An example of this is the Quha Zono mouse. Gyroscopic Mice: mice that track the movement of the body using a gyroscope and translate this movement into mouse placement on the screen. As they move their head around, the cursor on the screen moves accordingly. The dot is usually worn by the user on the forehead, bridge of the nose or glasses, if worn. Head Mouse: the specialist head mice use IR cameras to track the movement of a reflective dot. Many of the mice are controlled with the hands but there are others which can be used with the feet, elbows, chin, head or mouth. This can be as simple as a wireless version of the standard mouse, a joystick style mouse, a roller ball or a track pad. There is a large range of mice available that vary from the standard mouse.
As with text entry there are a range of hardware options and software support for navigation around the computer. Most computers require control of a cursor, although on some touch screen tablets, the cursor is not always obvious. It requires diaphragm control with sufficient strength, and may not benefit those who continuously use ventilators, such as those with SCI at level C2. SnP needs regular cleaning and maintenance due to being exposed to saliva and food residue. Another major limitation of the SnP is lack of proportional control, as opposed to a joystick or a mouse, which can provide a much easier and smoother control over different movements, such as acceleration and deceleration of a PWC or movement of a cursor on the screen in arbitrary directions, respectively. It only offers a limited number of direct choices (four commands: soft sip, hard sip, soft puff, hard puff), which should be entered sequentially, one-at-a-time. Despite being quite popular, this AT is slow, cumbersome for complicated tasks, such as computer access, and offers limited flexibility, degrees of freedom (DoF), and adaptability to user's remaining abilities. SnP is a relatively simple, low cost, switch-based AT, which allows its user to control a powered wheelchair (PWC) or manipulate a mouse cursor by blowing and sucking through a straw ( Figure 2). The command history window is the window in the MATLAB environment that lists all the previous commands entered at the command prompt, which is helpful for recalling work that was done in a previous session. The details of the workspace will also be explained in Chapter 3 on Functions.
The workspace window is the window in the MATLAB environment that lists all the variables currently being used in the workspace. The current directory window is the window in the MATLAB environment that lists all the files currently stored in the current directory. When you see this symbol in the text or in examples, it means that the action is taking place at the command window. The command prompt is where you can type your commands in the command window and is denoted by the symbol ≫. The command window is the window in the MATLAB environment where commands are executed and MATLAB’s responses are displayed. The current directory will be explained in greater detail in Chapter 3 on Functions. You can change the current directory by clicking the down arrow or the button with an ellipsis symbol (…). The current directory is the folder in your computer where files will be saved and where the files you will have direct access to are stored. The MATLAB environment consists of the current directory as well as four windows: the command window, the current directory window, the workspace window, and the command history window. The MATLAB environment is a text-based visualization tool that allows you to interact with MATLAB.