Nowadays, servomotors are classically used as actuators to drive small legged robots. Their advantages are numerous: simplicity of control, miniature size, and a large choice of dynamic models, which allows to choose the best compromise between speed and torque for the robot joints. However, the main disadvantage of servo motors is their permanent energy consumption, due to the permanent effort needed to keep the angle of the joints constant, e.g. when the robot stays in place. In addition, the dramatic heating of the servo motor housing and gears can lead to their breakage, thus compromising the locomotion of the robot.
The objective of our work in hexapod robotics is to design a new energy-efficient robot leg for fully 3D printed hexapod robots. The principle of the structure of our new leg is based on an irreversible mechanism inside each joint (an actuated screw-nut system), which will considerably reduce the energy consumption of the robot, approximately by half, compared to our earlier version powered the AntBot hexapod robot. The design of this new leg is directly inspired by the structure of insect legs. In return, it will provide biologists with an efficient robotic tool to test both ant locomotion pattern and insect navigation over long distances without the limitations of servo motors.
At the end of this project, a hexapod robot with low energy consumption will be built to travel a few hundred meters in outdoor conditions compared to only a few dozen for the AntBot. The servomotors will be replaced by screw-nut systems, and the joint forces will be measured to determine the force of reaction to the ground, which will allow the robot to evolve on sloping or rougher grounds, but also to generate patterns of asymmetric locomotion as ants do to vary the robot’s course in real time depending on the task to be performed.