Recently, we did a teardown of the iRobot® Braava® 380t Mopping Robot, to understand the different mechanical and manufacturing design elements that help to get you those squeaky-clean floors. Before we got started, we decided to take a step back and evaluate what features would make up a good mopping robot. The two items we narrowed in on were surface contact with the floor and navigation.
What we found were a number of decisions made to keep production costs low.
Here are the features of interest we’re drilling into for this teardown:
1. Mechanical switches
2. Suspension features
3. Manufacturing processes
What we noticed when opening up the enclosure was the focus on simple mechanical switches that support navigation. While the packaging emphasizes the Northstar Navigation Cubes that help wirelessly guide the Braava, internally, many of the motion controls are quite simple. While simple mechanical switches aren’t necessarily bad, it does bring up product lifecycle questions. Considering how many bumps and bruises this machine will take, will one of the mechanical switches fail?
While the Northstar Onboard Navigation system helps to ensure the Braava covers the floor area in a given room, its actual obstacle avoidance is done through a few mechanical switches and sensors. Instead of using expensive Camera Based Navigation or LiDAR technology, the Braava uses mechanical trigger switches and infrared sensors to create a cheap, yet effective, mopping robot.
Overall: Trigger switches and infrared sensors allow for the iRobot Braava to have directional navigation, avoid obstacles, and move backwards if trapped.
The Braava vehicle has three points of contact: two rear wheels and one large surface that acts as a mop. In order to maintain even contact with the floor, two degrees of freedom where added through a mechanical rod-and-bearing and a spring suspension. Instead of adding weight to the product by using thicker material (which increases risk or warp or sink marks) or using a more dense material (which increases cost), they simply added punched metal plates to both the mop attachments and in the main body, to ensure a good amount of force is being applied to the flow.
Overall: iRobot thoughtfully approached the suspension issue. Instead of adding to the weight with additional injection molded material, they simply added metal plates to the mop attachment and inside the main body. Force is consistently applied to keep constant contact with the ground for the Braava to do its thing (clean, mop, and sweep up debris).
Rather than dealing with expensive or complex tooling, the engineers opted to simplify some of the assembly by doing it by hand. We see this in the heat-staked magnets and the glued-on foam barrier for the mop attachment. The main body is made of ABS, which keeps it low-cost. Around the edges, they applied a light texture and foam bumpers to help cover up some of the inevitable scuff marks. To allow for the IR signal to pass from the navigation cube to the receiver onboard the Braava, they assembled a Polycarbonate top via snap hooks. This assembly was not meant to be repaired or taken apart, and we broke every snap fit while prying off the polycarbonate top.
Overall: Simple materials and processes result in a simple, effective, and robust iRobot. The team seems to have anticipated which simple features and design additions, like bumpers and a foam barrier, would be the most useful, at the lowest cost. It also appears that they developed the product in a way that requires little human intervention.
The Braava is thoughtfully designed to be an effective iRobot sweeper/cleaner. Simplified assembly processes avoid high-cost processes. The design team seems to have considered the most important aspects of a robot cleaner and acted on it in an efficient and straightforward way, including bumpers to make sure it can navigate a living area without damaging furniture; weight to ensure proper cleaning and mopping; and practical, effective switches that get the job done.
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