This project aims towards the design and the development of the robotic legs, and testing the same against the environmental constraints(different terrains), the Torque bearing capacity, the load as well as the shock bearing capabilities of the legs of a Quadruped Robot. So basically designing, manufacturing, testing, and controlling of leg for a quadruped is to be done in this Project. Further we will utilize CAD modeling software such as SOLIDWORKS, ONSHAPE, or FUSION360, depending on their preference, to assemble the quadruped meticulously.
A quadruped robot is a type of robot that walks on four legs, mimicking the movement and structure of four-legged animals. These robots are designed to navigate various terrains and maintain stability, making them useful for tasks that require mobility over uneven or complex surfaces. Quadruped robots are commonly used in research, exploration, rescue missions, and other applications where traditional wheeled robots may struggle to operate effectively. The development of quadruped robots involves advanced studies in areas such as robotics, biomechanics, control systems, and artificial intelligence. They often feature sophisticated sensors and algorithms to enable precise movement and adaptability to changing environments.
Firstly, the basic concepts of the project needs to be cleared. Quadrupped is advantageous, but how can we approach and make it? What are the pre-preparation for the same? We just need to undergo the previous research papers on the Quadraped Robots, have a basic understanding of the mechanisms we need to drive the upper and lower leg links, get abbduction as well as adduction , have a basic knowledge of materials ,the Leg modelling and simulations as well. Then comes the manufacture part and the various tests
As the name suggests, the leg design is quite an essential part of the bot, and a flawed design will destablize the entire bot. This would end up hindering the functionality of the bot. To avoid this, we first went through a pen and paper phase of designing the legs, each mentee coming upn with two designs. Then, we chose a total of 3 from these, that seemed to be perfect to move forward with. The, we proceeded to create CAD models of these 3 designs.
This is what the final leg design looked like:
The material which we are going to use for the leg is Aluminium and for the the support is PLA
Before sending the CAD models for manufacturing, it is necessary to analyze the forces acting on the leg and their corresponding effects on it. Also, it is important to take into account the stress, strain and the resulting deformation due to these forces. For simulating this, we used a software called Ansys. Here, we could add the various force vectors acting on the leg and find the resulting deformation, stress and strain on the leg.
This provides us with an insight about the potential problems that might arise after manufacturing; which would lead to economical loss. By simulating almmost realistic forces on the leg and studying the results, we can alter the design and prevent such losses.
In robotics and control systems, an actuator is a device responsible for moving or controlling a mechanism or system. An actuator takes energy, typically electrical, hydraulic, or pneumatic, and converts it into mechanical motion.
Types of Actuators:
Linear Actuators: Produce motion in a straight line, commonly used for pushing, pulling, or lifting.
Rotary Actuators: Produce rotational motion, typically used for rotating or spinning parts.
After the leg design, we needed a torso that would be able to support the legs, completing the body of the quadruped robot. For this, we created a simple design that would be able to be the body of the bot.
URDF (Unified Robot Description Format) is an XML format used in ROS (Robot Operating System) to describe the physical configuration of a robot, including its joints, links, sensors, and actuators. Gazebo is a powerful robot simulation tool that integrates with ROS, providing a realistic physics engine and 3D environment for testing and developing robotic systems. When a URDF file is loaded into Gazebo, it defines the robot's physical appearance and movement, allowing the simulation to accurately represent how the robot would behave in the real world. The URDF file serves as the bridge between ROS and Gazebo, ensuring that the robot's model in the simulation matches its real-world counterpart.
The notes and Force Calculations
Inverse Kinematics (IK) is key to controlling the quadruped’s leg movements. It calculates the joint angles required to position the foot at a specific location in 3D space.
Our leg consists of:
Hip Joint: Controls horizontal and vertical orientation. Knee Joint: Bends the leg.
How It Works
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Input: Target foot position [x,y,z].
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Calculation: Joint angles are computed using trigonometric relations.
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Output: Angles are used to move the leg to the desired position.
The motor control system is responsible for driving the quadruped's leg joints, ensuring precise and coordinated movements.
Each leg is controlled by three stepper motors:
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Abduction Motor: Controls the sideways movement of the leg.
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Upper Leg Motor: Manages the movement of the upper leg.
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Lower Leg Motor: Controls the bending of the lower leg.
These motors are driven by three stepper drivers, all connected to a single ESP32 microcontroller.
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Laser cutting and 3D printing of parts.
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Implementation of gait in simulation.
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Physical Assembly of Titan and Real-world Gait Testing.