Posture control method for 4UPU−PU−RRU gantry-tracked temporary support robot

To ensure safety and efficiency during simultaneous excavation and bolting in coal mine roadways, temporary support must control the risk of roof collapse caused by unsupported roof exposure prior to permanent support completion. A gantry-type tracked temporary support robot with posture-adaptive capability has been developed to provide rapid and stable support under complex roof conditions, including vertical subsidence, longitudinal and lateral inclinations, and their composite deformations. A kinematic model of a 4UPU−PU−RRU parallel mechanism was established, in which inverse kinematics was solved geometrically and forward kinematics was computed efficiently using a Jacobian-based Newton–Raphson iterative method, enabling real-time mapping between the target support posture and the extensions of four electric cylinders. A PLC-based servo control system with a dual-loop PID framework was designed, using tilt sensor feedback and inverse kinematics to compute real-time compensation values for precise posture adjustment. Tests on a 1∶5 scale prototype showed that under step response, the posture angle error (X-axis ≤ 0.036°, Y-axis ≤ 0.024°) and response time (≤1.1 s) satisfied strict requirements. Under simulated dynamic composite deformation, the maximum error was 0.89°, with mean absolute and root mean square errors below 0.26° and 0.33°, respectively, demonstrating effective adaptation to variable roof deformations and ensuring tight support-roof contact. An intelligent temporary support solution is provided, contributing to safer and more intelligent tunneling operations.