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Table 1 Summary of previous COACH systems.
| COACH Version | Tracking System | Decision-making system | Prompting system | Number of Subjects* | Related Publications |
|---|---|---|---|---|---|
| Version 1 | Pattern wristband worn by the user | Neural networks interacting with a hard-coded taxonomy | Audio prompts, with one prompt for each step | 10 | [22, 33] |
| Version 2 | Using background subtraction to isolate the user's hands. Tracking of hands and task objects (i.e. soap and towel) using a preset colour model. | Fully observable Markov decision process (MDP). This technique assumes the world is fully observable; it does not take into account hidden variables, such as user responsiveness. | Audio prompts with three levels of assistance (minimal, moderate, and maximal) for each step. | 4 | [20, 37–39] |
| Version 3 (system presented in this paper) | Colour based flocking. | [Belief monitoring system & policy] Partially observable Markov decision process (POMDP). This model takes into account hidden variables and is able to make decisions in conditions of uncertainty. | Audio and audio-video prompts with three levels of assistance (minimal, maximal, and maximal + video demonstration) for each step. Encouragement and a reminder regarding the activity the user is attempting added. Professional actor recorded prompts. | 6 | [18, 19, 21, 23, 25] |
