravity about the X,Y,Z axes, respectively | | , , | Moments of inertia of frame about the X,Y,Z axes, respectively | , ,
, , | Moments of inertia of precession frame’s centre of gravity about the X,Y,Z axes, respectively for left and right | , ,
, , | Moments of inertia of gyroscopes’ centre of gravity about the X,Y,Z axes, respectively for left and right | | Yaw angle of the robot | | Roll angle of the robot | | Pitch angle of the body | | Rotating angle of the bottom wheel | | , | Precession angle of precession frame for left and right | | , | Spinning angle of gyroscopes for left and right | | Torque of the bottom wheel | | Torque of precession system | | Torque of gyroscope system |
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