Quadrotor mounted Inverted Spherical Pendulum Test Stand - Design and Characterization

This paper presents preliminary investigations on the motion of quadrotor mounted test-stand. The test-stand is designed based on inverted spherical pendulum. The pendulum has a platform on which a quadrotor UAV is mounted acting as an actuator. The pendulum has three degrees of freedom with radial, polar and azimuthal directions. The length of the pendulum is adjustable and the polar angle is constrained by ±25 degrees and has 360 degrees of rotation for azimuthal angle. This results in motion of the platform constrained to move in a a conical space. The torque inputs along roll, pitch and yaw directions of the UAV results in motion along radial, polar and azimuthal directions. To characterize the test-stand, static thrust force measurements are carried out using load cell and kinematics of the UAV are measured using IMUs. As an initial investigation, the motion of the test-stand is studied by applying torques along the roll, pitch and yaw directions. The results show that the test-stand is moving as expected with higher sensitive in angular velocity about for pitch torque input. The accelerations along x and z directions are prominent. A model is derived for test-stand will be used for further validation in future.