Experiment Steering

Name

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.

  • 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.

Problem

Certain predetermined actions need to be performed while running an experiment to positively influence experiment progress.

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.

Solution

An experiment controller executes an experiment using a predetermined experiment plan and changes the plan’s parameters during execution based on experiment progress (Fig. 8). 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 actions 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.

Pattern components and control/data flow

Fig. 8 Experiment Steering strategic pattern components and control/data flow

This pattern offers a closed 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.

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.

Related Patterns

This strategic pattern is an extension of the Experiment Control strategic pattern with an added closed loop control and feedback on experiment progress. The Design of Experiments and Multi-Experiment Workflow strategic patterns can be extended using this strategic pattern for autonomously executing a predetermined experiment plan, with the plan’s parameters changing autonomously during experiments based on experiment progress.

This strategic pattern is implemented by the Local Experiment Steering and Distributed Experiment Steering architectural patterns.

Examples

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

  • The experiment plan contains a complete description of the predetermined actions to be performed for running the experiment, including any parameters for operating the STEM, safety-related responses and how to analyze and judge experiment progress and change the plan accordingly. The experiment plan also contains the goal of the experiment to steer it in the right direction and to stop its closed loop control upon completion.

  • The experiment controller executes an experiment using a predetermined experiment plan and changes the plan’s parameters during execution based on experiment progress. The plan’s execution is autonomous, performed in a closed loop control and may involve human interaction.

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

  • The experiment result is a combination of raw and analyzed STEM data and insights derived from this data.

Known Uses

This strategic pattern is used in every experiment, where live feedback of experiment data is being used to autonomously change parameters during the experiment. Known uses range from having simple PID controller to complex probabilistic approaches or domain science informed AI in the feedback loop.