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Attaching the components to the chassis

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Attaching the components to the chassis

Once you have ensured that all the robot parts fit into the chassis, you need to secure some of the components in place.

Permanent and removable fastenings

Some types of fastening might be preferable to others, depending on the material of the robot chassis and the component that is being secured.

You may not want to use permanent fastenings such as adhesive putty or glue when you are making the prototype chassis, if you intend to remove the components later. In this instance, a fastening that is easier to remove may be better, such as tape, cable ties, or Velcro-type strips. Once you are confident that you will not have to take things apart, using a permanent fastening might be desirable, to keep the components secured firmly in place.

Screw holes may need to be incorporated into the chassis to attach some components, such as the ball caster. If you are using a material that is fairly durable, like metal or a hard plastic, you can use a threading tool to create threads for the screws. Otherwise, you can use a sharp instrument to make a small hole for the screw to go through.

Securing the components in place

I'm going to be using a cardboard box as my chassis. If you are using a different type of material or container for your chassis, some of these instructions may need to be adjusted to suit your design.

A cardboard box that will be used as the chassis for the robot buggy

  1. The first step is to place your motors into the chassis.

Place your motors inside the box, in roughly the position you would like them to be in. Then use a pen to mark the place where the motors’ axles will need to pass through the walls of the box. Make sure you are giving your wheels enough room to spin around.

The chassis containing the motors and a pen marking where a hole needs to be made for one of the axels of a motor

  1. Make a hole that is big enough for the motors’ axles to fit through.

If your chassis is made of cardboard, use a sharp object (such as a pencil or screwdriver) to carefully poke holes through the sides of the box. For more durable materials, use a threading tool or drill.

  1. You will need to secure the motors firmly to the chassis. If you don't, the motors may move inside the chassis once the wheels are attached and the motors are powered, and this could disturb other components. Tape or cable ties might be best for your prototype, as they are easy to attach and remove if necessary.

The motors secured with cable ties to the chassis

  1. Once the motors are in place you should attach the wheels to the axles.

The chassis with the wheels attached to the motors

  1. Next, you need to attach a ball caster to the front of the chassis to support the robot and act as a third wheel.

The ball caster positioned at the front of the chassis so that the chassis is level with the ground

Start by assembling the ball caster. It is useful to work out where the screw holes for the ball caster should be on the chassis before securing it in place. Place the ball caster face down inside the chassis near the front-centre, and use a pen to mark where the screws need to go. If your chassis is made of cardboard, use a small, sharp instrument to carefully make holes in the places you marked; use a threading tool or drill for more durable materials.

The holes being made for the screw fastening of the ball caster inside the chassis

Most ball casters come with spacers to increase the height. If the chassis dips towards the floor at the front, add spacers to the ball caster until the chassis is level. Otherwise, you can adjust the position of the ball caster forwards or towards the back of the chassis if the buggy is dipping where the wheels are.

  1. If you haven't done so already, place the motor controller, Raspberry Pi, and battery packs for the motorboard and Raspberry Pi inside the chassis.

You won't need to secure these components to the chassis just yet. Remember that you will need to access the Raspberry Pi and parts of the chassis later in the course, to add the ultrasonic distance sensor and line-following sensor.

Make sure there is nothing that could disturb the jumper leads that are connected to the Raspberry Pi, as they can easily come loose.

The motors, motor controller, Raspberry Pi, AA battery holder and USB battery pack inside the chassis

Discussion

Did you have any issues with attaching components to the chassis? If so, what adjustments did you have to make?

What types of fastenings did you use for your robot buggy?

Share your answers and a picture of your robot (hosted using Imgur or another image-hosting platform) in the comments below.