[...]... distributed processing is the Horseshoe game running on the Gantry The controller on the main frame controls the motors and interacts with the operator The other processor is on the x-frame It deals with the camera sensor when scanning the playing board to register the positions of the pieces The logic of the game is performed by the controller on the main frame The Gantry robot (Project 6.5, p 297)... radiation The programmed behaviour is designed so as to keep the amount of reflected IR constant In this way it keeps the robot at a constant distance from the wall When the robot veers toward the wall, the amount of reflected IR increases The sensor detects this increase The program responds to this increase by steering the robot to the right, making it veer away from the wall The reverse happens as the robot. .. Part 1 Robot behaviour: what they can do Part 2 Robot mechanics: structures, materials, ready-made parts, tools Part 3 Robot electronics: components, sensors, actuators, and the circuits to drive them Parts 4 and 5 The PIC microcontrollers: How they interface to the robot electronics and how to program them to control the robot s actions 4 Making a Robot This is a cookbook There is no need to read Parts... robot veers away to the right The usual function of negative feedback is to hold things constant It produces stability There is also positive feedback In the case of the wall-following robot described above, suppose that by mistake the output lines to the motors were swapped Then the slightest deviation from the correct robot wall distance would cause dramatic results The robot would either veer permanently... from some robotics suppliers Unfortunately, their precision is low but they are fun to experiment with The most practical solution is a gantry, described in the next section 15 The Robot Builder's Cookbook Activities of gantry robots A gantry robot operates over a clearly defined rectangular area It picks up objects from any point in the area and sets them down at another point in the area The tool... button to download the assembled program into the PIC The assembler software converts it into machine code and transfers it to the PIC's program memory Once the program is in the PIC it stays there for years (or until you change it) Plug the PIC into its socket in the robot circuit and test it for real 8 Robot Behaviour Robot Behaviour Activities of mobile robots 10 Activities of gantry robots 16 Feedback... and the other for steering Detecting and responding to light Sight is probably the most important of all human senses The same applies to mobile robots Some can detect a lamp which is several metres distant, and aim themselves towards it Or maybe they will go in the opposite direction, to end up in the safety of a dark corner The Quester robot homes on a source of light 11 The Robot Builder's Cookbook. .. browse them to pick out any items of interest Dip into these parts and gradually put together the final specification Controlling the robot The first robots (they were called automatons in those days) were purely mechanical, driven by clockwork or steam power The arrival of electronics greatly increased the scope of what robots could be made to do Modern concepts of robotics began to emerge The big... programming, the machine code files are available on the Companion Site (opposite p 1) Download them into a PC, then use a programming deck to copy them to the PIC 7 The Robot Builder’s Cookbook Simulating the PIC The software supplied with a programming deck usually includes its own assembler and, as already mentioned, may have a BASIC or C compiler built in to it On the computer screen, type in the program... the 20-pin Atmel AT90S1200, and the 28-pin PIC16F87 The data sheet in the background was down-loaded free from the Microchip site on the World Wide Web 5 The Robot Builder’s Cookbook There are several manufacturers of microcontrollers (or controllers, as we will call them in future), but the PIC controllers made by Microchip Technology, Inc seem to be the most popular in the hobby field (and in many professional .