Flexible Link Lumped Masses Manipulators

Flexible link robots offer distinct advantages over rigid robots in various applications. Lightweight flexible link robots often require less energy to operate; they are more easily transportable which is valuable in aerial, space, and mobile robotics; and they exhibit compliance, which is an interesting feature in assembly operations or collaborative work alongside humans. Nevertheless, the flexibility of the links can lead to unwanted vibrations and oscillations during motion, which can affect the precision and the overall performance of the concerned system. Hence, achieving a precise mission with these robots requires accurate dynamic modeling and control strategies in order to manage vibrations and ensure accurate positioning. Key challenges in the design of controllers for flexible manipulators include nonlinearity, sensor and actuator disturbances, and sensitivity to payload changes. Accurate dynamic modeling is crucial, where flexible links exhibit distributed elastic and kinetic energy effects, typically modeled using the Euler–Bernoulli equation. However, this results in infinite-dimensional models, often truncated using methods like assumed modes, finite elements, or lumped masses. The successful control of flexible robots necessitates navigating these challenges and selecting appropriate modeling and truncation methods for dynamic equations. Lumped masses models provide a good compromise between an accurate dynamic model and its ease of use in the analysis and design of the robot control system. This chapter studies this modeling approach and develops some examples of how these models can be used to develop efficient linear and nonlinear control systems for flexible link robots. Experimental results are reported in order to justify the efficiency of the control systems yielded by this modeling approach.