May 30, 2008 Creating robots that can replicate the locomotion and maneuvering skills of insects is an increasingly attractive project for scientists – it lends itself to simple prototyping, and has obvious applications for surveillance, exploration, search and rescue assistance, and sensor deployment. While the EU-funded SPARK initiative is attempting to replicate the cognitive processes of bugs, researchers at the Laboratory of Intelligent Systems at EPFL have developed a jumping robot inspired by the grasshopper.
The 5cm model uses a 0.6-gram pager motor and a cam to charge two torsion springs, which trigger a jump from the robot’s 1.3mm carbon rod feet. The 7-gram robot can jump 1.4 meters, more than 27 times its body size, and ten times the distance of any existing jumping robot. The robot incorporates an infrared receiver and a 10mAh Lithium Polymer battery, which the researchers hope can be reduced in size to further decrease the weight of the model. The motor recharges the mechanism for one jump cycle in 3.5 seconds, using 95mA. The 10mAh provided by the LiPo battery theoretically allows for 6.3 minutes of continuous recharging or approximately 108 jumps. "This biomimetic form of jumping is unique because it allows micro-robots to travel over many types of rough terrain where no other walking or wheeled robot could go," explains EPFL Professor Dario Floreano. "These tiny jumping robots could be fitted with solar cells to recharge between jumps and deployed in swarms for extended exploration of remote areas on Earth or on other planets."
The four bar linkage leg system enables researchers to adjust the jumping force, take off angle, and force profile during the acceleration phase. The amount of energy that will be stored in the springs can be adjusted by changing the spring setting between 106mJ and 154mJ in steps of 6mJ.
The reason a jumping mechanism is so valuable in small robots is because the smaller a body is, the more difficult terrain becomes to navigate – a principle known as the “Size Grain Hypothesis”. Jumping is a power-efficient way for a robot to overcome large obstacles and traverse wide areas of land in a short amount of time. With future models, the researchers hope to include a set of folding wings, so the robot can glide back to Earth from the apex of its jump.