  Designing a mechanism to mimic the motion of a common house gecko is the
objective of this work. The body of the robot is designed using four five-bar
mechanisms (2-RRRRR and 2-RRPRR) and the leg is designed using four four-bar
mechanisms. The 2-RRRRR five-bar mechanisms form the head and tail of the
robotic lizard. The 2-RRPRR five-bar mechanisms form the left and right sides
of the body in the robotic lizard. The four five-bar mechanisms are actuated by
only four rotary actuators. Of these, two actuators control the head movements
and the other two control the tail movements. The RRPRR five-bar mechanism is
controlled by one actuator from the head five-bar mechanism and the other by
the tail five-bar mechanism. A tension spring connects each active link to a
link in the four bar mechanism. When the robot is actuated, the head, tail and
the body moves, and simultaneously each leg moves accordingly. This kind of
actuation where the motion transfer occurs from body of the robot to the leg is
the novelty in our design. The dimensional synthesis of the robotic lizard is
done and presented. Then the forward and inverse kinematics of the mechanism,
and configuration space singularities identification for the robot are
presented. The gait exhibited by the gecko is studied and then simulated. A
computer aided design of the robotic lizard is created and a prototype is made
by 3D printing the parts. The prototype is controlled using Arduino UNO as a
micro-controller. The experimental results are finally presented based on the
gait analysis that was done earlier. The forward walking, and turning motion
are done and snapshots are presented.
