# Analysis and Design of a Minimalist Step Climbing Robot
## 7 Conclusions  
In this article, a new mechanism for a step climbing robot is discussed and consists of two front wheels, a rear wheel and an actuator (to control the center distance between the front and rear wheels). In order to compensate for the drastic variation in the inclination angle, which can result in instability, the angle between the connecting link and the body is varied. A dynamic model (of the proposed system) is developed and various simulations are performed. During the analysis of the model, it is found that the difference between allowable and required torque on the front wheels increases by 108.5% in the controlled condition than compared to the uncontrolled condition. This reduces the probability of slipping and improved the stability of the proposed system. It is observed that the robot carrying a load with a low center of gravity and for which its front and rear wheels are connected with a rigid frame is capable of climbing up or down the stairs. On the other hand, the robot fails to climb up and down when it is carrying a load possessing a higher center of gravity. During ascending simulations with control, the required torque on rear wheel is reduced by 26.3% than compared to uncontrolled simulations. Furthermore, the normal reaction of the rear wheel during descending simulation has increased by 170.9% by controlling the inclination angle, which reduced the probability of toppling of the proposed robot. Experiments on a scaled-down prototype also reveals that the robot is unable to climb up the stairs during uncontrolled conditions whereas in controlled conditions, it can successfully climb up the stairs. By controlling the inclination angle of the prototype, the variation of inclination angle during ascending is reduced by 77.8%, whereas the variation is reduced by 92.8% during descending. Similarly, during descending experiments, it was found that the robot topples when operated without control and the robot successfully climbs down the stairs when the inclination angle was controlled.  
As observed from the configuration of the system, the length of the proposed system will increase significantly due to the connecting link, which in turn will restrict such robots to operate in a confined space. In order to overcome such limitations, the connecting link should be replaced by a linear actuator. Moreover, a robust control method may be designed to enhance the performance of the robot during an external disturbance. Since cost is also a very important parameter, optimization should be performed without compromising the stability and strength of the robot. Furthermore, these models should be tested against external disturbances. Finally, full-size prototypes should be developed and experiments should be carried out to ensure the safe and stable operations of the robot.  
Conceptualization, N.J.B. and H.O.; methodology, N.J.B.; formal analysis, N.J.B. and B.B.; investigation, K.T.; resources, K.T.; writing--original draft preparation, N.J.B.;  
Figure 23: Robot schematic while descending; (**a**) with control; (**b**) without control.  
writing--review and editing, B.B.; visualization, K.T.; supervision, H.O.; project administration, H.O. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The authors declare no conflict of interest.