Development of a 3D-printed biped robot with distributed joint control

Biped robot research is currently undertaken by the Robotics and Automation Laboratory. The project is broadly divided into three parts: the mechanical design, electronic design, and control design. The biped developed was a 10-DOF robot. The parts were modeled using Solidworks software. After being modeled, the parts were then 3D printed and lasercut. DC motors with built-in encoders were acquired for joint control. Each of the six joints (right and left ankle, knee, and hip) had its own joint controller board with a microcontroller and one/two motor drivers, connected using controller area network to a master controller. The joint controllers control the motor using PWM, and read the joint positions through the use of incremental hall-effect encoders. They also implement a proportional-integral-derivative (PID) controller. The step response of each joint was tested. It was found that the rise time and settling time of each joint was adequate for the task, less than 250 ms and 350 ms respectively. The biped robot was also tasked to follow two trajectories. The maximum position error for any joint was two degrees, with steady-state errors less than 0.5 degrees. In the future, the biped robot could be used for future research, with the addition of appropriate sensors (such as pressure sensors on the feet or an inertial measurement unit).