Session: 15-01-01: ASME International Undergraduate Research and Design Exposition

Paper Number: 145294

145294 - Design and Development of Leo: An Affordable Biomechanically Inspired Quadruped Robot With Cognitive Abilities 

A significant portion of land, be it indoors or outdoors, is inaccessible to existing wheeled and tracked vehicles. But people and animals using their legs can go almost anywhere. As a result, legged robots are gradually becoming a promising solution for navigation through rough terrain and stairs. With the MIT Cheetah and Boston Dynamics Spot, lots of advances have already been made toward quadruped robots.

The main contribution of this work is the development of Leo - a lightweight and affordable quadruped robot that resembles the movement of a dog. In addition, Leo's voice and image recognition abilities make it a talking dog, allowing it to mimic the behavior of pet dogs that serve as dear companions to humans.  

The whole design, limb arrangement, and locomotion of Leo are biologically inspired. Leo’s body consists of four legs and one spine. Each leg has 3 degrees of freedom, which requires 3 motors per leg to control the movements. The spine of the robot acts as a support for the legs and the weight of the body, which is the battery, and also provides space to house and streamline the electronics. The design of the legs is crucial for ensuring the overall stability of the structure and required maneuverability. Each leg consists of a shin and a thigh. A crank-shaft mechanism is used in each leg to ensure the forward movement of the whole body. The thigh consists of three motors, one is directly attached to the spine, another one ensures the pitch movement of the leg, and the remaining one is connected to the crank-shaft. The reason for using a crank-shaft mechanism is to minimize rotational inertia because the servo is placed on the upper side of the thigh. This ensures reduced power requirement and ease of movement of the whole body. Additive manufacturing is used to manufacture all the structural parts of the robots. Specifically, fused deposition modeling (FDM/FFF), known as 3D printing, was used to manufacture all the parts, which greatly optimized the production cost. As material, PLA (Polylactic Acid) was used to manufacture all the legs of the robot, because of its low weight for volume and lower print temperature.

The motion control is achieved through ROS (Robot Operating System) - Arduino interfacing, utilizing the gait algorithm developed. Upon startup, calibration of the 12 servo motors across four legs of Leo is performed to allow it to stand properly. To determine the 3D coordinates of each leg, trigonometric calculation was used following an elliptical pathway to emulate the natural gait of a quadruped. Upon receiving the motion commands over the Bluetooth module, the gait algorithm determines the angle of rotation for each of the legs to obtain the desired position of legs required for standing, walking, and dancing. The communication system of Leo integrates real-time image and audio processing, supplemented by ROS Arduino interfacing. To understand its surroundings, Leo uses YOLO v4, a cutting-edge real-time object detection system analyzing the video data captured by the head-mounted camera. It is also able to communicate verbally using the audio module. The audio is detected by the on-board microphone. After noise suppression, the audio is converted to text by the vosk node for ROS. The text is then fed to the ChatGPT API which enables Leo to respond to virtually any query, qualifying it as a companion bot. The communication system enables hazard detection to prompt gait adjustments as needed.

To ensure the accuracy of the findings, checks were conducted on Leo’s object detection performance. Furthermore, the effectiveness of the gait algorithm was evaluated by analyzing the knee angle and tracking changes in the body's center height over time.

Presenting Author: Jubaer Tanjil Jami Bangladesh University of Engineering and Technology

Presenting Author Biography: Senior Year Mechanical Engineering Undergrad.

Authors:

Jubaer Tanjil Jami Bangladesh University of Engineering and Technology
Taskin Mehereen Bangladesh University of Engineering and Technology
Mir Tahmidur Rahman Bangladesh University of Engineering and Technology
Munirul Alam Bangladesh University of Engineering and Technology