Venti is developing self-driving container trucks, aka Autonomous Prime Movers (APMs) to move shipping containers between cranes within the PSA Singapore port. The project aims to alleviate the strains in the supply chain by addressing manpower shortages and further improving operational efficiencies. The port offers unique challenges for the deployment of self-driving vehicles such as high environment change (variable stock of stacked shipping containers, moving cranes), high occlusions from large actors and structures, all-weather operational demands, tight positional tolerances for interfacing with cranes, interfacing with port specific infrastructure, specialised port traffic patterns with corresponding traffic rules, and control of long articulated vehicles (truck with trailer) under variable loading up to a maximum of 65 metric tonnes. Other problems are common to urban traffic scenarios, such as mixed traffic (human and robot) driver navigation of intersections and lane changes with travelling speeds of up to 40 kph, which demands APM perception range of 150m.
In addition to considering the safety and performance of a single APM, we also must ensure a safe and performant operation of a fleet, supported by remote operations and reliant on external systems such as wireless network infrastructure. Complimenting the autonomous system with remote operations can ensure more uptime and safe handling of exceptional cases, but we must further ensure that the functional safety design brings the vehicle autonomy to a safe state for handover to the remote operator, so that the remote operator can resolve the situation safely. Loss of network connectivity or high latencies could further compromise the remote operator's ability to control the APM, hence remote operations functions and fail-safes need to be designed with such limitations in mind. Designing failsafe manoeuvres will require a deep understanding of the multi-objective functions reflected in system requirements, where sometimes vague text definitions such as drive defensively, may need to be translated into code that the robots can interpret.
The focus of the project will be on systems design for the functional safety of a robot and human combined system of multiple APMs and remote operators connected over a wireless network. This may include following steps of ISO standards such as hazard analysis and risk assessment, failure modes and effect analysis, the definition of critical safety and performance metrics for triggering failsafe actions (safe stop, request intervention, etc), and quantification of residual risks. The scope may further include identifying patterns in network degradation, where if network degradations are predictable due to effects of weather, shipping container movements, vehicle speed, or other observable environmental factors, fleet management mitigations can also be designed (ie detour to avoid network dead zones).a
