Basic Autonomous Kit for Sphero RVR Assembly Guide

Pages
Contributors: Pearce, Ell C
Favorited Favorite 1

Introduction

The SparkFun Basic Autonomous Kit for Sphero RVR is an expansion set of sensors to the Sphero RVR platform and is a great way to start driving the Sphero RVR, either remotely or autonomously. The pan-tilt camera provides an excellent base for a video streaming interface while the GPS module provides accurate data for navigation. The Raspberry Pi Zero runs your programming and passes the information to the RVR. Setup is fairly simple but there are a few confusing spots. This tutorial will go over how to properly assemble the kit on the mounting plate provided with the RVR. While we feel it's the best way to set this up, it's not necessarily the only way, so feel free to experiment with different configurations.

SparkFun Basic Autonomous Kit for Sphero RVR

KIT-15302

Required Materials

To follow along with this tutorial, you will really only need a phillips-head screwdriver. We have quite a few to choose from - but our Pocket Screwdriver Set is a great option.

Tool Kit - Screwdriver and Bit Set

Tool Kit - Screwdriver and Bit Set

TOL-10865
$10.95
7
Pocket Screwdriver Set

Pocket Screwdriver Set

TOL-12891
$4.50
5
iFixit Essential Electronics Toolkit

iFixit Essential Electronics Toolkit

TOL-15256
$26.95
1

Electric Hobby Screwdriver Set

TOL-15548
Retired

Before We Begin

If you haven't already, start charging the RVR battery. It takes a while to charge, so now would be a good time to get it going.

Pan Tilt Mechanism

Note: Before assembling the pan-tilt mechanism, it is recommended that users follow the instructions for the servo pre-alignment in the getting started guide to avoid issues later.

Assembling the pan-tilt rig is by far the most involved part of this tutorial. Take your time and read the instructions carefully. Be mindful of the materials you are working with as well - using too much torque or force when tightening screws or fitting parts together can result in broken parts. On a final note, take extra care to make sure the servos are aligned correctly when mounting them.

Here are the parts of the pan-tilt rig that come in this kit. You won't be needing the servo horns that come packaged with the servo motors, just the ones that come packaged separately. You will also not need the base plate that comes with the pan-tilt framework package.

Pan-Tilt mechanism parts

Click the image for a closer look.

First, identify the larger self-tapping screws. These will be used for assembling the bottom part of the mechanism or the "Pan" part.

Self-tapping Screws

Find the Pan Brackets - these are the two brackets that sandwich together. Place one of the servos in the center and connect the two brackets. Take note of the orientation of the servo in the brackets below as it's important.

Brackets around Servo

Here are the brackets together. Try to make sure the servo is centered.

Brackets fitted together around servo

Take the larger self-tapping screws and affix the two brackets together like in the image below. Take extra care not to over-torque the screws and damage the plastic.

Side view of bracket with screw

You'll now need the single arm servo horn with 5 holes, as shown in the image below. If, for some reason, the single arm servo with 5 holes was not included in the kit, you have two options. You can either contact Customer Service to have them send you a part, or you can modify one of the 6-hole servo horns that were packaged separately. If you are shortening the 6 hole horn, start by clipping off one hole and checking to see if it fits the mold on the tilt bracket. Be careful when clipping and make sure that you do not clip off too much of the horn.

5 hole single-arm horn on the bracket

Install the single arm servo horn as shown below. You'll need two of the small self-tapping screws to affix it to the mechanism.

Installation of single-arm horn

Next, you'll need the second servo motor and the Tilt Bracket.

Tilt bracket with servo next to it

The image below shows the relative orientation of these two pieces:

Servo installed on tilt bracket

Now, find the longest machine screws in the bag, as shown below. You may find that there are more of these than you need.

Machine screws

Thread these screws through the stand off wings on the servo motor and into the last piece of the mechanism. You can use nuts for these if you like, but I've found it to be unnecessary as they thread into the mechanism quite snugly without the nut.

Screws affixing servo to tilt bracket

Now connect the two major pieces of the assembly together. The image below shows the orientation of these two parts. You may need to assemble and disassemble these two parts a couple of times to find the right rotational position of the servo motor so that the tilting portion has its full range of motion. Do this by connecting the two parts and carefully turning the "Tilt" servo back and forth until it's able to get the most unobstructed range while the mid-point of this range falls when the two servos are perpendicular to each other.

Pan and tilt mechanisms lined up next to each other

Here's an image of what it should look like with the two mechanisms attached.

Pan and tilt mechanisms attached

Sometimes the pan and tilt parts won't line up evenly. if this is the case, add a nut (provided in the bag) between the servo and the plastic part of the tilt mechanism as shown below.

Standoff screw between the servo and bracket for the tilt mechanism

Take the final screw that you identified above as a horn attaching screw and use it to secure the horn to the servo motor. You do NOT need much torque here - be very gentle!

Affixing the pan bracket to the tilt bracket

Congratulations! You've finished the most difficult part of this build. The rest should be a breeze! Put the pan-tilt mechanism to the side, we'll connect it to the cover plate of the RVR at a later time in the build.

Standoffs and Mounting for the Pi Zero

The Pi Zero W mounts to the cover plate with two 4-40 nuts. It uses two of the holes made for the full Raspberry Pi footprint.

Raspberry Pi Zero and mounting hardware

This keeps the camera connector within reach of the pan-tilt rig, yet not in a position to tangle itself.

First, we'll affix the 1/2 inch screws to the Raspberry Pi Zero with two 4-40 nuts. This will provide a small standoff from the RVR cover plate which allows room for the pins on the bottom side of the Raspberry Pi Zero.

Raspberry Pi Zero with standoff nuts

From there, we'll affix the Pi Zero to the RVR cover plate with a second set of nuts.

Raspberry Pi Zero mounted on cover plate for the RVR

Mounting the GPS Board

The GPS Qwiic board mounts next to the Pi Zero W. For the Qwiic cable to work, the Qwiic connectors need to be facing front and back in relation to the RVR. We'll use 2 of the 1/4 inch screws and 2 of the 4-40 nuts.

GPS board mounted to the cover plate along with the Raspberry Pi Zero

Mounting Pan - Tilt Camera to the Cover Plate

The pan-tilt rig will mount to the forward-most servo footprint on the cover plate.

Servo footprint on RVR cover plate

The horn goes under the cover plate. Use two of the self-tapping screws included with the horn to mount the horn to the plate from the top (see pictures below) using the holes that line up.

Servo horn positioning

Mounting the horn to the bottom of the plate using screws

It’s important that the rig is mounted so that the middle of the servo travel faces forward. This will take some trial and error, but you want the servo to be able to move an equal amount in either direction when facing directly forward (it’s okay to move the servo when it isn’t powered, just don’t force it).

Fully affixed horn as shown from the bottom of the cover plate

When mounted, it should look similar to this.

Pan-tilt rig mounted to RVR cover plate

Plugging in the pHAT and Cables

The Servo pHAT is the interface for both the pan-tilt rig and the Qwiic sensors. The pHAT plugs in so it’s stacked directly above the Pi Zero.

Servo pHAT plugged into the GPIO header of the Raspberry Pi Zero

The Qwiic cable that connects the GPS Board to the Servo HAT runs underneath the cover plate as shown below. It’s best to plug this in at this step as the pan-tilt cables will impede it later.

GPS module plugged into the Servo pHAT with a Qwiic cable

The servo cables for the pan-tilt rig will run underneath the mounting plate, under the board and pop out on the opposite side. The bottom servo plugs into ROW 0 and the top servo into ROW 1.

Row 0 and Row 1 highlighted

The brown wires should be on the pins closest to GPS board. See the image below:

Pan-tilt servos plugged into the Servo pHAT

Click the image for a closer look.

You can also run these cables underneath the cover plate but be sure it won't impede the movement of the pan-tilt mechanism.

Plugging in the Camera

You'll need to mount the Raspberry Pi Camera to the pan-tilt mechanism using the included square of double sided tape. However, I recommend you plug in the camera to the ribbon cable before securing the camera to the tape square.

To connect the ribbon cable, you'll need to carefully slide the flexible ribbon cable connector's locking tab out. The locking tab slides out parallel to the board so you'll need to push each side of the tab with your fingernails. The image below highlights where you would need to place your fingernails to slide the tab out.

Highlighted camera connector tabs

Once the locking tab is out, you can insert the camera connector into the slot. Face the camera's exposed contacts toward the PCB in order to make a connection with the connector's pins. Then insert the cable until it is firmly into the connector. Care must be taken to ensure that the ribbon cable does not have any sharp bends when installing the camera.

Inserting the camera connector ribbon into the camera connector slot

When ready, carefully slide the tab back into the locking position using your fingernails.

Gently push the locking mechanism back into place

Now you can mount the Raspberry Pi Camera to the pan-tilt mechanism. Make sure the correct side is facing up. Once mounted, it should look something like what we see here:

Mounting the Raspberry Pi Camera onto the Pan-tilt mechanism

You'll also need to connect the camera ribbon cable to the Pi Zero W. The locking mechanism for the cable is exactly the same as the one on the camera breakout. Again, make sure the contacts of the ribbon are faced correctly. This part can be tricky - take your time and make sure there are no sharp bends in the cable.

Camera cable plugged into the Camera and Raspberry Pi Zero

Plugging the System into the RVR

You've built the entire system! Now it's time to connect it to the RVR. Gently clip the RVR Cover Plate into place. We'll then connect the 4 pin Ribbon Cable from the four pin connector on the Servo pHAT to the UART Connector on the RVR.

4 pin cable plugged into the RVR UART connector and the Servo pHAT

Congratulations! You've completed the kit and are ready to start coding!

Troubleshooting

Resources and Going Further

So you've got this amazing looking robot. Now what? Time to program it! Head on over to the Getting Started with the Autonomous Kit for the Sphero RVR Tutorial to get coding.

Getting Started with the Autonomous Kit for the Sphero RVR

December 13, 2019

Want to get started in robotics? Look no further than the SparkFun autonomous kit for the Sphero RVR! Whether you purchased the Basic or Advanced kit, this tutorial will get you rolling...

Need more information on the components included in this kit? We've got it!

Need more inspiration? Check out some of these other great SparkFun tutorials!

SparkFun Line Follower Array Hookup Guide

Learn how to connect the RedBot Line-Following Sensor Bar to an Arduino-type microcontroller. Use the example sketches to read data from the bar, and try out a simple line-following algorithm.

ReconBot with the Tessel 2

Build a robot with the Tessel 2 that you can control from a browser on your phone or laptop.

LIDAR-Lite v3 Hookup Guide

A tutorial for connecting the Garmin LIDAR-Lite v3 or the LIDAR-Lite v3HP to an Arduino to measure distance.

Qwiic Joystick Hookup Guide

Looking for an easy way to implement a joystick to your next Arduino or Raspberry Pi project? This hookup guide will walk you through using the Qwiic Joystick with the Arduino IDE on a RedBoard Qwiic and in Python on a Raspberry Pi.