Upgraded code and the Robot behaviour
The upgraded code for the wheel-legged biped robot in Simulink's Simscape environment uses PID controllers to control the robot's balance and stability. The controllers are connected to the revolute joint of each joint and wheel, with damping coefficients to consider their behavior. The setpoint values are fed into the controllers through a sum/subtract block to provide the correct feedback. The output of the controller is then scaled by a gain block to maintain the robot's stability, and the signal is connected to the revolute joint of each joint and wheel for realistic movement. An IMU sensor provides feedback, and three scopes display the feedback of the wheels, shoulder joints, and knee joints.
The ground plane is also designed to provide a realistic surface for the robot to move on, with spatial contact forces used to connect the wheels and joints to the ground. The dynamic and static friction of the ground and wheels are adjusted for realism, ensuring that the robot moves and balances realistically. Overall, the upgraded code provides a comprehensive solution for the robot's movement and stability.
Testing The Robot
To ensure that the upgraded code for the wheel-legged biped robot in Simulink's Simscape environment is functioning correctly and realistically, testing is essential. There are several testing methods that can be used to evaluate the robot's behaviour and performance.
Static stability testing involves placing the robot in a static position and checking its stability. By adjusting the setpoint values and PID controller gains, the robot's behaviour can be observed. If the robot is stable in a static position, it indicates that the control system is set up correctly.
Dynamic stability testing involves moving the robot to different positions and orientations to check its dynamic stability. By simulating various scenarios, such as walking or running, the robot's behaviour can be observed. The PID controllers can be adjusted to improve the robot's stability in different scenarios.
Performance testing involves evaluating the robot's speed, acceleration, and other performance metrics. By monitoring the system's performance, adjustments can be made to improve the robot's performance.
Friction testing involves measuring the resistance that opposes motion between the wheels of the robot and the surface it is moving on. This is important to ensure that the robot moves realistically and maintains its balance.
Impact testing involves subjecting the robot to impacts or shocks to evaluate its robustness. This is important to ensure that the robot can withstand real-world conditions and perform effectively.
Using a combination of these testing methods, the behaviour and performance of the wheel-legged biped robot can be evaluated and optimized for the desired application.
Wheel PID Controller
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When working on the wheel-legged biped robot's upgraded code used the confirmed dynamics to apply PID controllers to control the robot's stability. With the help of their supervisor and co-supervisor, they adjusted the PID values and used feedback from the scopes and calculations to fine-tune the robot's behaviour. They were able to successfully get the robot to oscillate briefly before balancing itself using only the proportional gain value. The PID controller is a vital component in robotics, which helps to maintain stability and control by continuously adjusting the system's input based on sensor feedback. It's crucial to adjust the integral and derivative gain values in conjunction with the proportional gain value to fine-tune the system's performance. A higher proportional gain value results in faster response times, but it can also lead to overshooting and instability. The individual made significant progress in optimizing the PID values for the wheel-legged biped robot and achieved stable behaviour by balancing it using only the proportional gain value, which is commendable.
Joint PID Controller
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In a wheel-legged biped robot, the shoulder and knee joints play a critical role in maintaining the robot's balance and stability during motion. To ensure that the joints remain in their correct position, setpoint values are given to each joint. PID controllers are then utilized to adjust the joint angles to reach and maintain these setpoints.
The PID controllers receive feedback from sensors that detect the joint angles, and then adjust the joint angles as necessary to reach and maintain the desired setpoint values. The feedback from the PID controllers is shown in graphs , which confirms that the robot is in its stable position.
By using PID controllers in this way, the robot can remain in its normal mode without extending or retracting, ensuring that it is stable and able to move in the desired manner. This is critical for maintaining the robot's balance and stability while it is in motion, as any unwanted extension or retraction of the joints can lead to instability and loss of balance.
The setpoint values and PID gains can be adjusted as necessary to achieve the desired level of control and stability for the robot. This is important as the desired level of control and stability can vary depending on the specific application of the robot. For example, a robot designed for rough terrain may require a higher level of stability and control compared to a robot designed for smooth surfaces. Therefore, adjusting the setpoint values and PID gains based on the specific application of the robot can result in optimal performance and stability.
