Kitchen Robotics, a ‘Dark Kitchen’ innovator, uses Unitronics’ UniStream® PLCs, AC Servo Drives, & VFDs to create robotic ‘chef’ machines to receive customer orders from the cloud, then weigh, mix, and cook orders according to exact recipes, and even wash the pots.
Kitchen Robotics, a ‘Dark Kitchen’ innovator, wanted to create a new kind of robotic ‘chef’—a machine that could receive customer menu orders from the cloud and prepare the order automatically, independent of human intervention: selecting, weighing, and mixing the ingredients, exactly cooking the dish according to a strict recipe, place it into serving dishes—and that could even wash the pots.
The system had to be flexible, able to prepare a large number of dishes, yet allow for individual customer requests (hold the onion! extra cheese!), all while keeping the physical footprint small, so that the robotic chef machine, called the Beastro®, could fit through doorways.
The Beastro® system needed to perform a range of control functions, including complex motions, and also support connection to the cloud; unlike traditional restaurants with seating and storefront, ‘Dark Kitchen’ restaurants only supply take-away orders, and the vast majority of customer orders are placed online, via app.
The engineers on the project selected Unitronics UniStream® PLCs, AC Servo Drives, and VFDs, to do the job.
How the System Works
When a customer orders a dish via a website or app, the order details go up to the company's cloud. Recipes, toppings, and any special customer requests—all is processed in the cloud and sent directly to the UniStream PLC in real-time, using an API that implements a dedicated TCP/IP protocol written in UniLogic, Unitronics all-in-one development software.
UniStream checks the raw ingredients inventory, via sensors in the ingredient containers. If all ingredients are present in sufficient quantity, the robotic chef machine begins to prepare the order.
First, the recipe ingredients are assembled.
A key element of successful cooking—particularly for restaurants, where a dish must turn out the same every time—is the exact measuring of raw ingredients. This is accomplished via dosing stations comprising stepper motors controlled by serial communication; the system ensures accurate measurement by weight via closed-loop control. The system contains approximately 45 dosing stations that handle liquids, powders, and solids.
Unitronics VFDs control all mixing procedures, as well as the stirring of the pot contents, via serial communications.
During the cooking process, 6 Unitronics AC Servo axes transport the pots through the cooking stations, moving the pots on and off induction surfaces according to order.
When the dish is complete, the machine pours the pot contents into the serving dish and transports the pot is to the cleaning station to be washed and dried.
Specific Challenges
Communications. The Kitchen Robotics system required that the PLC connect to the cloud and execute commands in real time; this required the team to create an API and implement a dedicated TCP-IP protocol, using several ports simultaneously. In addition, the different system components used different protocols, both standard and dedicated—the UniStream PLC needs to communicate with over 60 components such as servos, VFDs, heaters, sensors, steppers, etc.
Servo Motion: the different axes of motion relied on different mechanisms: rack & pinion, roll feeders, linear and rotary actuators, and other dedicated mechanisms. The force of each axis had to be modified in real-time, while the systems was running. Each axis, edge sensor, mechanical brake, etc. required a different homing method.
In addition, there were issues of overlap—this was handled by using absolute encoders to check the current position before the start of any movement, and to change the speed of movement of each axis accordingly while mapping the current position throughout the movement. This enabled the system to achieve high levels of both efficiency and safety.
Steppers. By controlling the steppers via communication, the team was able to reduce costs by avoiding the complex wiring and integration that such a large number of steppers would otherwise require.
VFDs Electric motors produce a lot of EMI; in order to produce a machine with a small physical footprint so densely packed with motors, it is imperative to reduce the effects of EMI. Unitronics VFDs were chosen specifically because they offer built-in control via communication, instead of analog signals that are sensitive to electromagnetic noise.
Benefits of using Unitronics
This was the first project that Kitchen Robotics performed using Unitronics control products.
Their team selected Unitronics not only because the products filled all of the necessary requirements—they also recognized the advantages of Unitronics All-in-One Solution, which enabled them to easily obtain all control components for their complex Motion application from a single supplier: PLCs and HMIs, servo drives, motors, and VFDs – all seamlessly supported, commissioned, and programmed in UniLogic software.
The Unitronics approach to motion, Servo Made Simple, enabled them to define axes, implement control, analyze and track processes, while Unitronics motion experts were available to aid them throughout the project.
