Prototype Design: Physical Interface

Overview
The next step in prototype design is to extend the 'shopping trolley handle' idea. Obtaining a good design for the physical device is crucial in providing the user with a natural and enjoyable shopping experience. There are a number of things to consider when designing this kind of hardware:
For example, one very common condition that the elderly suffer from is arthritis, meaning movement of joints such as the wrists and fingers can be very painful. This provides a reasonable obstacle when design hardware for the elderly that relies mostly on physical input.
It is therefore essential that the trolley handle relies on movement that will not cause elderly users any potential pain. The trolley handle device will therefore encompass two types of movement; forward/back and left/right. Below is an illustration of how the device will look:

Movement
The two types of movement will come from different parts of the device; the trolley handle swivels from the center point, similar to the movement of the handlebars on a bike. The actual distance the handle can turn left or right will be restricted to ensure minimal fatigue or stress for the user. The forward and backwards movement is controlled by a pivot at the base of the device. As with the left and right commands, the range the handle can be pushed will be limited.

Commands
The device will include four colour coded buttons, mounted onto the handlebar section. Inside each button is a LCD screen that will display the function of that button. These functions will also be display on the output screen (i.e. headset or projector) to ensure the user knows exactly what each button does.
Location
It is important to consider where the user will actually use the system. With elderly users, it is likely that the product could be used in a number of different situations. For example for some elderly users might want to use the system while sat at a table, and others may prefer sitting in a comfortable armchair. For this reason, the base of the device is designed to be compatible with most situations. The wide base means that it could be placed on a table top, either with sucker pads or adhesive strips. The central pole however means that the base could also be placed under the user's legs while sitting down, using the weight of the person's legs to hold it steady. This will result in a much more relaxing posture while shopping, as well as offering the user flexibility as to how and where they do their virtual shopping.