Scaling the Infinite Kitchen: Robust Motion Control for Food Robotics

Producing 500 salad bowls per hour represents a massive leap in efficiency over traditional manual food preparation, typically topping out around 350 bowls per hour. Achieving this throughput required a fundamental reimagining of the fast-casual restaurant "makeline", the linear assembly station where staff manually apply ingredients.

To solve this, the engineering team at Sweetgreen developed the "Infinite Kitchen." This proprietary robotic system automates the assembly of salads and bowls, utilizing a friction-less conveyor and automated dispensing tubes to deliver precise portions. While the machine relies on complex logic to manage orders, the motion control backbone required a solution that balanced industrial reliability with integration simplicity.

For Brady Knight, Director of Automation, the challenge was finding motion control components that could facilitate rapid iteration without needing to be replaced for the final commercial rollout. The team selected Teknic ClearPath-MC integrated servos early in the design phase and kept them through to production.

This dual-purpose capability allowed the engineering team to move from concept to functional machine faster, avoiding the friction often associated with upgrading low-end prototyping motors to industrial-grade servos.

One of the most critical stations in the Infinite Kitchen is the salad mixer. This mechanism spins the bowl to ensure dressing and ingredients are evenly mixed, a task that is often inconsistent when done by hand.

The application utilizes a ClearPath-MC (Motion Controller) unit to execute a multi-step sequence. According to Brady, the motor drives a bar linkage arm that swings out to grab the bowl. Once secured, the system executes a rapid spin profile—rotating 720 degrees to mix the contents—before retracting and placing the bowl back onto the conveyor.

By using the ClearPath-MC series, the team could rely on the motor’s internal intelligence to handle positioning logic. The system uses simple inputs to trigger pre-programmed moves—such as "In," "Out," and "Spin"—eliminating the need for complex external motion controllers or heavy coding for simple point-to-point tasks.

While the Infinite Kitchen is a sophisticated automated system, the motion requirements for tossing salad are pragmatic. The application doesn't demand the micron-level precision of semiconductor manufacturing, but it requires extreme reliability in a washdown environment.

Although ClearPath is frequently deployed in high-precision applications, Sweetgreen’s engineering team selected it for a different set of reasons: industrial durability combined with ease of use. Brady describes the motor as being in the “sweet spot.” While he notes that the specific motion profiles “don't have to be super precise” given the nature of handling food, the ClearPath servo provides high-performance, closed-loop control in a ruggedized package (rated IP67 with M12 connectors). This ensures the machine withstands the rigors of a commercial kitchen without the complexity often associated with industrial servos.

Furthermore, the software interface proved intuitive enough for the entire team, not just the controls specialists. “The fact that the user interface is friendly enough for someone who more casually works on the machine makes it really appealing to use cross functionally across the team,” says Brady.

Beyond the hardware, the long-term partnership with Teknic has been a deciding factor for Sweetgreen. Having a dedicated application engineer who understands the machine's history has streamlined troubleshooting and development.