Example of an autonomous mobile machine: Automated straddle carrier

The point of this chapter is to demonstrate a real-life example of an autonomous mobile machine and what is considered in the machine design. The operation principle is shown, technological requirements for autonomous operation are presented and considerations towards skillsets and important factors related to the autonomous machine are pre- sented.

Autonomous machines for port operations include unmanned container handling ma- chines. Part of increasing productivity in a terminal is through automating a part of the operation. A part of operation includes picking containers from seaside, transporting con- tainers through operation area and stacking them on top of each other. An automated straddle carrier can perform this task without human intervention, but still relying on hu- man surveillance. Automation by automated shuttle carriers minimizes human error and improves safety. Unexpected interruptions that impact productivity and profitability can be avoided with automation. Other benefits include savings in terminal operating ex- penses, improving efficiency, better availability and site security and longer equipment lifetime. The operation is optimized so that it reduces fuel consumption. For instance, engine stops during equipment idle time and driving patterns are optimized through cal- culation. A view from above automated straddle carrier operation is presented in figure 8. (Kalmar, 2014; Alho et al., 2015)

An example of a terminal operation is presented in figure 8 where a ship-to-shore crane moves cargo containers from the ship to shore for the automated straddle carriers to pick up. Four automated straddle carriers move containers from seaside to a buffering zone. From the buffering zone, a larger container handling equipment picks up the container and places it on top of the container stack. The straddle carriers automatically adapt to changes in terminal throughput: If the machine is not required now, it will park away, but in case of need more equipment can be added on demand. (Alho et al., 2015)

The automated straddle carrier navigational capability is considered as autonomous. The vehicle navigation is based on virtual routes with an accuracy of few centimeters. This is achieved with two methods, magnet and radar navigation. Magnet navigation uses sen- sors on the bottom of the straddle carrier to detect magnets embedded in the pavement of the operation area. The benefit of this method is low cost investment on each straddle carrier, but downside is a large one-time infrastructure investment when installing the magnets. Radar navigation uses typically between 100 and 200 beacons installed on the operation site and the machine has to be in line of sight of at least three radar beacons. A radar-based system requires a lower investment on infrastructure, since the radar bea- cons are inexpensive and easily installed. Figure 9 presents a Kalmar straddle carrier and its technologies providing autonomous functions. (Alho et al., 2015)

Figure 8.Four red Kalmar automated straddle carriers pick up containers from shore

Awareness of environment and objects is provided by obstacle detection sensors and sensors on the side frames and spreader to pick and place containers with high reliability and accuracy. The automation of operation is not only enabled by the technologies onboard the machine. An infrastructure to support automation is required. The terminal layout requires change in order to enable automated operation. To support autonomous navigation of straddle carriers, radar beacons must be installed around the site and/or magnetic markers must be embedded in the pavement. A wireless network for commu- nication with the straddle carriers must be included, by installing radio frequency links that provide emergency stop and remote-control functions. To ensure safety, the opera- tion area must be restricted with fencing, safety infrastructure and access control. In ad- dition to the installations, instrumentations such as sensors and programmable logic con- trollers may have to be installed to the infrastructure in order to interface with straddle carriers. (Alho et al., 2015)

Adding automation by automated straddle carriers requires careful planning and exer- cising, and integrating new systems are to be considered in addition to new technical implementation. Systems such as Terminal Logistic System (TLS) and other systems are part of supporting the automated straddle carrier operation. TLS is responsible for conducting and optimizing planning, routing and execution of automated operations (Kal-

Figure 9.Kalmar Automated straddle carrier and some of its autonomy providing

technologies (1a Radar, 1b Magnet ruler, 2 and 6 sensors for automated picking, placing and detecting obstacles, 3 IMU for improving positioning, 4 communications for navigation reporting in real time and 5 encoders for calculating vehicle position). Modified from Alho et al. (2015) © Cargotec 2015.

mar, 2014). Thus, the planning and decision making is done outside the automated strad- dle carrier, making the operation dependent on a whole system, instead of a single ma- chine.

The design of a system using automated straddle carriers includes software integration of all levels of operation, from yard equipment to process automation, which have to be implemented according to clearly specified roles and interfaces between subsystems and business processes. This is ensured by testing and simulation: Laboratory environ- ments are used to confirm the execution of business processes, where all the subsys- tems are verified in end-to-end scenarios. Various software versions and complex de- ployments can be simulated in a virtual environment with an authentic TLS and vehicles. (Alho et al., 2015)

Maintenance of an automated straddle carrier is crucial: A manually operated straddle carrier can operate with some minor deficiencies, but automated version of such machine must be in perfect condition to deliver its full potential. Frequent preventive maintenance operations take place at planned intervals. Intelligent systems are used to provide infor- mation on machine fleet condition and performance. System such as Equipment Moni- toring System (EMS) (Kalmar, 2011) is used to provide information about machine status and fault diagnostics. The result of preventive maintenance is reduction of the total cost of maintenance, reduction of downtime and better equipment availability. (Alho et al., 2015)

New skillsets are required to perform such maintenance operations. A maintenance en- gineer with appropriate skills is required to enable the maintenance of automated equip- ment. Maintenance should be based on data, facts and analysis instead of operators reporting faults, reactive maintenance. Proper maintenance of an automated straddle carrier requires data mining and understanding the operation of automated systems and sensor technologies. (Alho et al., 2015)

The automated straddle carrier shows an example of important topics to consider in the design of an autonomous mobile machine:

- Implementing the overall system and technologies requires careful planning and executing.

- Software integration from machine onboard to operational system levels is im- portant.

- Maintenance requires a new type of skillset and methods based on data acquisi- tion, management and analysis.

- Supporting environment for machine navigation with wireless communications. - Supporting infrastructure for machine operations (e.g. TLS and EMS).

- Methods for ensuring safety such as restriction of zones and local training of em- ployees.