Constrained robot control using control barrier functions

Many robotic applications, especially if humans are involved, require the robot to adhere to certain joint, workspace, velocity or force limits while simultaneously executing a task. In this paper, we introduce a control structure, which merges an arbitrary desired robot behavior with given constraints. Using a quadratic program (QP), control barrier functions (CBFs) are combined with an arbitrary nominal control law, which determines the desired behavior. The CBFs enforce the constraints, overruling nominal control whenever necessary. We show that the concept is applicable with arbitrary numbers of constraints and any nominal control law. In order to illustrate the capabilities of the approach, the control scheme is applied to an anthropomorphic manipulator, which is constrained by static as well as moving constraints.

Authors

• Manuel Rauscher
• Melanie Kimmel
• Sandra Hirche

Keywords

• Aerospace electronics
• Control design
• Service robots
• Rendering (computer graphics)
• Predictive control
• Constrained Control
• Control Barrier Functions
• Control Strategy
• Optimal Control
• Workspace
• Control Structure
• Quadratic Programming
• Nominal Control
• Capability Of This Approach
• Control Values
• Nonlinear Systems
• Inequality Constraints
• Relative Degree
• Robotic System
• Lipschitz Continuous
• Model Predictive Control
• End-effector
• State Constraints
• Constraint Violation
• Multiple Constraints
• Input Constraints
• Impedance Control
• Lie Derivative
• Locally Lipschitz
• Presence Of Constraints
• Constraint Qualification
• Nominal Input
• Cartesian Position
• Admissible Values
• Development Of Control Strategies