This time I'd like to write about something different from walking robots and brushless actuators - my robotic projects from the past. These projects were a very important part of my engineering carrer and I feel obliged to at least mention them here and leave a short note on the most important ones.
I started my hobby by building simple sumo robots for competitions that took place regularly in my country and in many other places all over the world. The sumo robots are standardized i.e. the each category has a certain mass and dimensions restriction that the robot has to fulfil in order to participate. The goal is simple - push the opponent out of the dohyo (this is the name used for describing the ring the robots are fighting on). Each event's rules are different, but generally the robots should not intentionally destroy each other, directly interfere opponents sensor readings, emit gasses or drop any parts/substances on the ring (so it is not the battlebots kind of thing).
I used to build robots in two categories - mini and nanosumo. This entry is dedicated to my minisumo robots.
Haker
Haker was my first minisumo robot created back in 2011/2012. The frame was soldered from manually cut laminate pieces. The motors were just two big servos and the wheels were made out of nutella jar caps with adhesive pads glued on their perimeters. The robot was equipped with two flaps used to lift the opponent (or trick its white line sensors, so that it backs off and falls of the ring).
Robot's structure with flaps in the down position
Robot's structure with flaps up position
The controller board was based on through-hole elements and home-etched laminate. Looking at it today I'm amazed it did work back then :) The opponent sensors were homemade IR sensors with two infrared leds modulated with 36Khz PWM signal and a TSOP receiver. It was essential to cover the leds with black tape, so that only the reflected light would trigger the receiver. White line sensors were just tcrt5000 infrared reflective sensors mounted in each of robot corners.
Main controller board - the microcontroller is atmega8, and the H-bridge is LM298
Two opponent infrared sensors - each of them was equipped with a separate Attiny13 microcontroller
Haker with onboard electronics
Eventually the robot was equipped with flags that meant to distract the opponent's distance sensors.
Finished Haker robot
And a short video of robot operation:
Haker 2
Haker 2 was the second robot that I created. It came with a few new solutions, especially new motor unit based on worm gears, and integrated proximity sensors. The goal was to keep the center of gravity as low as possible, and reduce robot's height in comparison to previous iteration. The base of the robot consisted of a home-etched PCB board with steel case around it. The PCB had an extension for mounting the gearbox and the motors.
First revision of the Haker 2 control PCB
Second revision of the PCB
The gearbox was built with available components from disassembled devices and toys. Back then I wasn't particulary worried about the durability of these plastic gears :) Of course, in the end, it turned out to be a poor drivetrain design for minisumo robot, as the gears were wearing out quickly during battles.
The gearbox without motors
The wheels were initially made of two pieces of PVC tube wrapped with small rubber bands, but eventually the tires were casted from soft silicone for improved adhesion.
The case was made of 1.5 mm metal sheet, that was cut in the desired shapes. Some of the pieces were soldered together in order to form a solid shel
Back then I even tried to make my own soldermask using a special high-temperature paint. It was rather soft compared to real soldermask layer, but it protected the PCB from random short-circuits between traces.
PCB with homemade soldermask
Finished robot
And a "battle" video with it's older brother:
Family photo
Haker 3
Haker 3 was the third and last of "Haker" robots series. The biggest difference, compared to earlier versions, were the pololu micro motors (which were used in most minisumo robots back then). These motors were really small and could easily fit inside two PCV tubes serving as rims. Again the robot consisted of a big PCB board:
The PCB was the base to which all other components were mounted. I remember I found this "powerful" double channel H-bridge MC33932, which I was very excited about as other robots were based on TB6612, which used to fail from time to time. White line sensors (KTIR0711S) were located in the front part of the PCB, near the edge.
The cover was made entirely out of laminate pieces (that weren't aligned very well...):
The device on top of the battery is actually a start module that was used to simultaneously turn on both robots, instead the "five second rule" (the robot was triggered by hand and had to wait "exactly" five seconds before starting). With the start modules it wasn't possible to cheat by launching the robot earlier than the opponent.
The only videos I have are when the robot wasn't equipped with laminate shields:
This entry is getting too long, so I will stop for now and divide the history of my minisumo robots into two parts. Till now I've introduced three of five minisumo robots that I created. These first three did not win any competitions, but things have changed, when it comes to the next two robots ;)
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