The agricultural case study is proposed by Kongskilde and it is focused on the Robotti agricultural autonomous platform. This robotic platform can be seen in the picture above and it features three main entities: guidance and control system, tractor frame and implements used to work the field.
Methodological and technical challenges
This system presents many different methodological and technical challenges but we have selected two key aspects in order to ensure safety and correct operation:
- Ensuring correct navigation in the field in which the robot is deployed, being able to steer the tractor frame according to the field shape, dimensions and topography. This implies correct usage of positioning data coming from multiple sensors and closed loop control of the robot actuators.
- Ensuring safety during operations, being able to lift the implements that are in contact with the field in case obstacles are detected. Obstacles are not known in advance and have to be detected during operation. These can vary in size. Examples of obstacles that can be found typically are stones, bird nests, deer or people (rarely but possible). Being able to react to obstacles does not only increase the operational safety of the robot but also decreases the environmental impact of farming.
The expected outcome of applying modelling is to be able to evaluate in a cost-effect way different system implementations and architectures responsible for robot navigation and operation. Additionally we aim at gaining confidence in the chosen design candidate through simulation of different operational conditions and scenarios. The results of these simulations could potentially serve as evidences in order to complement the documentation needed to get these kinds of machinery certified.
An additional expected benefit would be the introduction of a model-based engineering approach in some of the company’s engineering workflows as well as a progressive adoption of system engineering best practices.
The baseline technologies that will be used in the production of these models are:
- VDM-RT for modelling of the discrete-event behaviour of the system as well as the modelling of the overall orchestration logic behind the Robotti controller.
- 20-sim for modelling of continuous-time and physical system aspects. It is expected that VDM-RT and 20-sim models will run as a co-simulation in the Crescendo tool.
- Modelio and SysML in order to create high-level, abstract representations of the models and the system architecture. The intention behind the use of SysML is two-fold: first it would help to reason about the system architecture at a very high-level of abstraction and with visual models. Second, to facilitate the communication in multidisciplinary teams.