omicro Flux

1. Introduction

omicro Flux is a balance control spherical robot developed as a successor to the conventional omicro. The name "Flux" represents magnetic flux as well as the continuous movement of sensor data and state changes. Its key feature is the significant precision improvement achieved by switching from conventional DC motors to M5Stack BLDC Roller485.

With its configuration of BLDC motors, IMU, and custom control boards, the robot maintains balance while moving within a sphere, enabling the realization of advanced interaction experiences such as the XR project Boundary Blur.

2. Development Background

The development of omicro Flux has a clear background. Previously, we operated a spherical robot called "omicro" in an XR project called "Boundary Blur".

What is Boundary Blur

Boundary Blur is a multi-agent system based on the concept of blurring the boundaries between the physical world and digital world. It is a project that aims to have spherical robots omicro existing in real space collaborate with AI agents in virtual space to perform tasks, utilizing Mixed Reality technology.

The system configuration involves scanning and meshing real space using iPad Pro's LiDAR sensor and ARFoundation to build a digital twin world on top of it. OpenCV image recognition tracks the position of the real omicro and places the robot's digital twin in AR space. This digital twin interacts with virtual space objects and AI agents according to physical laws, with results fed back to the real omicro. In other words, when the real robot "collides" with virtual space objects, it actually stops, and when virtual AI agents "track" the robot, the real robot takes evasive action - creating a system where the physical and virtual worlds mutually influence each other.

Emergence of Technical Challenges

However, as we accumulated exhibition experiences with Boundary Blur, the technical limitations of omicro became apparent. The onventional omicro used DC motors for control, but DC motors, by their nature, have difficulty controlling rotation at low speeds, and due to the spherical robot structure with minimal ground contact, stopping control was also extremely difficult. When operating omicro alone, this wasn't a major issue since precise control wasn't required, but when trying to accurately control the robot according to xR operations and interactions in the Boundary Blur system, these control precision limitations became prominently apparent.

Furthermore, the conventional omicro used geomagnetic sensors to obtain orientation, but geomagnetic fields are easily affected by surrounding metal objects and electronic devices, making stable orientation detection difficult in exhibition environments. To enhance the precision of XR app interactions, we determined that implementing more advanced interaction experiences in Boundary Blur would be impossible without solving these fundamental problems. This led to the development of omicro Flux as the successor to omicro.

Foundation for Swarm Control Systems

Another important motivation for developing omicro Flux was building the technical foundation for future swarm control systems. Improving individual robot control precision is a prerequisite for multiple robots to perform coordinated operations. Without individual robots achieving accurate position control and stable communication, functioning as a swarm is impossible.

In particular, for multiple spherical robots to function as "new wheels, " precision that could never be achieved with conventional DC motor control was necessary. Establishing a control system where each robot can perform coordinated operations with minimal error and dynamically change roles was essential. The high-precision control technology realized in omicro Flux represents the first step toward this vision.

3. System Configuration

omicro Flux operation requires the following procedures through hardware and software coordination:

3.0 System Setup Procedures

1. Initial Setup
Place omicro Flux on a flat, stable floor surface. Due to the sphere's characteristics, avoid use on inclined or unstable surfaces.

2. Communication Establishment
After powering on omicro Flux, launch the dedicated iOS application and establish wireless communication via Bluetooth Low Energy (BLE). Connection status can be confirmed on the application screen.

3. Sensor Calibration
For precise orientation control, execute 9-axis IMU sensor calibration from the iOS application. This process compensates for magnetic influences in the installation environment, enabling high-precision attitude estimation.

4. Control Start
After calibration completion, start omicro Flux movement control from the iOS application or watchOS application on Apple Watch.

3.1 Spherical Robot

omicro Flux consists of an outer sphere and an internal robot, similar to conventional omicro, but with significant improvements to the internal system.

Outer Sphere

The outer sphere uses clear plastic made from styrene resin. The surface is coated with tempered glass coating agent, enhancing durability and visibility. This structure remains the same as conventional omicro.

Internal Robot

omicro Flux's greatest feature is the significant change in control system. Switching from conventional DC motors to M5Stack's BLDC Roller485 enables precise control.

Roller485 is an integrated brushless DC motor motion control kit that combines not only BLDC motors but also angle sensors and displays.

The change from DC motors to Roller485 achieved the following significant improvements:

• High torque control with BLDC: Adopting brushless DC motors enabled precise control in low-speed ranges that was difficult with conventional DC motors
• Reduced failure factors: BLDC's brush-free characteristics significantly reduced failure risks from mechanical wear
• Accurate movement control: Built-in angle sensors enable precise measurement and control of rotation amounts, making PID control implementation possible

Furthermore, by newly adding M5Stack Unit Pro, high-precision attitude estimation using 9-axis IMU (3-axis gyroscope, 3-axis accelerometer, 3-axis magnetometer) was realized. This 9-axis IMU enables stable orientation detection and attitude control that was difficult with conventional single geomagnetic sensors.

Also, changing from conventional matrix LEDs to Unit Puzzle enables expressive eye representations using colors, improving the robot's friendliness.

This integrated design combines multiple components required in conventional systems, achieving simplified wiring and improved control precision. Using custom control boards combined with these high-precision sensor groups realizes balance control within the sphere.

Wheels and Movement Mechanism

omicro Flux has a total of 10 wheels, with power connected only to the two large wheels at the bottom. Since large wheels in conventional omicro caused severe wear due to torque increase, omicro Flux changed to "Black Resin" with smooth surface and low shrinkage, high toughness characteristics. Since direct contact between rubber tires and sphere creates excessive grip, medical surgical tape is used to adjust friction.

The other 8 wheels don't contact the sphere's inner wall when stationary but touch the inner wall during operation. This provides "ball straight-line stability improvement," "impact absorption," and "axis retention during rotation." When wheels rotate, the internal robot climbs the sphere's inner wall, propelling the ball forward. Ball direction changes through wheels rotating in opposite directions at equal speed, performing super pivot turns and enabling rotation in place.

Frame Design Renewal

During the rebuilding process from omicro to omicro Flux, the addition of new components like Roller485 and Unit Pro changed the center of gravity balance entirely, requiring complete frame redesign. For areas requiring light transmission like Ring LED covers, "8001 Resin" with transparency, toughness, and excellent dimensional stability is used, achieving both visibility and durability.

Posture Control

omicro Flux features a posture control function. Its strength lies in the spherical design, which does not topple over even when posture control is turned off. By applying posture control only partially, it can still preserve movements that make use of inertia. Learning posture control is normally very difficult, requiring repeated falls or throws, but with this structure, many more trial-and-error attempts are possible. The combination of the fun of rolling with inertia and the freedom to control only the parts that truly need it is what makes this robot truly unique.

3.2 Operation Applications

omicro Flux operation uses dedicated iOS and watchOS applications. For detailed functions and operation methods of these applications, refer to "omicro Series Dedicated Applications".

Main improvements in omicro Flux compatible version:

• BLDC Motor Support: New control interface supporting precision control
• High-Precision Control: Improved rotation and movement control systems
• Haptic Feedback Joystick Control: Enables operation with haptic feedback during joystick control. Acceleration/deceleration control through push amount. Since simple acceleration/deceleration/stop operations make movement control difficult, algorithms converting to internally optimal values are implemented

4. Future Vision: "New Wheels" Through Swarm Control

omicro Flux development doesn't stop at single robot performance improvement. It aims to swarm control multiple spherical robots, making them function as cooperating "new wheels".

4.1 Beyond Conventional Wheels

Conventional wheels are fixed disc-shaped objects capable only of simple rotational movement around a rotation axis. However, swarm control systems using omicro Flux as components enable building dynamic movement systems where individual robots possess intelligence and cooperate/adapt according to situations. This is a challenge to fundamentally redefine the concept of wheels itself.

omicro Flux itself doesn't incorporate swarm control systems. omicro Flux is designed as a spherical robot achieving high-precision single unit control, with swarm control functions complemented by higher-level systems like Boundary Blur. This design allows omicro Flux to function both as wheels and as part of multi-agent systems.

4.2 Function Enhancement Through Swarm Control

Higher-level systems like Boundary Blur controlling multiple omicro Flux enable the following functions:

Cooperative Movement: Multiple robots collaborate to realize movement patterns difficult for single units

Distributed Control: System-wide loads are distributed among multiple robots for efficient operation

Redundancy Assurance: When some robots encounter problems, other robots complement functions

Environmental Adaptation: Integrating sensor information from each robot performs optimal control according to environment

4.3 Technical Foundation

Realizing this concept requires high-precision control technology cultivated in omicro Flux:

• Precise Position Control: BLDC control and PID control by Roller485 enable accurate positioning necessary for swarm control
• Real-time Attitude Estimation: High-precision sensor information from 9-axis IMU enables accurate grasp of individual robot states
• Stable Communication: BLE communication optimization enables cooperative control among multiple robots
• Environmental Recognition: Integrating sensor information from each robot builds comprehensive understanding of surrounding environment

4.4 Application Possibilities

Movement systems integrating multiple omicro Flux as wheels provide adaptability to mobile units that conventional fixed wheels cannot achieve:

Automated Transport Systems: Vehicles optimizing wheel positions according to cargo shape and weight distribution Mobile Robots: Robot systems realizing flexible movement strategies in diverse work environments

4.5 Path to Paradigm Shift

omicro Flux represents the first important step toward this vision. By establishing high-precision single unit control, it builds the technical foundation for the next phase of swarm control by higher-level systems. Knowledge gained through demonstration experiments in the Boundary Blur project will be directly utilized in developing future multiple robot cooperative control systems.

This effort aims for innovation in movement technology in the robotics field, pursuing realization of intelligent, adaptive movement systems beyond conventional mechanical constraints. omicro Flux is the first step providing foundational technology of high-precision control as a component for realizing that vision.