Results           

    Our bot was satisfactorily able to navigate and avoid obstacles.

    Obstacle detection worked fairly accurately using the Sharp Sensor. Issues with the edge of bot colliding with an object that it had just avoided were fixed in the software AI. These issues arose since the Sharp sensor was mounted in the center on the bot and had a limited field of view.

    The stepper motors worked satisfactorily. Using a 12 V external power supply we were able to provide them with enough power to steer the bot.

    Using black tape to gag the sensor, we were able to cut down its receptivity and create tunnel-vision. Using four such sensors, one for each direction, we had a mechanism of tracking an IR beam. This knowledge would enable the robot to choose the direction of motion. The accuracy of the sensors is very good at ranges of two-five feet. At closer distances, since two sensors are at 45 degrees to the target, it becomes more difficult to choose one direction. This is resolved by the AI in the software. 

We went through ten days of pain in trying out different variations which would succeed but to no avail. A big stumbling block was the lack of adequate experience in analog design, leading to over-dependence on Professor Land for trouble-shooting and new ideas. However, after this period, we knew what we wanted but also realised the enormity of the task. Essentially, design of an IR receiver module was a project itself. Here’s some sound advice: if you know what you want, look around in catalogues and on the internet for cheap parts which will do the job and contact the vendor and request for samples.

We were overjoyed when we first tested the TSOP1138 because it was powerful enough to pick up beams from more then 20 feet away. Ironically, and perhaps comically, we now faced the opposite problem. Earlier, we had laboured to get adequate gain. Now we had too much receptivity. It was proving to be extremely difficult to restrict the sensor’s vision to a particular direction. It was modeled on a real world IR sensor designed to get the input at all costs, which means if there was no line of sight between remote control and sensor, it would still receive the beams reflected by surrounding objects giving it a 360 degrees field of view. We tried all sorts of tricks, wrapping it with layers of cardboard, cupping it with our hands but to no avail. Using layers of aluminium foil worked but it would often short the Vcc connection to the other pins. It is easy to see how Electrical Engineering is EE (electrifyingly entertaining).

            Learning how to beg, scavenge, and nag is a big part of this course. You have a strict limit on your budget, and you have to be very resourceful.