What is a Celtic Maze?

What are the various ways in which you can solve the following maze with an IR based black link follower robot? How can you solve it with the minimum number of sensors possible and the quickest time to reach the end?

• With how many sensors can this maze be solved? I will be using a microcontroller to solve. The maze is you start from the box at the left bottom and reach the top right box. Left Hand Rule or the Right Hand Rule will cause a slight trouble. Is there any other way to do this?

• Answer:

  I am writing this answer with an assumption that the reader has a basic knowledge about http://en.wikipedia.org/wiki/Microcontroller, http://en.wikipedia.org/wiki/Programming, http://playwithrobots.com/make-it-form-scratch/simple-line-follower-robot. If the maze is fixed (i.e. this is the maze which the line follower will encounter every time) then these tips might be helpful: 1. You can hard code the path in which the line follower should follow. In this case the shortest (and easiest) path would be go straight and turn left to reach the end. 2. For this you need to find the nodes. Nodes are the point in which two or three lines intersects. In the above case the Line follower (LF hereafter) should take a left turn in the second node. If the maze is not the same always and if it is random at any point of time then there are three possibilities to reach the end of the maze. 1. Always left 2. Always right 3. Always straight I have learned Always left algorithm from this doc: http://www.pololu.com/file/0J195/line-maze-algorithm.pdf In each cases you can priorities your turns. For example in 'Always left' logic the first priority is given to the left turn. You can choose the second priority for depending upon your maze. If you choose the above maze I would choose the second priority as right turn (considering the extended lines at the edge into account). The same goes for the other two logic. Other than left hand and right hand logic I guess no other technique will be efficient to solve the maze. Coming to your question on number of sensors to be chosen. The optimal number of sensor I would choose is five arranged in the following manner. I will number the sensors in the following way to explain in detail: 2 and 3 sensors are used for following the straight line. The number 1 and 4 are used to detect the node. If the number 1 comes on a black line, left node is detect. If 4 comes on a black line right node is detected. The number 5 sensor is a multi-purpose and it is placed little ahead for a purpose. 1. It is used to follow the straight line. 2. It is used to take right or left turn. Here are the few possibility you would encounter while solving the maze with the above mentioned sensor arrangement. 1. For following straight line: The sensor should be in the above shown arrangement. It is assumed that you are using two motors which have practically different rpm. If it is so the LF can't follow the straight line. It would take a little left or right turn depending upon which motor is moving slow. So if the LF moves little left the sensor arrangement would be: Note that the sensor 5 came to white surface and the sensor 3 came to a black surface. Now you have to take a right turn to bring back the sensor 5 to black and sensor 3 to white. Now from the above explanation you can recreate a scenario if the LF takes little right turn while moving straight. The sensor 5 is also used take extreme right or left or U turn. (U turn is nothing but two extreme right or left turns). Say you want to take a right turn in a node. Now if the LF encounters a right node the sensor arrangement would be like this: The right node is detected when the sensors 3 and 4 comes on black. Now to take a right turn your just have to turn right until the sensor 5 comes on a black line. You don't have to monitor other sensor. Just number 5 is enough. I am leaving the rest (left turn and U turn) to the readers thinking. P.S.: Sorry for my poor drawing skill.