What is Marty The Robot?

Marty is a bipedal (i.e. two legged) walking robot and is about 25 cm tall. All of Marty’s parts are hard plastic, and it comes either as a kit or fully assembled. One or two parts have threaded inserts in them to make it a bit easier to build. Everything you need to build the robot comes with the kit. Marty gets its power from a special USB cable which is able to convert 5V to the 9V needed to charge the battery. There are even a whole bunch of stickers that you can use to customise it.

Marty is an open source project. If you have access to a 3D printer you can easily make your own, as the 3D design files for all the plastic parts are available. Marty’s main controller board, Rick, and all the nuts, bolts and screws needed to build it are available from its maker here.

How does Marty work?

Marty’s brain, which is called Rick, is a powerful ARM Cortex M4 processor. Rick’s computer has 512KB of RAM for storing programs and data and a 128K ROM for Marty’s low level firmware. There are also lots of inputs and outputs for all the servos and external sensors that Marty uses.

Marty’s legs need three servos¬† each to act as thigh, knee and ankle joints. Marty’s walk has a sort of twisting, striding action that makes it quite stable. The robot’s arms, which rotate around, need one servo each. Another servo rotates Marty’s eyebrows, which gives the robot a degree of expression such as being surprised or angry!

A bump sensor on Marty’s toe gives it a sense of touch to kick a ball. Attach one to the bottom of Marty’s foot, and it is able to detect the edge of a table so that it doesn’t fall off. In addition, my kit also included an optical distance sensor.

Programming

It is possible to program Marty using Scratch 3, from an iPad or computer. If you have a PC, Chromebook or Mac, you can add an extension called Scratch Link to Scratch. With Scratch Link, you can turn a BBC MicroBit into a remote control for Marty!

Although programming Marty using Rick is on its own pretty good, it is possible to enhance Marty’s brain power by adding a Raspberry Pi computer. The Raspberry Pi can run ROS, which is a standard Robot Operating System. Using ROS allows the addition of sensors such as a camera, which can be utilised to give Marty a sense of vision. This, combined with the availability of robot simulation software for Marty makes it an incredibly powerful tool.