The goal of Seeker is to look around for human beings, drive towards the first it sees and then try to follow that person. Seeker locates humans by using a Passive Infrared (PIR) sensor. This sensor is capable of detecting the heat signature of a human being. It is mounted inside the white cone on the sensor unit at the front of the robot. The white cone holds a freshnell lens to focus the infrared (heat) radiation on the sensor element. The sensor unit also holds tree SHARP GP2D02 infrared distance measurement units. These sensors take over when Seeker gets close to the person it wants to follow. This cannot be done with the PIR sensor because it is not accurate and directional enough at close range. The sensors of Seeker are mounted on a pan/tilt unit. This enables Seeker to look around and point its sensors at any object of interest in its field of view. The drive train of Seeker is the same as that of Roamer and Wallie. It consists of two propelled front wheels and a castor wheel at the back, enabling the bot to navigate the world by using differential steering. The brain of seeker is an ATMEL AVR 90S8535 microcontroller. It is programmed in C using the AVR port of the linux GCC C-compiler. The procedure to locate and follow humans is as follows: At powerup, Seeker starts to turn on the spot. When it detects a heat signature, it drives towards it. When the heat signature is lost during the approach of the target, it starts turning in a circle again to relocate the heat signature. When Seeker gets close enough to the target, the infrared distance measurement sensors take over. In order to follow the target, the distance measured by the left sensor is compared to that of the right sensor (the third sensor is not used right now). If the left sensor measures a greater distance than the right sensor, it concludes the target is located on its right side. If its the other way around, it assumes the target is on the left. It will then move its sensor head in the direction of the target. The motor controller of Seeker is programmed to drive in the direction the sensor head is looking, and therefore the whole robot will start following the target. If seeker gets close to the target he will stop. If the person being followed starts to move towards Seeker he will start to drive backwards to avoid being stepped on. If Seeker loses the target he will start looking for a new heat signature. On my website: http://members.home.nl/hakingma/ you can also find a 2 movies of seeker in action, together with a description of my other three bots. Email: hakingma@yahoo.com