Co-designing with children in an online environment is increasingly important due to external factors, such as the COVID-19 pandemic, and the diversification and inclusion of youth participants. Many prior studies about co-design with youth focus on co-located or asynchronous online sessions. However, conducting synchronous online co-design sessions adds layers of complexity and uncertainty to collaboration. This paper introduces a model explicating factors to consider when co-designing with children synchronously in an online space. We examined ten consecutive intergenerational participatory design sessions online where children (ages 7-11) and adults designed new technologies. Along with highlighting unexpected moments and interactions, we use theories of improvisation to guide our understanding of dynamic situations that are out of the control of researchers. This work contributes to improving theoretical understanding of improvisation as a method of inquiry for co-designing with youth, and offers practical suggestions for suitable online co-design techniques and implementation.

Warning systems play a crucial role in the takeover of conditional automated driving. However, the widely used single-stage warning systems in takeover had inevitable and critical issues in situation awareness (SA), driving stress, and takeover performance. As such, two-stage warning systems might be an optimal solution to alleviate these problems. On this basis, this study investigated the effect of warning types (single-stage vs two-stage warning systems) and non-driving related tasks (NDRTs) (playing Tetris game vs monitoring automated systems) on takeover. A total of 32 participants were recruited to join our driving-simulated study. These participants responded to different types of takeover warning systems upon receipt while engaging in NDRTs. Simultaneously, the SA, physiology stress, takeover performance, and acceptance data of the participants were recorded. Results showed that the drivers exhibited higher SA, lower physiology stress, better takeover performance, and higher acceptance ratings in the two-stage warning systems than in the single-stage warning systems. In conclusion, two-stage warning systems are promising in improving takeover safety based on connected vehicle technologies in the future. These findings can provide some guidelines for designers and engineers when applying the warning systems in automated driving.