Precise Automation of Rotary Flexible Link Manipulator Using Hybrid Input Shaping With Single State Feedback Fuzzy Logic and Sliding Mode Controllers

Abstract

Flexible link manipulators (FLM) are widely preferred in applications that require faster operation, high maneuverability, and less energy consumption. However, their flexibility is associated with undesired vibrations, making accurate positioning challenging. As most of the existing controllers are model-based, their performances are affected by uncertainties and often require the feedback of all the states. This makes such control challenging and expensive. Interestingly, despite its poor position tracking, the input shaping control (ISC) proved to be effective in oscillation suppression of flexible structures. In this paper, precise automation of the FLM is presented by hybridizing an improved input shaping control (iISC) with a model-free fuzzy logic control (FLC), and the model-based sliding mode control (SMC). The single feedback FLC, and SMC were designed for the position control while the iISC provided the tip deflection control. Three parameters of the FLM, namely, the length, mass, and spring stiffness of the link were used to assess the sensitivity of the controllers. With the maximum velocity of 94 deg/s and the maximum r.m.s of 0.33 deg, ISC+FLC has increased the velocity of the iISC by at least 77% and improved the poor oscillation suppression of the FLC by at least 64%. Thus, the analysis demonstrated that the iISC+FLC could provide precise automation of the FLM by measuring the output of only one state (position), making it cost-effective and reduces the complexity and computation time of the full-state feedback controllers.

Keywords

• Dynamic modelling
• flexible link manipulator
• position tracking
• sensitivity analysis
• tip deflection
• vibration suppression