圧力制御の併用による空気圧シリンダの適応的力制御

Abstract

The performance of a pneumatic force control system is affected by the characteristics of objects, compressibility of air, friction between cylinder and piston, etc. To suppress the influence of these factors, a combined control method using a P-D pressure controller for the cylinder and an adaptive model reference controller for the total system is presented in this paper. The P-D gains are determined experimentally, and the pressure command signal is produced by the adaptive controller, which is constructed based on the discretization of the third-order continuous-time transfer function with a lag time.Force control experiments were carried out for hard and soft objects using two kinds of controllers, that is, (A) adaptive controller without pressure control and (B) adaptive controller with pressure control. Comparing the experimental results by (A) and (B), the tracking error between the reference force signal and applied force was greatly improved by the proposed controller (B), and especially, steady-state error of (B) was 0.5N for hard object and 0.7N for soft object in the sense of the root mean square of 30 trials. The robustness of (B) to the sudden change in the supplied pressure was also confirmed.