Mechatronic frog, a robot that can leap

Ramani KANGARAARACHCHI

The Uva Wellassa University (UWU) is the first entrepreneurial University in Sri Lanka known as the Centre of Excellence for value addition. It fulfills the requirement of producing undergraduates with entrepreneurial skills much needed for the country. This is the ninth of a series of articles based on final year student research reports on value addition which will be useful for industrialists as well as readers. The objective of this series is to encourage and introduce the country’s future entrepreneurs to make industrialists and other relevant parties aware of potential businesses. Interested parties can contact the University for more details

Nimesha Wijesuriya

Priyanwada Nimesha Wijesooriya, is a final year student who has specialized in mechatronics in the science and technology degree program. She is a past pupil of both Viharamahadevi Maha Vidyalaya and Girls’ High School Kandy. The Uva Wellassa University has helped her to realize her childhood ambition to be an inventor.

She has developed a jumping robot called the ‘Mechatronic frog’. The project was carried out as her final year research project to construct a mechanical robot that can jump to move in a rough terrain.

Robotics is a vast area which leads to many research to develop its concepts and seek out possibilities for many unsolved problems. Robots locomotion is one of these hot topics. In many robotic applications there are classical locomotions such as wheeled robots, tracked and legged robots. But these applications face many problems when exposed to rough outdoor terrains.

Jumping robots can jump over larger obstacles compared to its size. The main advantage of a jumping robot is, it can avoid large obstacles by jumping over them. So the jumping robot is a good solution to very advanced industrial robots in the fields of interplanetary explorations, agriculture, biology and even for military purposes like spying.

A biometic solution

Jumping is a biomimetic solution to an effective locomotion. It is concerned to be effective and robust locomotion type for robots that work on rough environments. It is a method of amplifying energy and obtaining high power from a small amount of supplied energy.

Energy is stored for a short period of time in elastic elements which is utilized lately in order to make an effective jump. The punching press and fly wheel are also based on a similar concept.

The robot developed has four spring loaded legs. Spiral springs were used as elastic elements to store energy. To load and unload the springs a drop cam mechanism was used.

It is actuated using a 12 volt simple DC motor that is powered by a 12 volt battery.

After initial construction the robot was tested in an outdoor environment. Then found out that it is capable of jumping continuously while maintaining its stability. The number of jumps is basically depending upon the battery capacity.

At the development process many mechanism were tested and final solution was selected, which maximize the energy efficiency and the trajectory.

Many other jumping robots have already been made using very expensive but suitable, less weight material and efficient small size motors. These robots were inspired by various jumping animals such as locust, gorilla, frog and human . These robots designs are based on several methods and material to store energy. Such as coil spring based designs, fluid powered designs, bending spring based designs, momentum-based designs, and elastomer-based designs.

The jumping robot

This robot is a coil spring based design. Most of these robots are micro type robots which deliver better performance due to low weight and smaller size.

But this robot was developed using junked items which can be easily found on local junk yards. It weighs only 1.5 kilograms. The materials used for the structure were made of aluminum and plastic.

Most of the body components were made of aluminum while other necessary parts were made from iron. To implement this prototype basic knowledge was obtained mainly by observing hoping of different creatures.

The activation of the robot is a step wise process. First the springs of the robot’s hind limbs are loaded.

Then they are released quickly applying sudden thrust on the ground. From this external impulse force the robot gets energy to jump.

The main point considered here was distribution of weight over the robot platform. Because it directly affects the stability of the robot specially when landing from a jump.

Further work

Wijesuriya’s next target is to increase the jumping distance of the robot and to add a sensor system to detect obstacles so the robot will be intelligent enough to adjust jumping distance and height in order to avoid obstacles.

These types of robots can be applied for planetary exploration projects, environment monitoring systems and robots for security purposes.