Development of a Conveyor Belt Digital Twin

Using Unity and C# scripts for physics, I explore here how to replicate the movement of conveyor belts

About the Thumbnail: This is the made demonstration of series of conveyor belts, inclined and positioned to have a infinite loop sequence!

OVERVIEW:

This project explores the creation of a digital twin for a conveyor belt system using Unity3D and C# scripting to simulate real-world physics behavior.
A digital twin is a virtual representation of a physical system that mirrors its dynamics in real time, enabling engineers to test, optimize, and visualize performance before physical prototyping.

The goal of this project was to:

  • Recreate a physics-based conveyor belt prototype in Unity.
  • Understand how colliders, rigidbodies, and C# physics scripting interact to produce controlled motion.
  • Experiment with scripted vs. natural physics behavior, and study the impact of FixedDeltaTime, DeltaTime, and frame rate (FPS) on simulation accuracy.
  • Apply quaternion rotation logic for conveyor belt orientation and movement consistency across update loops.

Note: Files are available upon reasonable request!

METHODOLOGY:

Explanation video for the virtual commisioning

Project Setup:

The conveyor belt system was modeled using Fusion360 exported as .fbx files and additional components using Unity’s GameObjects hierarchy:

  • Base Frame – static structure with box colliders.
  • Belt Surface – moving collider surface simulating belt transport.
  • Rollers / Guides – rotating parts driven by torque or scripted rotation.
  • Objects – cubes or packages interacting with the belt using rigidbody components.

IMPORTANT: You have to have a fundamental understanding of conveyor belt systems to make design and known the interactions needed for the materials to move.

Each physical component was assigned:

  • A Collider (BoxCollider or MeshCollider) to define its physical boundary.
  • A Rigidbody to enable force-based interactions or scripted motion updates.

Physics Consideration

BoxColliders were used for both the belt and packages.

  • The belt collider remained kinematic, while the object rigidbody responded dynamically.

  • physics Material was applied to tune friction and bounciness to achieve smooth transport.

  • FixedUpdate() → runs at a constant time step Time.fixedDeltaTime ≈ 0.02s by default. Ideal for physics calculations to ensure deterministic outcomes.

This basically runs every frame and depends on FPS Time.deltaTime.

Euler angles often introduce gimbal lock and interpolation errors when rotating moving belts or rollers. To achieve stable rotation along the conveyor path, Quaternion math was utilized. Quaternions are essential when simulating rotational systems like roller shafts, servo-driven belts, or robotic joints, ensuring stability even during chained axis rotations.

LEARNINGS:

I was able to understand the relationship between colliders, rigidbodies, and scripting for stable digital twinning. Overreliance on Unity’s default physics may cause unpredictable jitter; balancing natural and scripted physics offers better control.

Another thing would be the use of FixedDeltaTime to govern reliable motion updates, while DeltaTime varies with rendering speed.
Keeping motion updates in the physics loop ensures fidelity between simulation and real-world conveyor behavior.

Digital Twin Realism towards Virtual Commisioning

Achieving accurate digital twin behavior requires not just visual realism but also temporal and dynamic consistency.
Unity’s physics engine, when combined with deterministic scripting, can mirror real mechanical timing closely. This is often done as virtual commisioning to validate control mechanical systems before deployment reducing cost and the need to setup and prototype the product in the field.

HOW THIS PROJECT CAN BE FURTHER IMPROVED: This falls under mechanical systems, computer-aided engineering as we are validating the mechanical systems utilized by utilizing Unity's physics simulation. What I did not focus on was the other aspect of the digital twin which is when we apply this for monitoring and asset management. This will involve getting access to sensors and replicating that information to a 3D model which is hard to replicate in Unity. This is merely done for virtual commissioning or the act of using simulation tech for control systems before it is applied in the field.

Better use case of digital twinning for monitoring will need the use of vendor specific software like that of Siemens and Schneider Electric or get a copy of Vision Components software where you can monitor the movement based on control feedback signals connecting it via OPC-UA!