SMART WINDORO V1.0: Smart Window Cleaning Robot

From Control Systems Technology Group
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In this article the smart windoro is presented. The smart windoro is the successor of the windoro, the first fully autonomous commercialized window cleaning robot. It adheres to window glass by means of four permanent magnets. This is very different from the conventional mechanism which are mainly based on vacuum suckers. The magnets are placed on the inner and outer side of the glass. The inner unit is responsible for navigation, while the outer unit is responsible for cleaning. In comparison with its successor - the windoro - the smart windoro is very similar but it has some extra features. It has namely a mechanism for cleaning corners of windows, a vertical position control and an autonomous magnetic force control.

At first the article states that the current technologies for window cleaning robot do not meet all the conditions and requirements to be an efficient, safe and fully autonomous window cleaning robot. For example, most of them have an external power line or vacuum pipe line, which is very energy inefficient. The vacuum pipe lines are especially problematic because they impose the risk of falling down.

The successor of the smart windoro, the windoro, consist of two units, each having four permanent magnets. The magnets are much more safe from falling down and allow the windoro to adhere to the glass with no more energy consumption than due to the magnetic forces. Note that both the windoro and the smart windoro are developed for domestic applications.

Unlike the windoro, the inner and outer unit of the smart windoro do not have the round magnets any more. They are now converted into rectangular magnets. Rectangular magnets are more suitable because they increase the magnetic force and reduce the weights by letting the the area of the magnets increase and the thickness decrease. Another addition is the autonomous magnetic force control. This part is required to let the windoro operate on different windows with different thicknesses. The magnetic force on the old windoro had to be controlled manually by lifting the magnet holder. This was the most important technical limitation of the windoro. The new version has a geared motor which can lift the magnet holder and a measurement device that measures the magnetic force. With a feedback loop the measurements of the magnetic forces are compared with a reference signal and the rotating direction of the motor is adapted.

A third addition is the vertical position control, which is of high importance in minimizing energy and time consumption. While moving on a horizontal path on a window, the robot need to keep the optimal vertical position because cleaning areas twice or cleaning them not at all is of course undesirable. Therefore a vertical position estimation unit is mounted to the device. It works like a ball mouse system. The information received from this kind of ball mouse system is translated to the vertical position and combined with the current knowledge of the robot. Additional sensors are added to reduce the error and a control loop is again used to keep track of the vertical displacement.

The last addition is the corner cleaning mechanism. The old windoro had a circular rotating disk, while the new windoro has a rectangular shaped disk performing a back-and-forth motion. This enables the windoro to clean corners of windows properly.

The smart windoro’s performance and movement was assessed in an experimental setup. The robot was adhered to a glass wall and a camera was installed to track the motion of the windoro. The new added vertical position control was verified. The experiments showed that the vertical gap between the horizontal sweeping lines decreased significantly. Hence the vertical position control stabilizes the vertical gap between the horizontal sweeping lines. The corner cleaning mechanism was verified as well. More area was covered with the rectangular cleaning pads and their back-and-forth motion.

It is concluded that the smart windoro is more intelligent, performs better and has a higher efficiency than the old windoro.