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Page 73                             Li et al. Intell Robot 2021;1(1):58-83  I http://dx.doi.org/10.20517/ir.2021.08



































               Figure 12. The comparisons of the traditional backstepping control and bio-inspired backstepping control. A: tracking a straight line; B:
               linear velocity estimates of tracking a straight line; C: peak linear velocity comparison of tracking straight line; D: tracking a circular line; E:
               linear velocity estimates of tracking a circular line; F: peak linear velocity comparison of tracking a circular line  [95] .

               In addition, the shunting model also incorporated with PID controller to modify the error term, this control
               strategy provided a smooth velocity curve and more importantly, avoided impulse acceleration and torque,
               which could potentially damage the mechanical system [92] .


               In order to improve the efficiency and effectiveness of the bio-inspired backstepping control, the parameters
               of the control were determined using a genetic algorithm [93] . Tuning control parameters with the genetic algo-
               rithm provided better results than the implementation of bio-inspired backstepping control alone. Although
               the parameters tuned with the genetic algorithm provided satisfactory results, many other optimization meth-
               ods could be used to choose the parameters, a comparison study could be tested to demonstrate the efficiency
               of the genetic algorithm. A biologically inspired full-state tracking control technique was proposed to gen-
               erate smooth velocity commands [94] . The proposed control considered both position error and orientation
               error as the control input and used the shunting model to constrain its output to reach its goal of providing
               a smooth velocity curve. There are still some improvements can be made as the path itself is not smooth but
               has sharp turns before it tracks its desired trajectory in a straight line tracking simulation. In addition to the
               simulation studies, successful implementation on a real mobile robot system demonstrates the effectiveness of
               the bio-inspired backstepping controller [14] . The experiment results showed that the robot tracked both the
               straight path and the circular path, and simulation results provided smooth velocity curves.



               The mobile robot usually works in a complicated environment, which system and measurement noises can
               affect its tracking accurate. Therefore, an enhanced a bio-inspired backstepping control was proposed to gen-
               erate the smooth, accurate velocity and torque command for mobile robots, respectively [95] . The total control
               Incorporated bio-inspired backstepping controller with unscented Kalman and Kalman filters that were suit-
               able in real-world applications. The proposed control considered noises in real-world applications, and the
               proposed control considered such noises effect and successfully eliminated it. However, the proposed control
               is considered a fixed noise, which is not true in real-world applications.
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