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Gidget The Gigapod User Guide

From Vorpal Robotics Wiki

Introduction

Gidget the Gigapod works identically to Vorpal the Hexapod. It has all the same dance and walking modes, programming capabilities, etc. So the Vorpal hexapod user guide also applies to Gidget the Gigapod.

The same type of cautions regarding damage to the servo motors should be observed with Gidget the Gigapod.

Experimental

Please note that the Gigapod is considered an experimental project at this time. Fewer than 10 of them are known to have been built worldwide right now, so this project is less refined and less tested than our other projects.

As such, this project is only appropriate for experienced robotics hobbyists who are aware of safe handling procedures for powerful batteries and motors. If you do not have that level of experience, you should start with smaller, more refined robotics projects first, such as our Vorpal Hexapod.

Safety Warnings: Do not touch the Gigapod while operation, remove battery before picking up

In addition to all the safety warnings for our smaller hexapod projects, in addition this project has an additional warning. The motors are extremely powerful on this hexapod and if fingers got in the way of the legs they could be broken, crushed, or even amputated. For this reason, extreme caution should be used when operating the hexapod. No spectator should be allowed near the Gigapod. The Gigapod should always be powered off and battery removed before picking up. (Not just turned off! Battery must be removed completely to guard against accidentally hitting the ON switch while carrying).

The safety stickers provided with our kits (or which you can print yourself from the Assembly Guide) are not an optional item. They should be installed on the robot body such that they can be seen from any side of the robot, in order to warn onlookers.

Recommended Battery

The recommended battery to run the gigapod's motors is a 7-cell NIMH (8.4 volts) with 4000 to 5000 mAh capacity. Going much below 4000 mAh will result in runtime that is too low, going much above 5000 mAh will put too much weight strain on the robot.

The battery we typically use in demonstrations is this one: BatterySpace 4200 mAH 8.4V NIMH with the 14 gauge wire option, and we solder on an XT60 male connector in-house. You will get about 30 minutes of run time. Be extremely cautious when soldering a connector on a powerful battery. There are youtube videos that show the proper way to do it.

The robot also needs a 9v battery (to run the electronics), and the gamepad needs another 9v battery. We recommend rechargeable NIMH or LI-ON for this purpose.

Note on Battery Life

Because of the way things scale as you move up in size, Gidget does not have as long battery life as the smaller hexapods. The recommended battery will provide about 30 minutes of use. Using a battery that is larger may stress the servo motors too much due to weight of the batteries. This means that if you plan on using Gidget for public demonstrations that last much more than 30 minutes, you should have several spare batteries charged and ready to swap in.

As with our other hexapod projects, as soon as Gidget struggles to stand and move, you should discontinue use and swap in new batteries. Running on low batteries may permanently damage the batteries and overheat and damage the servos (which are very expensive).

Some Motions May Not Work Well

Some dance moves and walking modes may not work as well for this large hexapod as they do with our smaller versions. It's best to avoid dance modes that seem to struggle and strain. We may change the Gigapod software in the future to disable these modes entirely.

Some of the motions that are known to have trouble are: Teeter Totter dance modes, Belly Crawl walking mode.

More may be added to this list over time as we continue refining and testing the project.

Note on Reflashing the Robot Code

Right now the software is the same for all three sizes of hexapod (Vorpal the Hexapod, Max the Megapod, Gidget the Gigapod). The only difference is a single timing parameter that should be set for the larger robots. If you reflash the robot code, make sure you change the line:

#define HEXSIZE 0

To this for the Megapod:

#define HEXSIZE 1

And to this for the Gigapod:

#define HEXSIZE 2

This changes how fast commands are sent to the servo motors. In general, larger motors require a bit more time to reach their commanded position. Failing to make this change may result in walking modes not functioning as expected, because the servo move commands come in too fast for the larger servo motors.