Piezo actuated vibratory feeding with vibration control

This research investigated the effect of decoupling the motion of a conventional vibratory feeder in order to develop a one-axis vibratory sliding mode for feeding tiny delicate parts that could ultimately be adapted to two axes. This research investigated a new type of vibratory drive by employing a piezoelectric actuator. In a decoupled design, the action of the horizontal and vertical vibration would be separately controlled to achieve a desired part trajectory and consequently the feed rate of the part. A computer control scheme was used to develop voltage input waveforms to control these actuators to produce movements that cause the parts to move forward relative to the track and overcome backsliding and other inefficient feeding motions. There are two advantages to this type of design. First, it can handle the parts in a more controlled manner by keeping them in constant contact with the track while maintaining a high conveying speed. This results in good protection for fragile parts. Secondly, this concept results in feedback control schemes that could allow the computer to adjust the drive waveforms to optimize feeder performance. Due to the non-sinusoidal nature of driving waveforms, the higher harmonic components can excite undesired deformation of the responding trajectory. A self-tuning control based on dynamic system identification was employed to counteract the higher harmonic effect. A one-dimensional hardware model is built and experiments were conducted to verify the precision and feasibility of the controlled actuation.