Design Description

        After design trade studies, we know using powerful fans to provide adhesion is suitable to pass the designed tasks in this course. However, there is a fatal downside that fans consume too much power to avoid a tether.  Some companies have already put their electronic window washer on the market. ECOVACS® has its own series of window cleaning robots called Winbot, but the Winbot is design to be used indoor. It can’t work without the tether as its power source. Our goal is to make a truly scalable and working window washer to wash the outside of windows for human. Therefore, we decided to use suction cups to provide adhesion instead, and to make powering the robot by batteries possible. Below are the analysis of our design and decisions of chosen parts.

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Adhesion

            For our adhesion principle we chose a strategy of multiple suction cups.  Adhesion is accomplished with two suction cups.  At any given time, one or both of the cups are attached to the window.  Suction will be created by applying a vacuum to the inside of the cup.  The power of the adhesion will be a factor of the vacuum pressure and the contact area of the cup.  Sealing the cups will also be crucial to adhesion.

 

 

Locomotion

The locomotion of the robot consists of body rotation, cup transfer and barrier crossing.  To move about the window, the robot will rotate its body around a cup.  Once a desired position is achieved the robot will adhere to the other cup.  This will be aided by linear actuation of the cups.  For barrier crossing, the robot will push its body away from the window and step each leg over the barrier in turn. 

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Cleaning

            The concept of cleaning is simple. The robot needs to have a cleaning platform that contains cleaning solutions to wipe out the marks. The cleaning system must be strong enough to clean the marks at one movement each time so the cleaning time can be optimal.

            The cleaning system must also be flexible enough so that both sides of the robot can be cleaned.

 

 

Sensing and Motion Planning

The concept of the motion planning of the robot is pretty straightforward. The robot basically traverses the window by doing rotations and transitions according to its position and readings from sensors. Servos are responsible for rotations. And transition can be done by sending a proper sequence of commands to linear actuators and valves.

Since the main movement of the robot is to rotate, IMU is extremely useful to gain information about its direction of rotation and angular position. On the other hand, ultrasonic sensors provide the robot with information about how far the robot is from surrounding obstacles. The robot can then rotate to correct angular positions and change its moving pattern when detecting an obstacle.

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Controller

Due to the compatibility with the IMU and ultrasonic sensors. Arduino Uno is chosen to control the robot. Also, Arduino Uno has enough pins for the motors and sensors in the robot.

 

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Power

            The power that the electrical components consume is low enough that we chose to use a standard 12V batteries to power our robot. We also purchased a 12v to 5v converter to power the Arduino, sensors, and servos.