Energy-Aware Adaptive Force-Admittance Control for Robotic Manipulators: Application in High-Precision Aircraft Assembly

An energy-aware adaptive force-admittance control strategy is proposed, which integrates accurate force regulation through a direct force controller with compliant motion enabled by adaptive admittance control. This combined mechanism addresses environmental uncertainties while simultaneously regulating wrench and position. However, the admittance adaptation and direct force controller introduce nonpassive behaviors, undermining the system’s passivity. To resolve this issue, a virtual energy tank is introduced to monitor the energy associated with nonpassive actions, ensuring energy boundedness and restoring system passivity for stable interaction with passive environments. To further enhance safety and performance, the proposed scheme incorporates online energy injection and freezing mechanisms. When the tank’s energy level falls below a preset threshold, additional energy is injected to improve control performance. Conversely, when the exerted wrench exceeds specified limits, the control system reverts to a constant admittance model to maintain compliance, effectively freezing any additional energy extraction. Two activation functions are also developed to ensure precise positioning in the direction of position control. The effectiveness of the proposed approach is validated through real industrial robot applications in aircraft assembly tasks. Experimental results demonstrate its superiority in improving both task performance and operational safety.