Distributed Experiment Steering

Name

Distributed Experiment Steering

Context

The pattern applies to a system with the following characteristics:

  • An experiment plan exists that lists the predetermined actions to be performed while running the experiment, including potential parameter changes based on experiment progress.

  • A local or remote experiment controller exists that executes the predetermined actions to be performed while running the experiment.

  • A remote experiment analyzer exists that orients the observed information for the experiment controller.

  • Sensors exist to allow for measuring experiment progress.

  • Actuators may exist to allow for moving or controlling something before, during and/or after running the experiment.

  • Additional sensors may exist to allow for measuring something before, during and/or after running the experiment.

  • Instruments may exist that contain sensors and potentially actuators.

  • Robots may exist that contain actuators and potentially sensors and that execute predetermined actions from the experiment plan in an automated or autonomous fashion.

  • A component may exist that post-processes raw experiment data, such as to identify features.

Problem

Certain predetermined actions need to be performed while running an experiment to positively influence experiment progress. Experiment progress is analyzed and optionally also judged/controlled remotely, incurring a potentially significant communication delay.

Forces

Only pre-experiment conditions and changing conditions during the experiment are considered in performing the predetermined actions while running an experiment. Post-experiment conditions are not considered.

Experiment progress is analyzed and optionally also judged with significant communication delay to remote components. Proper computational analysis and decision making capability does not need to be local, but must be able to respond within a certain amount of time.

Solution

The is pattern implements the Experiment Steering strategic pattern using an OODA loop control. The Orient component and optionally the Decide component of the of the OODA loop control are remote, i.e., physically located and connected in a way that does incur a significant communication delay between the components.

As in the Experiment Steering strategic pattern, an experiment controller executes an experiment using a predetermined experiment plan and changes the plan’s parameters during execution based on experiment progress (Fig. 15). The plan’s execution is autonomous, performed in a closed loop control and may involve human interaction. The controller may monitor the experiment for safety reasons. The plan contains a complete description of the predetermined action to be performed for running the experiment, including any safety-related responses and how to analyze and judge experiment progress and change the plan accordingly. Raw experiment data may be post-processed by an optional component, such as to identify features.

Pattern components and control/data flow

Fig. 15 Distributed Experiment Steering architectural pattern components and control/data flow

The OODA loop control is formed by sensors that observe the experiment, an analyzer that orients the observed information, an experiment controller that decides on appropriate actions and actuators that perform the appropriate actions. As some components of the OODA loop control are remote, component-local storage and explicit data transfer between components may be used for sensor, analyzer and controller data. Control messages between these components orchestrate the control flow.

This pattern offers a closed OODA loop control with safety-related feedback on the experiment and feedback on experiment progress. Experiment plan execution is autonomous, i.e., its list of actions changes during execution based on feedback and is performed without external or human intervention that can unnecessarily hold up execution. Only 1 experiment is being controlled. There is a significant communication delay to remote components in the closed OODA loop control, as the experiment progress analysis is remotely and the experiment controller may be remote as well.

Resulting Context

An experiment is executed autonomously using a predetermined experiment plan, with the plan’s parameters changing autonomously during the experiment based on experiment progress. Experiment progress is analyzed and potentially also judged remotely, i.e., with significant communication delay to remote components.

Related Patterns

This architectural pattern implements the Experiment Steering strategic pattern.

In contrast to this architectural pattern, the Local Experiment Steering architectural pattern analyzes and judges experiment progress locally, i.e., without significant communication delay to remote components.

Examples

An autonomous microscopy science use case [B29] implements the Distributed Experiment Steering architectural pattern, as an ongoing STEM experiment is controlled by remote analyses of periodic experiment data. At the architectural pattern level of abstraction, the individual pattern components are as follows:

  • In addition to the properties identified by the Experiment Steering strategic pattern, the experiment controller is either local or remote and may feature a GUI or some other HMI.

  • The actuator is part of the STEM and moves the scanning electron beam.

  • The test is performed in the STEM experiment determines the properties of microscopic structures.

  • The sensor is part of the STEM and provides the raw microscope data.

Known Uses

This architectural pattern is used in every experiment, where live feedback of remotely analyzed experiment data is being used to autonomously change experiment parameters. Given the potentially significant communication delay between the experiment and the remote analysis, real-time feedback loop solutions are limited.