On the Modules and Key Techniques of Cleaning Robot (1)
(to be continued)
2) Power supplier
Power supplying technique plays an important role in robot cleaners for it is the driving force of robot cleaners. Movable power supply should be able to meet multiple requirements of robot, for example, providing driving force for robot’s locomotion, stable voltage for controlling robot’s circuit, and power for cleaning module. The ideal power-supplier ought to maintain stable voltage in discharging power, to discharge efficiently, be rechargeable, be low in cost, etc. This demands robot designers to produce a suitable battery.
Presently, robot cleaners basically adopt battery as power supplier, such as primary battery, secondary battery and fuel battery. Primary battery used in robot cleaners mainly refers to lithium battery. Lithium battery has strong electromotive force, high density in energy, and is able to work in a wide range of temperature and is quite slow in self-discharging, which makes it a favorable power supplier for robot. Secondary batter, also called storage battery, includes lean-acid battery, silver-zinc battery, nickel-cadmium battery, nickel-zinc battery, and so on. Lead-acid battery is good for it has a high voltage, long duration, low cost, technical maturity and discharges easily, but has a low density in energy. Fuel battery often refers to alkaline cell. It has small size, long duration, high efficiency and no pollution. However, in general, this kind of battery is still under-developed.
3) Positioning and Route-designing
At present, positioning and environment model building techniques are not fully developed, so robot cleaner mainly works by random working method and partial route-covering method. Random working method is based on this presumption: provided with sufficient time, robot cleaner can cover all areas of its working environment. Obviously, this method is quite low in efficiency. By contrast, by partial route-covering method, robot cleaner covers automatically route in part without complete environment map and overall positioning capacity. This method attaches less accuracy to positioning capacity and environment model building, but it could only cover a small percentage of cleaning floor.
Robotic route-designing research began in 1970s, and until now it is still developing. Robot cleaner gathers the information detected by its sensors, figures out a bump-free route from starting point to target point, and covers fully all routes in cleaning area. Based on different working conditions, the research includes static structural environment, dynamic fixed and dynamic non-fixed environment. According to different means of gathering information, it is subdivided into model-based route-design and sensor-based route design.
To sum up, automatic intelligent robot cleaner has a favorable prospect in market. Although much progress has been made and this cleaner has been put into market, certain problems still need to be solved, like dissatisfactory self-autonomy and working efficiency. So, techniques like sensor technique, positioning technique and environment model building technique must be further developed. Based on this development, automatic robot cleaner in future will turn out to be highly intelligent, multi-functional and low in cost.