Memory
is where living beings store and retrieve the information about their
surroundings with respect to time and with respect to space. Birds,
animals and human being all have memory. With the help of the memory,
the living beings get the ability to “collect” and “recollect”.
The memory can be classified into different types: Sensory Memory,
Short Term Memory and Long Term Memory. The purpose of this article
is not to go into details of memory, however the purpose is to
reflect upon the questions: Why do robots need memory? What is the
format of robot's memory? How much memory is required for a robot?
As
we discussed in the first post (Robot – A machine with life), human
being applies senses to the robot. These senses produce a lot of
information. Consider an example of a Color Sensor. It collects
information regarding the color of the object, based on the light
intensity reflected from the object. An Ultrasonic Sensor produces
the information about the distance at which an object is located.
Depending upon the robotic project, we need to store this
information. For example: 1. In a project where we have to find a
shortest path towards a destination, the robot has to recollect the
location of obstacles and find its shortest path through them. For
this project, we have to store the tentative location of objects into
the memory. 2. To solve a line maze, the robot has to recollect the
location of turns (left, right, U), avoid the extra/redundant turns
to find an exit thought the maze.
The
purpose of memory can be found in the figure given below.
To
elaborate upon the above diagram, lets consider an example of Line
Maze Solver project where the maze consists of black lines on a
white surface. There are light sensors attached to the robot. The
light sensors produces the data about black, white and gray
conditions while steering along a line. The information about
different conditions is fed into a computer program. The program
processes it and helps the robot steer along the line by driving the
motors. While steering, the robot encounters turns (identified by the
motor readings), the information about which is stored into the
memory. The robot uses this information to create a map of the maze.
Using this map, the robot then finds a shortest path along the maze
towards the destination.
Robots
memory is semiconductor memory, which stores the information in bits
and bytes format. You will wonder how much of memory should a human
being apply to robot? When it comes to Lego robots, it contains few
Kilo Bytes (KBs) of memory. Industrial robots may require Giga Bytes
(GBs) of memory. There are three kinds of semiconductor memory: Read
Only Memory (ROM), Ramdom Access Memory (RAM) and Flash memory. RAM
refers to the memory to which the processor can read from or write
to. It loses data when power is off. ROM refers to a memory where a
processor can read from, but it can not write to it or modify it. ROM
is permanent. ROM chips contain special instructions for the
processor. The information does not get erased when power is off. The
processor can access information stored on a ROM chip whenever it
needs to. Flash memory is a special type of memory that works like
both RAM and ROM. You can write information to flash memory but that
information isn’t erased when the power is off, like it is with
ROM.
Hey
there, looks like memory is an essential and important part of a
robot, isn't it?
