Autonomous Systems (A&K Robotics) CTO Lingkang Zhang has built over a dozen robots throughout the years that range from bipedal and quadruped to rovers and drones. His latest creation is Quadruped Robot Tsuki — an ROS-enabled, highly dynamic robot that's based off his previous quadruped (Kaze), only it’s stronger, faster, and more robust. It’s also wholly position controlled, with no contact sensors on its feet, or any IMUs for that matter.
Tsuki was designed using Fusion 360, has 12 degrees of freedom, and is equipped with 12 RDS3135 servo motors that serve as actuators for the 3D-printed legs, which also feature metal shock absorbers/dampers to help reduce the amount of torque required to actuate each leg. A 3D-printed torso reinforced by several carbon fiber tubes makes up the body of the robot, which houses all the necessary hardware that drives Tsuki.
Tsuki's motor driver system consists of an Orange Pi Zero Plus 2 for overall control, and an Arduino Pro Micro with Adafruit PWM Shield to convert the signal from the Pi to drive the servo via I2C.
On the software side, Zhang explains, “No IMUs or foot contacting sensors are used at the moment. All the control is simply “position control,” not force control involved. The basic idea is to imagine the four legs are four robotic arms and take turns to lift up or move forward. ROS is being used for the high-level control.”
Zhang says he may open source the code he used for Tsuki at some point in the future, but those interested can check out a similar solution he created for his earlier Quadruped 9g robot.