Caterpillar has been developing the foundation for autonomy over the past four decades. Its portfolio of building-block strategies includes operator-assist features, remote-controlled machines, semi-autonomous machines, fully autonomous machines, and a completely integrated worksite. Autonomy on a large scale offers companies the solution of removing process variability resulting in unprecedented improvements in safety, availability, and productivity.
At the recent SAE 2016 Commercial Vehicle Engineering Congress, Matt Glover; Senior Project Team Leader, Command for Dozing; Advanced Technologies and Solutions Division, Caterpillar, discussed “Caterpillar’s Autonomous Journey.” Here, we briefly summarize Caterpillar’s building-block strategy for autonomy.
All Caterpillar remote control, semi-autonomous, and fully autonomous machines are designed to be operated in manual mode with an operator in the seat. Cat autonomous machines have the same performance and functionality of the standard machine models when operated in manual mode. All Caterpillar autonomous base machines are fully electrohydraulic (EH) machines. This enables the electronic controls to be seamlessly integrated into the machine without the need for additional hardware or third-party systems.
Caterpillar uses a building-block approach to autonomy utilizing well-established subsystems. This starts with a fully EH machine and begins to add operator-assist features or automated features to the base machine. In addition to being a building block to autonomy, the operator-assist features allow novice operators to dramatically increase in productivity and efficiency as manual operators in the machine. These operator-assist features are critical in allowing efficient remote operation of machines as the operator moves off of the machine utilizing either a remote console or operator station. Semi-autonomous machines are the next step on the journey and involve an operator periodically interacting with the machine or a group of machines. A fully autonomous machine requires no direct operator control and a completely autonomous job site would have no operators in the pit running equipment.
With a scalable semiautonomous tractor system, a customer can order a machine, upgrade to line-of-sight remote control, upgrade to an operator station (requires additional external networking), add the vision system to upgrade it to non-line-of-sight-remote control, and finally add the semi-autonomous support to be able to operate up to four machines from a single operator station. A customer is able to choose the solution that meets their needs and they can upgrade at any time as their requirements or conditions change.
Each piece of equipment intended for autonomous operation is equipped with specific components and software that allow them to operate autonomously in their distinct application. While uniquely configured, all of Caterpillar’s Cat Command machine products include the following subsystems: positioning, planning, perception, and wireless communications.
Knowing the precise location of autonomous machines, loading tools, auxiliary machines, light vehicles, and stationary equipment is critical for proper system operation. For surface mine sites, the systems depend upon a GPS base station to send correction signals to the onboard positioning systems allowing the global position to be translated into a local coordinate system with sub-centimeter accuracy. Once the autonomous work area is surveyed and a virtual map is created, the location of each vehicle or piece of mobile equipment must be tracked.
Each autonomous machine is equipped with multiple Global Navigation Satellite System (GNSS) antennas, receivers, and an inertial measurement unit (IMU). A single GNSS receiver reveals the machine’s position and speed; however, multiple receivers in combination with the IMU allow the machine to understand its orientation even at rest. In the event that an autonomous machine loses the ability to determine its position, it will come to a controlled stop and await further instructions.
The planning system can be broken down into three subtasks: site planning, job planning, and task planning. Site planning is the broadest view of autonomy, including all machine types and the coordination between the machines and specific job sites. Job planning is planning at a specific job site or within an automated machine type. Task planning is the planning of specific tasks for an autonomous machine and typically includes two major task planning functions—navigation and application-specific tasks. Navigational planning is responsible for taking a machine from point A to point B while avoiding obstacles. For loading or grading machines, the application-specific task would be excavation planning or moving dirt from one location to the other in an efficient manner.
Perception is used to prevent autonomous machines from contacting people, vehicles, or other objects. Sensors are used to monitor the immediate work area, identify obstacles and hazards, and determine an appropriate response without human intervention.
A critical, and often overlooked, piece of the autonomy system is the wireless network that ties all of the systems and communication together. Without constant communication between the machines and office, autonomy is not possible. Robust 24/7 communication is required in the demanding, nonstop environment of a mine. Communications are required to be strong over the entire area where autonomous machines are expected to operate.
Key to success
Application of advanced technologies requires not only innovative systems, but integration with people and process. To get the most from the automation benefits, any industry or application must alter the current process to take advantage of the consistent and optimized operation of autonomy. Operating costs are reduced and the benefits of autonomy are magnified through improved utilization, greater process consistency, and increased execution of best practices. Having autonomous technology is an advantage, but the maximum benefits from technology are achieved when people, process, and products are integrated and changed concurrently.
This article is based on SAE International technical paper 2016-01-8005 by Matthew Glover of Caterpillar’s Advanced Technologies and Solutions Division.