Tracking Tasks

1. Introduction

The Tracking Manager in UniTherapy allows users to define their own tracking task by editing a basic spatial tracking pattern (Rectangle, Cross, Circle and Random) and then customizing settings to build up tracking point lists.

UniTherapy currently provides two types of tracking modes:

Discrete mode: Point-to-point tracking, where the target window jumps to a new location and the subject's goal is to move the input device cursor (displayed as a green ball) position into the target window. The target position is selected from the user defined tracking point list, to be implemented in a time sequence. It is possible to adjust general settings (e.g. target size, target shape, force field) and track settings (e.g. track range, track pattern, timing).
Smooth mode: Smooth tracking (also call pursuit tracking), where the subjects is to move the cursor (e.g., green ball) to follow the continuous moving target as accurately as they can. "Preview" of the upcoming path also may be provided.

There are several inherent features provided by UniTherapy:

Multiple input interfaces, such as pointing devices and speech interface can be used by the subject to do the tracking task.
Once the ROM (range-of-motion) protocol is completed, the user can choose options that enable the tracking points to be mapped to points within the subject’s ROM or the subject’s position within their ROM to always be warped to full window workspace.
Assistance/Resistance/Perturbation force can be used with tracking task. Using this feature, the users can apply different force according to the subject’s performance. Note that this can be used to provide forces that assist the user in reaching a target which is outside of their ROM.

The settings can be divided into pattern settings and general settings. Pattern settings only apply the selected tracking pattern while general settings apply to the whole tracking task.

Details on Pattern Settings

Four basic patterns are available: Rectangle, Cross, Circle and Random. To build up a tracking task, user can select one or many pattern and edit their settings. One pattern settings may not apply to all the patterns.

Settings	User Interface
Orientation: Tracking can go either Clockwise or Counter-Clockwise. It only applies to Rectangle and Circle. [Default = Counter-Clockwise]
Total Points: In point reaching task, total points define how many points generated with the selected pattern. It only applies to Circle and Random. For Circle, the points are evenly distributed by angle. [Default = 4, Min. =4, Max. = 20]
Horizontal Points and Vertical Points: In point reaching task, horizontal points define how many points generated in the horizontal line, and vertical points define how many points generated in the vertical line. It only applies to Rectangle and Cross. [Default = 3, Min. =2, Max. = 10]
Training Area means the pattern will be created in the defined area. User can define the area by using slider bar or drawing in the tracking window. The value is between 0 to 1, which represents the ratio to the height (Right and Height) or the width (Left and Width) of the full workspace.

Generally settings usually apply not only to one pattern but the whole tracking task.

Settings	User Interface
Target Shape: The target shape can be rectangle or Circle.
Target Size: The larger the size is, the easier the subject can see and reach. [Default = 40, Min. = 30, Max. = 150] Because the subjects are required to move the green ball into the target and stay for a certain time, target shape and size will change the difficulty of the tracking task.
Assistance/Resistance/Perturbation feature can be used together with Tracking Task, which provides assistance/resistance force to the subject during their tracking task. Four different types of force are available. At this stage, user can only select one type of force at one time. When using Force-reflecting device: Spring (stiffness): a spring-like force, the offset of which always is the center of the workspace. Human: a remote human (e.g., practitioner) can use another device to apply spring-like "assist" or "resist" forces, in essence moving the resting position of the joystick for the user. White noise: the force feels like a random perturbation, which increased the difficulty of the task. *Damper: a damper force which cause the viscous effect during the movement, like moving through water (low viscosity) or mollassis (highly viscous). The range* of the magnitude is [-100, 100], where 0 is no force. The sign indicates “direction” of the force. The bigger the absolute value of magnitude, the stronger the force will be. For the spring force, a positive sign always pulls the user toward the target (assists them) and a negative always pushes them away from the target. offset position. For the damper force, the positive sign always resists the users movement (“slower”) and the negative sign always augments any movement toward the target. (The red color indicates positive, the green color indicates negative.)
By selecting Enable Preview, the tracking task turn to full preview one, which mean it will show all the points in tracking list from the beginning. It will give the subject a hint where the target will go during the whole tracking task. It is also interesting to see how the length of the preview window can affect the subject’s performance, which could be another setting here.
A significant difference between point reaching and preview tracking is one is discrete and another is continuous. So only in continuous task (preview tracking), the target will move continuously by itself in a certain speed Target Speed: defines how fast the target moves. [Default = 5, Min. = 1, Max. = 20]
Task length: defines how long the tracking task may take. Either the subject finishes the task or the task length passed this predefined value, the task will end. [Default = 60 seconds, Min. = 10 seconds, Max. = 60 seconds]
Seconds for target to auto-reset: defines how many seconds the target will automatically jump to the next predefined point. Sometimes, the subject cannot reach the target at certain area. To avoid stop of the whole tracking task, the target will automatically jump to next predefined point; at the same time, the point which the subject cannot reach will be marked as a failure point. This setting may only apply to Point Reaching Task. [Default = 5 seconds, Min. = 1 seconds, Max. = 20 seconds]
Seconds on target for success: defines after how many seconds the subject stay in the target, it will be counted as successfully reaching that target. Sometimes it is necessary to lower this value to observe the subject’s reaction time length. [Default = 1 seconds, Min. = 0 seconds, Max. = 5 seconds]