Abstract
Pneumatic ejection has dominated sensor-based sorting for decades, yet diffuse air jets cause bycatch at high mass throughput, and compressed-air generation accounts for a large share of operating cost. We propose (i) a grid-based sorting architecture replacing the conventional single nozzle bar with a two-dimensional grid, and (ii) impact-based mechanical actuators within the grid. Together, these eliminate compressed air entirely while increasing spatio-temporal resolution by leveraging redundant particle–actuator assignments. To coordinate online ejection—deciding which actuators to trigger and when—we formulate sorting as a finite-horizon soc problem and introduce mtcr. mtcr integrates olf soc, mixed discrete–continuous-time modeling, situation-aware action-space reduction, and a greedy rollout heuristic, supported by analytically tractable evaluation of expected sorting costs. In high-mass-flow simulations with equal accept/reject ratios, mtcr maintains both tnr and tpr above 90 , demonstrating effective actuator coordination and bycatch reduction. Laboratory experiments on a 56-solenoid prototype show that the grid significantly exceeds a state-of-the-art pneumatic chute sorter in rejection performance at matched bycatch level, with actuation energy being at least 79 times lower. Grid-based mechanical sorting thus offers a promising route toward precise, energy-efficient separation for cost-sensitive industries such as recycling.