Abstract

In environments where humans and robots collaborate closely, achieving a balance between safety, efficiency, and comfort presents a significant challenge. Excessive precautions, while ensuring the human operators’ safety, often compromise operational efficiency and comfort, particularly in tasks that blend coexistence and collaboration. To address these challenges, this study proposes a flexible control framework that dynamically adjusts the robot’s responsiveness to human movements, therefore, it can offer a balanced solution across safety, comfort and efficiency. The framework utilizes the dynamically-consistent generalized hierarchical control (DGHC) with the human-centric parameters, thereby establishing task priority rules under varied interaction scenarios. The parameters are defined to assess the risk of collision between a human and a robot, considering their relative positions and velocities. Experiments were conducted in blended scenarios with three levels of responsiveness. As the responsiveness increased, task efficiency and comfort decreased by 36% and 33%, respectively, while safety improved by 63%. The proposed framework allows a flexible solution that adjusts safety, comfort and performance, thereby offering a versatile solution adaptable to a various collaboration applications.

My contributions: 

Human Risk Assessment

• Developed a risk assessment model to quantify collision risk between coworker segments and robot parts.

• Considered relative distance and Speed Separation Monitoring (SSM) criteria from the ISO/TS 15066 standard.

Hierarchical control for whole-body force control and multi-task management 

• Implemented Whole-body control framework using Dynamically Consistent Generalized Hierarchical Control (DGHC). 

Task Priority and Transition Rule

• Task priority and transition rules implemented via a Finite State Machine (FSM)  considiering  risk  levles
  
  

• Managed 13 tasks corresponding to a total of 31 degrees of freedom (DOFs).