Page 73 - Amphibionics : Build Your Own Biologically Inspired Robot

Amphibionics 04 3/24/03 8:23 AM Page 52
FIGURE 4.1
A tree frog and its
biologically inspired Amphibionics
robotic counterpart.

tion is achieved by releasing the energy stored in the frog’s hind
legs. Figure 4.1 shows a tree frog, along with its biologically
inspired mechanical counterpart.

Overview of the Frogbotic Project

The robotic frog to be built possesses two spring-loaded hind legs
that are used to achieve locomotion by jumping, as shown in
Figures 4.2 and 4.3. The functions of the leg mechanisms, sen-
sors, and leg position limit switches are controlled by a Microchip
PIC 16F84 microcontroller.

The spring of each leg is independently loaded with a mechanism
that uses a standard servo, modified for continuous rotation. A
close-up of the spring-loading mechanism is shown in Figure 4.4.
When the servo is rotated to the position where the cam-like
device is fully set and the spring is loaded, a limit switch is trig-
gered. At this point, the microcontroller stops the servo and holds
this position until both legs are in jumping position.

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