This study investigates the positional accuracy and deformation behaviour of a robotic system performing simulated Continuous Ultrasonic Welding of thermoplastic composites. Thermoplastic composites are attractive due to their high specific properties and can be processed with lower-cost and faster assembly methods. Using a custom-developed end effector on a KUKA KR560 robot, a series of welding motion tests were conducted to analyse lateral deviation and tilt errors during CUW, without activating ultrasonic vibrations. High forces involved in the process result in consistent horizontal slip and tilt at motion initiation, attributed to static friction and stored mechanical energy in the system. Measurements from a laser tracker, force/torque sensors, and triangulation sensors revealed that robot pose and weld-line distance significantly influence these deflections. Notably, deflections were consistent and repeatable, suggesting potential for compensation via calibration or feedback control. Additionally, internal deformation within the end-effector structure and Force Torque sensor assembly contributed to the observed positioning errors. Recommendations include improving frame symmetry and stiffness to reduce mechanical distortion. These findings aim to support more accurate and reliable Continuous Ultrasonic Welding implementation in aerospace-grade composite manufacturing. ... Read more

Double-curved composite structures that are manufactured via automated fiber placement, such as pressure vessels, can take advantage of tow steering to reduce weight. This design freedom comes with the cost of adding internal normal stresses to the tow, possibly leading to wrinkles or pull up. The present work investigates tow pull up both experimentally and analytically and details a correlation between tow pull up and the minimum critical steering radius, where the material tackiness and the modelled plate’s length are found to be the most influential parameters. The experimental determination of the material tackiness is the next step to improve the predictive capabilities of the proposed model. ... Read more

This article presents a readout integrated circuit (ROIC) for capacitive touch-screen panels (TSPs) employing an amplitude-modulated multiple-frequency excitation (AM-MFE) technique. To prevent charge overflow, which occurs periodically at the beat frequency of the excitation frequencies, the ROIC modulates the amplitude of the excitation voltages at a mixing frequency derived from the excitation frequencies. Thus, the ROIC can sense the charge signal without charge overflow and maximize the signal-to-noise ratio (SNR) by increasing the amplitude of the excitation voltages up to the sensing range of the readout circuit. The proposed ROIC was fabricated in a 0.13- $\mu \text{m}$ standard CMOS process and was measured with a 32-in 104 $\times $ 64 touch-screen panel using 1 and 10 mm metal pillars. It reduces charge overflow up to 33.9 dB compared to operation without AM-MFE. In addition, the ROIC achieves a frame rate of 2.93 kHz, and SNRs of 41.7 and 61.6 dB with 1 and 10 mm metal pillars, respectively. ... Read more