VEX EDR V5 Robot
Hoping to gain results as to how different pill capsules would behave in astronauts we designed this chamber to be sent into space. Conceptualized and designed in a team of 12 people, over 1 month, we worked together to develop the chamber as well as the experiment that will happen within.
Algorithms
Odometry
Odometry is a method used to estimate the current position and orientation of a vehicle or robot by measuring and integrating the changes in its motion over time. It tracks movement based on its wheel rotations, sensor data, and alternation motion-related information. In our case, we made use of 2 elastically restrained tracking wheels placed at measured locations to have a better understanding of our true displacement within the field. These wheels are connected to two individual wheel encoders which along with the location of the wheels and size of the robot, calculate the distance and direction of travel, consequentially updating the position and orientation. However, Odometry also comes with some downfalls, one of which is odometry drift. This is when environmental factors can cause the tracking wheels to drift displacing the measured distance. To combat this, we used an Inertial Measurement Unit to measure gyroscopic values and acceleration. Overall this mitigated measured drift and improved the accuracy of our position tracking software.
PID Controller
A Proportional-Integral-Derivative Controller, other known as PID, is a control algorithm used in robotics for the sake of process control. the PID controller regulates movement speed based on given information and sensor values. In our case, we used the PID controller to control movement speed and achieve precise motion during the Autonomous mode. This aside our position-tracking algorithm allowed us to navigate to any point on the field as long as we have known coordinates.
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Proportional Component
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This term is meant to compute an output based on the current error. The error is the difference in travel distance and displacement. Using the error the proportional component calculates the velocity at which the robot must travel. The larger the error, the greater the velocity.
Integral Component
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The integral term takes past error values and uses them to estimate a velocity adjustment. This component helps to mitigate any issue from factors like friction, motor bias and environmental interference. This was important for us as our motors and wheels were prone to bias and drift.
Derivative Component
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The derivative component takes the rate of change in error as the robot moves along the path. This is important as it is used to predict future errors, allowing for speed adjustments prior to any issues occurring. This is important in reducing velocity enough to prevent any overshooting or oscillations from occurring.
Vision Tracking
Vision Tracking is the process of using cameras to follow and monitor the movement of objects or targets within a visual scene. In our case, we had to employ visual surveillance to find coloured objects within the game field.
Sensors
Rotary Encoders
These sensors are measured in continuous rotations with 360 ticks per revolution. These sensors were employed to measure the number of revolutions the tracking wheels make as they move across the floor.
Inertial Measurment Unit
This sensor was used to measure displacement in the Yaw axis for the sake of autonomous movement. It was used for turning as well as maintaining movement along a straight line.
Optical Sensor
Capable of distinguishing colours across the RGB spectrum, this sensor was used inside the robot to read the colour of the balls as they were fed into the storage chamber.
Field Camera
After training the camera using the VEX software, it was capable of tracking similar objects as well as returning key values such as location and colour.
