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ICP-Based Pallet Tracking for Unloading on Inclined Surfaces by Autonomous Forklifts

Takuro Kato, Mitsuharu Morisawa

TL;DR

A control method for autonomous forklifts to unload pallets on inclined surfaces, enabling the fork to be withdrawn without dragging the pallets, and the effectiveness of the proposed method is verified through dynamic simulations and experiments using a real forklift that replicate unloading operations onto the inclined bed of a truck.

Abstract

This paper proposes a control method for autonomous forklifts to unload pallets on inclined surfaces, enabling the fork to be withdrawn without dragging the pallets. The proposed method applies the Iterative Closest Point (ICP) algorithm to point clouds measured from the upper region of the pallet and thereby tracks the relative position and attitude angle difference between the pallet and the fork during the unloading operation in real-time. According to the tracking result, the fork is aligned parallel to the target surface. After the fork is aligned, it is possible to complete the unloading process by withdrawing the fork along the tilt, preventing any dragging of the pallet. The effectiveness of the proposed method is verified through dynamic simulations and experiments using a real forklift that replicate unloading operations onto the inclined bed of a truck.

ICP-Based Pallet Tracking for Unloading on Inclined Surfaces by Autonomous Forklifts

TL;DR

A control method for autonomous forklifts to unload pallets on inclined surfaces, enabling the fork to be withdrawn without dragging the pallets, and the effectiveness of the proposed method is verified through dynamic simulations and experiments using a real forklift that replicate unloading operations onto the inclined bed of a truck.

Abstract

This paper proposes a control method for autonomous forklifts to unload pallets on inclined surfaces, enabling the fork to be withdrawn without dragging the pallets. The proposed method applies the Iterative Closest Point (ICP) algorithm to point clouds measured from the upper region of the pallet and thereby tracks the relative position and attitude angle difference between the pallet and the fork during the unloading operation in real-time. According to the tracking result, the fork is aligned parallel to the target surface. After the fork is aligned, it is possible to complete the unloading process by withdrawing the fork along the tilt, preventing any dragging of the pallet. The effectiveness of the proposed method is verified through dynamic simulations and experiments using a real forklift that replicate unloading operations onto the inclined bed of a truck.
Paper Structure (11 sections, 8 equations, 10 figures, 2 tables)

This paper contains 11 sections, 8 equations, 10 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Related Work
  3. Pallet Unloading Control
  4. Coordinate system
  5. Pallet tracking using ICP
  6. Fork withdraw control
  7. Experiments
  8. Experimental platform
  9. Simulation
  10. Experiments with a real forklift
  11. Conclusion

Figures (10)

  • Figure 1: Autonomous unloading on inclined surface with our ICP based pallet tracking method. Right image indicates point cloud measured by RGBD camera.
  • Figure 2: Initial and final states of unloading task
  • Figure 3: Flowchart of pallet tracking control
  • Figure 4: Limit switches for loading detection attached with fork
  • Figure 5: Overview of proposed system architecture
  • ...and 5 more figures