Summary

A bartender robot, barobo, was developed. After setting a cup on the tray and placing an order on the touch panel, barobo carries the cup and automatically pours the drinks. Of course, the drink combinations are unlimited!

Purpose

• Develop a robot for a university festival as a robot club

• Experience short-term development as a "hackathon.”

Process

Discussion of Idea

The decision was made on what to develop. Based on last year's exhibit experience, the criteria were "a robot that is easy to prepare and clean up and has high customer turnover efficiency. Ultimately, we decided on a robot that automatically pours multiple types of drinks and makes cocktails. The name "barobo" came from "bartender robot.

Preparation

It was decided to allow one week in August for members to concentrate on the project's development. Since it was necessary to start work on the first day, the tank and tap were selected in advance. The tank had to be lightweight and made of a material that would not break, and the tap had to be able to open and close with the torque of a servo motor for radio control. Therefore, a plastic water jug sold at a 100 yen store was selected.

Organize Development Flow

At first, the development flow and new points needed to be tested were described and organized on a whiteboard. A rough image was shared at this point, and each member began work.

Experiment

The issue was how to pour the specified amount of water into the cup when the program controls the opening and closing of the tap. With the time-based control, the amount of drink poured depends on the remaining liquid. To solve this problem, distance sensors were installed on the top of each tank to calculate the remaining amount of drink and the time to open the tap based on the height of the liquid surface, and the appropriate amount was poured.

The amount of water in the tank was varied in three steps (50 ml, 100 ml, and 150 ml), and the time required for a certain amount to flow out into a cup was measured. The results were summarized in a graph to obtain an approximate curve for the time it takes to open the faucet to pour a certain amount of water at a given water level. This approximate equation was written into the program that controls the robot, and a mechanism was constructed to ensure that a constant amount of water is poured even if the water level changes.

Hardware Design

The tanks are arranged in the upper section, and a tray carrying cups moves through the middle area. The tray is driven by a stepping motor and timing belt, and a switch is installed for zero-point adjustment. The primary material is an aluminum frame.

Electronic Circuits and Wiring

Considering a large number of sensors and actuators, three microcontrollers were used; the processing of the microcontrollers is divided into (1) stepping motor control, (2) ultrasonic distance sensor data acquisition and servo motor control, and (3) overall management. Data can be sent and received between (1) and (3) and between (2) and (3) via serial communication.

Software

The interface was created in Processing. The menu screen displays on a tablet PC, and the customer selects a drink. The customer can choose either a soft drink or a cocktail. When the customer presses the decision button, the data is sent to the microcontroller that controls the system via serial communication. The robot repeatedly moves the cup and controls the appropriate tap according to the menu, and finally returns the cup to the starting point.

Results

Exhibition

Throughout the three-day university festival, many people saw our system. We were able to operate without any significant problems during the festival.

Award

We submitted this work to the Monozukuri Culture Exhibition 2018, sponsored by Original Mind Inc., and received the fabcross award.

Experiences

• Experience in short-term intensive development (hackathon).

• Experience running a self-made mechatronic system continuously for three days.

• Experience in submitting work to contests.