There is a high demand for developing effective controllers to perform fast and accurate operations for either flexible link manipulators (FLMs) or rigid link manipulators (RLMs). Thus, this paper is beneficial for such vast field, and it is also advantageous and indispensable for researchers who are interested in robotics to have sufficient knowledge about various controllers of FLMs and RLMs as the controllers’ concepts are elaborated in detail. The paper concentrates in critically reviewing classical controllers, intelligent controllers, robust controllers, and hybrid controllers for both FLMs and RLMs. The advantages and disadvantages of the aforementioned control methods are summarized in this paper; it also has a detailed comparison for the controllers in terms of the design difficulty, performance, and the suitability for controlling FLMs or RLMs.

Fig buttercup is a perennial herb native to Europe, temperate Asia, and northern Africa. In eastern North America, fig buttercup competes with native spring ephemerals, complicating control techniques. If chemical control could be shifted earlier in the year, the potential to negatively impact spring ephemerals would be reduced. We tested glyphosate applications on fig buttercup in northern Virginia under three early phenological phases (preflowering, early flowering, and 50% flowering) to assess the effectiveness of early-season treatment. Treating when approximately half of the plants in the population were in flower resulted in a 95% decline in fig buttercup. Treating when the first flower in the population had emerged resulted in a 90% decline. No later phenological phases were treated. Control of fig buttercup led to an increase in cover of Japanese stiltgrass, an invasive grass.