Human-Computer Interface in SIPE-2

In practical applications, natural pictorial representations are necessary for a human user to understand the domain knowledge, the plan, the planning process, and the execution of the plan. SIPE-2 provides a powerful graphical user interface (built on Grasper-CL). Graphical tools can be used for the following purposes:
  1. inputting domain knowledge and creating operators
  2. following and controlling the planning process
  3. viewing complex information (including plans, operators, and world descriptions) as graphs on the screen
SIPE-2 has five command menus. The PROFILE menu has commands for setting defaults that allow the user to customize the behavior of the system. The DOMAIN menu has commands that apply to the problem domain as a whole, e.g., inputing and inspecting a domain. The PLAN menu has commands that apply to a specific plan, including executing a plan and solving a problem to produce a plan. The DRAWINGS menu has commands that draw various SIPE-2 structures. Objects that can be drawn include plans, operators, the sort hierarchy, the initial world model, and problems. Finally, the NODE menu has commands that apply to specific nodes in the currently drawn plan.

Knowledge Acquisition

Graphical tools are available for knowledge acquistion. SRI's Act-Editor supports graphical displaying, editing, and inputing of Acts. SIPE-2 operators, plans, and problems can all be represented as Acts. The Act-Editor provides a graphical knowledge-editor for both SIPE-2 and SRI's Procedural Reasoning System, since Acts can be translated into either system. SIPE-2's sort hierarchy can be created, viewed and edited using SRI's generic knowledge base editor, the GKB-Editor.

Controlling and Viewing Planning

SIPE-2 allows the user to control, when desired, many aspects of the planning process. The user can decide when to apply certain planning algorithms (known as plan critics), can choose which operator to apply after the system has determined which ones are applicable, and can choose which object to use for a particular action. At any of these choice points, the complete power of the interface is available for inspecting data structures (e.g., an operator can be drawn before choosing it). The option of planning automatically for either one abstraction level or for the rest of the plan is available. All choices are kept so that different alternative plans can be developed simultaneously.

The ability to understand what SIPE-2 is doing is enhanced by the ability to highlight a node on the screen whenever the system is making a decision about that node, e.g., planning for the node, choosing an operator for the node, or choosing instantiations for the variables at that node. Actions involved in resource conflicts can be highlighted when interactive solution of resource conflicts has been requested. If an ordering of two actions is chosen, SIPE-2 will incrementally highlight and draw ordering links as they are added. In particular, it flashes the first action, then draws the ordering link, and then flashes the second action. This gives an excellent visual depiction of how the plan is flowing.

During automatic planning, SIPE-2 provides a movie-mode in which the system constructs pictorial representations of the plan as it is being constructed.

Viewing Plans and Knowledge

SIPE-2 automatically lays out the actions of a new plan and gives the user several options concerning which actions to display and what information to display for each action. Many types of information can be depicted graphically. For example, one can highlight all the successors/predecessors of an action, all the actions unordered with respect to an action, all actions that use a certain resource, or all the actions that accomplish a certain condition. As another example, the sort hierarchy can be displayed graphically as a tree to help ensure its correctness. Clicking on an object in the hierarchy will pop up a window displaying its attributes.

The following screen dump from SIPE-2 shows a plan depicted graphically and the commands available in the DRAWING menu. This image shows an oil-spill--response plan at a high level of abstraction. The green hexagons are goals still to be solved and the blue capsules are actions.

View full size in color, or View full size in greyscale.

After expansion to the lowest level, this plan may contain hundreds of actions. Large plan drawings do not fit on the screen in their entirety, and are difficult to visualize. The interface provides several techniques for viewing them.

A picture of a birds-eye view of a joint military operations plan is also available, together with an image showing more detail of some of the nodes.

SIPE-2, GKB-Editor, Act-Edtior and Grasper-CL are trademarks of SRI International.
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David E. Wilkins
Last modified: Wed Feb 5 18:11:49 1997