Overview

In this project, we built a payload control environment, trained a reinforcement learning–based control model, developed a camera-based yaw estimation model, and finally integrated both models for demonstration on a Raspberry Pi. The final system successfully controlled the payload yaw under external disturbances.

Payload Control Environment

A simulation environment was developed that includes the control unit, suspended payloads (truss, H-beam, and plate), ropes, and a crane. The environment supports multiple payload configurations and external disturbance conditions for both development and performance evaluation.

Payload control unit with four thrusters
Truss payload used for control experiments

Control Model Training

A reinforcement learning–based control model was trained to rotate the suspended payload to the target yaw angle. Representative control results are shown below under X-direction (X1Y0) and X/Y-direction (X1Y1) disturbance conditions. The model successfully achieved the target yaw under both disturbance conditions.

Yaw control results under X1Y0 disturbance conditionsYaw control results under X1Y1 disturbance conditions

Yaw Estimation

A camera mounted on the control unit captures images used to estimate the payload yaw angle. Colored hooks are first detected, and image-processing methods tailored to each payload geometry are then applied to determine the yaw angle. The examples below show the estimation process for the H-beam, plate, and truss payloads.

Yaw estimation examples for H-beam, plate, and truss payloads

Vision-Based Control

The payload yaw estimation model and the reinforcement learning–based control model were integrated and executed on a Raspberry Pi. The results below compare the Raspberry Pi implementation with the development environment under identical disturbance conditions, demonstrating equivalent control performance.

Control results in the development environmentControl results on Raspberry Pi