Sim-to-Real Transfer of Robotic Control with Dynamics Randomization

Simulations are attractive environments for training agents as they provide an abundant source of data and alleviate certain safety concerns during the training process. But the behaviours developed by agents in simulation are often specific to the characteristics of the simulator. Due to modeling error, strategies that are successful in simulation may not transfer to their real world counterparts. In this paper, we demonstrate a simple method to bridge this "reality gap". By randomizing the dynamics of the simulator during training, we are able to develop policies that are capable of adapting to very different dynamics, including ones that differ significantly from the dynamics on which the policies were trained. This adaptivity enables the policies to generalize to the dynamics of the real world without any training on the physical system. Our approach is demonstrated on an object pushing task using a robotic arm. Despite being trained exclusively in simulation, our policies are able to maintain a similar level of performance when deployed on a real robot, reliably moving an object to a desired location from random initial configurations. We explore the impact of various design decisions and show that the resulting policies are robust to significant calibration error

Desiccation tolerance of intermediate pomelo (Citrus maxima\textit{Citrus maxima} \u27Mansailong\u27) seeds following rapid and slow drying

We investigated the effects of rapid and slow drying regimes on desiccation tolerance (DT) of developing pomelo seeds. Slow-dried seeds harvested at 130, 180, 210 or 235 days after anthesis (DAA) had greater DT than rapid-dried seeds (P < 0.05); However, when seeds were collected at 90 or 150 DAA, there was no significant difference in DT between the two drying treatments. Furthermore, the DT improvement from slow drying gradually decreased as seeds matured during the period from 180 to 235 DAA. It was concluded that the DT of intermediate $\textit{C. maxima}$ \u27Mansailong\u27 seeds following slow drying was higher than following rapid drying, but it depended on the seed developmental stage