Ingoshu
From HBRC WIki
Contents |
Overview
Ingoshu is a six-legged walker built by Rose Mills and Michael Cipriano. It was our first robot together and we built him using the book Insectronics, though we scaled up the size of the robot a little.
Brains
Ingoshu was first built with a Basic Stamp microcontroller, though controlling all the servos (3 total) proved a little too tough for the Stamp that we had, which gave his gait a sort of tap dancing look to it. We then used a PIC microcontroller (18F4680).
Brawn
Ingoshu's body is made using cut aluminum stock (using a Dremel tool initially until we bought a saw). He is propelled by 3 hobby servos, though we did get a slightly tougher servo for the middle legs since they had to lift the whole body. We also custom made his shoes using a prototype shoe that we made with Sculpy Clay, then created a mold using a RTV Silicone mixture. We then created 4 identical shoes using a RTV plastic mixture and painted them with model paint.
Sensors
Ingoshu has microswitches on his four corner feet. The microswitches allow Ingoshu to detect if he a foot is contacting the ground, which gives him the ability to know when he sets a foot down and there is no surface. This allows him to complete phase I of the table top challenge, to walk across a table and back again, without falling off.
Intelligence
We coded Ingoshu's behavior using Microchips MPLAB suite of tools and the C language. Ingoshu is a table bot and can walk around a table without falling off.
Lessons Learned
Lesson #1: Locking Nuts & Washers
Use lock-nuts or lock-washers to prevent the screws and nuts from coming loose. One of the first few times Ingoshu was walking around, he took about 3 steps and then fell apart!
Lesson #2: Processing Power
The Basic Stamp has limitations (for the capabilities we wanted anyway). There aren't really if then statements and loops like there are in C, which was a bit confusing for us c-programmers at first. We worked around it and then were eventually limited because the stamp had to send signals to multiple servos at a time while also reading the button feet, and it didn't do this quite fast enough, resulting in the "tap dance" walk which turned out to be a cute little side effect.
Lesson #3: PCBs
- When creating your own PCB by hand, make sure you account for all parts and the layout of the PCB, and pay very close attention to the orientation when you begin adding the parts. I accidentally mirrored some of the parts and had to change the layout midstream.
- If you do change the layout midstream- document it! Our result was a confusing circuit board. The simpler you keep the wiring, the better.
- It is better to have 1 large board or 2 small boards than try to squeeze all through-hole components on one small PCB.
Ingoshu now has a loose or shorted connection and it is near impossible to locate it!
Lesson #4: Connectors
If you use non-latching connectors (i.e. 0.001" headers with non-latching counterparts), make sure they are as parallel to the ground as possible so that the connectors do not fall off during walking/motion.
Lesson #5: Servo Torque
Torque must be taken into account when lifting 'heavy' objects. The first servo used to tilt Ingoshu's body burned out pretty quickly, then we realized we needed a heavier duty/higher torque servo for more reliability and so Ingoshu could lift his feet higher.
