Editing Robot locomotion (section)

== Multi-modal robot locomotion based on bio-inspiration ==
'''Modeling of a multi-modal walking and gliding robot after Pteromyini (flying squirrels)'''

Following the discovery of the requisite model to mimic, researchers sought to design a legged robot that was capable of achieving effective motion in aerial and terrestrial environments by the use of a flexible membrane. Thus, to achieve this goal, the following design considerations had to be taken into account:

1.       The shape and area of the membrane had to be consciously selected so that the intended aerodynamic capabilities of this membrane could be achieved. Additionally, the design of the membrane would affect the design of the legs since the membrane is attached to the legs.<ref name=":0" />

2.       The membrane had to be flexible enough to allow for unrestricted movement of the legs during gliding and walking. However, the amount of flexibility had to be controlled due to the fact that excessive flexibility could lead to a significant loss of energy caused by the oscillations at regions of the membrane where strong pressure occur.<ref name=":0" />

3.       The leg of the robot had to be designed to allow for appropriate torques for walking as well as gliding.<ref name=":0" />

In order to incorporate these factors, close attention had to be paid to the characteristics of the flying squirrel. The aerodynamic features of the robot were modeled using dynamic modeling and simulation. By imitating the thick muscle bundles of the membrane of the flying squirrel, the designers were able to minimize the fluctuations and oscillations on the membrane edges of the robot, thus reducing needless energy loss.<ref name=":0" /> Furthermore, the amount of drag on the wing of the robot was reduced by the use of retractable wingtips thereby allowing for improved gliding abilities.<ref name=":1" /> Moreover, the leg of the robot was designed to incorporate sufficient torque after mimicking the anatomy of Pteryomini's leg using virtual work analysis.<ref name=":0" />

Following the design of the leg and membrane of the robot, its average gliding ratio (GR) was determined to be 1.88. The robot functioned effectively, walking in several gait patterns and crawling with its high DoF legs.<ref name=":0" /> The robot was also able to land safely. These performances demonstrated the gliding and walking capabilities of the robot and its multi-modal locomotion

'''Modeling of a multi-modal jumping and gliding robot after the Desmodus Rotundus (vampire bat)'''

The design of the robot called Multi-Mo Bat involved the establishment of four primary phases of operation: energy storage phase, jumping phase, coasting phase, and gliding phase.<ref name=":5" /> The energy storing phase essentially involves the reservation of energy for the jumping energy. This energy is stored in the main power springs. This process additionally creates a torque around the joint of the shoulders which in turn configures the legs for jumping. Once the stored energy is released, the jump phase can be initiated. When the jump phase is initiated and the robot takes off from the ground, it transitions to the coast phase which occurs until the acme is reached and it begins to descend. As the robot descends, drag helps to reduce the speed at which it descends as the wing is reconfigured due to increased drag on the bottom of the airfoils.<ref name=":5" /> At this stage, the robot glides down.

The anatomy of the arm of the vampire bat plays a key role in the design of the leg of the robot. In order to minimize the number of Degrees of Freedom (DoFs), the two components of the arm are mirrored over the xz plane.<ref name=":5" /> This then creates the four-bar design of the leg structure of the robot which results in only two independent DoFs.<ref name=":5" />

'''Modeling of a multi-modal jumping and flying robot after the Schistocerca gregaria (desert locust)'''

The robot designed was powered by a single DC motor which integrated the performances of jumping and flapping.<ref name=":7" /> It was designed as an incorporation of the inverted slider-crank mechanism for the construction of the legs, a dog-clutch system to serve as the mechanism for winching, and a rack-pinion mechanism used for the flapping-wing system.<ref name=":5" /> This design incorporated a very efficient energy storage and release mechanism and an integrated wing flapping mechanism.<ref name=":5" />

A robot with features similar to the locust was developed. The primary feature of the robot's design was a gear system powered by a single motor which allowed the robot to perform its jumping and flapping motions. Just like the motion of the locust, the motion of the robot is initiated by the flexing of the legs to the position of maximum energy storage after which the energy is released immediately to generate the force necessary to attain flight.<ref name=":5" />

The robot was tested for performance and the results demonstrated that the robot was able to jump to an approximate height of 0.9m while weighing 23g and flapping its wings at a frequency of about 19&nbsp;Hz.<ref name=":5" /> The robot tested without flapping wings performed less impressively, showing about 30% decrease in jumping performance as compared to the robot with the wings.<ref name=":5" /> These results are quite impressive{{Editorializing|date=July 2021}} as it is expected that the reverse be the case since the weight of the wings should have impacted the jumping.