In context
By early 2025, robotic grinding of complex curved parts remained challenging due to force fluctuations from workpiece curvature uncertainty, which degrade surface quality. Traditional position-based impedance control struggled when workpiece geometry and stiffness were unknown or mismatched, limiting automation of precision finishing tasks.
What was reported
Researchers from Shenyang Jianzhu University and the Shenyang Institute of Automation (CAS) proposed a force control method that integrates a variable integral PID feedforward controller with an adaptive impedance control algorithm. The system uses a 6-axis force sensor and real-time robot end-effector position to update motion bias online, enabling accurate force tracking without prior knowledge of workpiece parameters.
The adaptive law, based on Lyapunov stability, estimates environment stiffness, damping, and position to adjust the reference trajectory. The variable integral PID reduces overshoot and integral saturation, improving dynamic response and disturbance rejection.
Simulations and experiments showed faster response to parameter changes, reduced force tracking error, and shorter settling time compared to constant-parameter impedance control. In grinding tests on variable-curvature surfaces, surface roughness improved from about 0.6 μm to nearly 0.4 μm.
Why it mattered
This work addressed a key limitation in robotic grinding—handling unknown, varying workpiece conditions—by combining adaptive control with practical PID enhancements. The demonstrated improvement in surface quality supports wider adoption of robots for precision finishing of complex parts, where consistent force control is critical.
“The proposed method can quickly respond to the change of workpiece parameters, effectively reduce the tracking error of contact force, and shorten the steady-state adjustment time.”
Source: 《机器人》期刊 (robot.sia.cn) · Published 2025-03-15 · “机器人磨削力控变速积分自适应阻抗控制”