Basic Autonomous Kit for Sphero RVR Assembly Guide

Contributors: Pearce, Ell C
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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.