{"id":1647,"date":"2015-12-12T16:34:18","date_gmt":"2015-12-12T20:04:18","guid":{"rendered":"http:\/\/blog.danjoannis.com\/?p=1647"},"modified":"2021-12-18T13:54:47","modified_gmt":"2021-12-18T17:24:47","slug":"steve-new-chassis-3d-printing-fresh-electronics","status":"publish","type":"post","link":"https:\/\/blog.danjoannis.com\/?p=1647","title":{"rendered":"STEVE – New chassis, 3D printing, fresh electronics!"},"content":{"rendered":"

\"IMG_20151122_133544\"<\/a>Plenty has happened since our last post, and most of it can be summarized with the following picture.<\/p>\n

Yup, lots of wires. New body, too. With my 3D printer back in service, cases were printed for the electronics, along with new wheels all around. These new wheels add around an inch of ground clearance, and better off-road traction.<\/p>\n

As well, the first shipment of new parts has arrived: a USB WiFi adapter, an ultrasonic range sensor, H-Bridge motor controller, 9-DOF IMU and a temperature probe.<\/p>\n

There are a lot of really cool developments in this post; let’s dive in.<\/p>\n

<\/p>\n

Chassis<\/h2>\n

\"31O0SVih3CL[1]\"<\/a>By far the most obvious change is STEVE’s body. Before, a Porsche 944 served as the initial test platform. A visit to the thrift store scored a remote control Humvee, with 6-wheel drive.<\/p>\n

It was originally designed as a wall climber, so the first order of business was removing all the fans, duct-work and Styrofoam. The result was a skeleton ready to be re-purposed.<\/p>\n

\"20151106_235827\"<\/a>The biggest difference between the Humvee and the Porsche is the drive train. The Porsche had front steering wheels, while the Humvee is driven like a tank. This forced major changes to the driving control code, since steering now involved slowing down one of the drive motors, rather than turning the front wheels.<\/p>\n

This is good news, though. It is much easier to design a robot that can turn in place, than one which must learn how to complete a 3-point turn. There is a small limitation to this platform, and it is obvious by looking at the product image – the tires are just not big enough. While perfectly comfortable driving along flat walls, these tiny wheels are useless on the ground.<\/p>\n

Is it 3D printer time?<\/p>\n

3D Printing<\/h2>\n

Yes, yes it is.\"Wheel\"<\/a><\/p>\n

The stock wheels just won’t do, so with a bit of 3D modelling and a pair of calipers, new knobby tires were designed. These should be fairly good off-road, and they do reasonably well on floors.<\/p>\n

Four large ones and two smaller ones printed, and STEVE is almost 1.5″ off the floor. Lots of clearance, though it required cutting some plastic from the toy’s shell to make it all fit.<\/p>\n

A few more hours of modelling and printing later, and a few more parts were made.<\/p>\n