Arushi – This week my goals consisted of combining my image processing code with Shreyas’s pid/robotics program to try to start testing our project and refining it for our midpoint demo. We initially had difficulties with a lag in our camera which was fixed by changing a while loop in our code to a for loop that sets a parameter for the pi camera. Once we fixed that, we were able to test rotations in place by moving our target around in a circle around the robot. We had difficulties, however, with the image processing sometimes picking up the top of the door to the room as having hsv values within the threshold range for our target. We tried adjusting the hsv threshold accordingly, but were still having troubles. For possible solutions, I wrote out programs that 1. involved an rgb threshold instead of hsv -> for which we were having troubles identifying the circle under a shadow and 2. changing our target to a chessboard and using a opencv builtin for finding chessboard corners. The chessboard was accurately being picked up, but similar to other HOG based algorithms, it was too slow when it was implemented on the pi. Right as we started to print a new target for which we could specify the hsv, when coloring it, Shreyas tried a threshold that worked. We then were able to test the individual aspects of in-place turns and moving straight. At the end of class we were able to put the parts together. The goal for next week is to further smooth out the PID, connect the pi to a battery source and then test in a variety of lighting to ensure that the image processing does not pick up parts of the image that are not the target.
Shreyas – This week I worked with Arushi on integrating different image processing algorithms into the Raspberry Pi. To avoid repeating details described above, I will talk more about the robot control module side of it. I started with tuning the PID for the X displacement part to make sure rotations were smooth. After this was tuned and after a better image processing technique was found I added logic to find the z displacement based on the area of the target. Then I got the PID controller to also work on the Z displacement part so movement forward and backward was also smooth. The last and most challenging part on my end was figuring out how to move the robot in both the Z and X direction. Since I am sending raw motor power commands based on the output of the PID controller, currently it is not possible to move in the Z and X direction in the same time. The main limitation right now is that the PID controller calculates the motor values independently of each other. Next week I am going to work on having the PID controller give a combined output of Z and X displacement so that movement in both degrees of freedom is possible. However another concern is that may damage the motors. Since the iRoomba is a pivot based robot, sending two different power values to the left and right motors (for curve motion) would put stress on the motors. However for slightly different magnitudes this shouldn’t be a problem. This is something that takes careful testing. Next week my goal is to integrate the iRoomba’s sensors and tune the PID for bi-directional movement.
Pallavi – This week my goal was to get the serial communication between the arduino and the raspberry pi set up. I unfortunately did not complete my goal because I ran into some issues setting up the serial communication on the raspberry pi zero. I’m running a simple python script on the pi just to check whether I can write to the terminal. When I try this, however, the program simply hangs. I looked at this link (https://www.raspberrypi.org/forums/viewtopic.php?t=180951) and made sure to implement all the solutions discussed. However, my raspberry pi is still not printing out to the terminal. I’m going to work with Shreyas on Monday to figure out what the issue is.
Other than setting up the Pi, I was looking up doing tx, rx communication versus usb communication between the arduino and raspberry pi. I ended up going with tx, rx communication because of less overhead compared with usb communication. I also had to set up the simple voltage divider to properly connect the raspberry pi and arduino, as the raspberry pi has a 3.3V tx and rx pi while the arduino has 5V pins.
This week, I hope to get the serial output working on the pi to ensure I can test my arduino code. I also hope to start integrating my sensors with the combined iRoomba and object detection Shreyas and Arushi have been working on this week.