I am seeking to ascertain whether there are any issues with a servo having an angle of 120° to 140°? This is due to the fact that the shopping list specifies a servo with an angle of 180°.
For a simple walking gait, it only needs about 90 deg. of movement. If your servos have a smaller range, you may have to adjust the angle that you mount your servos so that the zero angle is at the average servo angle.
I need confirm one thing. While assembling all your servos are set at zero right? Do you set the min and max limits for the servo in program right? I asked because for the shoulder it need to not be set at zero while assembly but 90 degrees. How do tackles this program? Cause if you don't they legs will break upon sweeping it the full 180 degrees the way you've assembled it. Also what program I need to run in the repo to make it walk? and Also I just have PCA9685 and RaspberryPi. What changes do I need to make? Thank you!
By zero, I mean 90 degrees. It is about your frame of reference. Servos have a 180 degree arc which can be viewed as 0-180 or -90-0-90. In the latter, 0 would be equivalent to setting the servo to 90 degrees. You can use a different angle as your 0 position, but the joints will need to be mounted according. The min and max limit are set in the program. I currently don't have any programs in the repo to control the robot, however, you can look at "locomotion_test.py" to see how to make the robot move. I still need to work on a video for how to control the robot. The servo hat that I am using also uses the PCA9685 chip. It should work, however, I found that it struggled to carry enough current to the servos. I had to solder some extra wires from the power terminal to the servos to bypass the small trace wires on the PCB. Hope this helps.
Any 2S lipo will work. I use a 2200mAh battery so that it will be small enough to fit inside the chassis. I decided to use: amzn.to/3WTydp2 (Affiliate link) I bought servos that can run at 7.4V so I could just route the battery power directly to the servo controller. My servo controller had a MOSFET in the circuit that couldn't handle the 7.4V. I had to solder on some extra wires to circumvent the MOSFET and directly connect the input voltage to the servos.
Good question! I'm a big fan of Python. For this project, I used jupyter-lab and set it to be launched when SpotMicro boots up. This allows me to edit and run the code from a web browser which made development very easy.
You're right. Python is a slow language. I'm just using Python for its convenience. What I've seen people do in the past is use Python to develop their algorithms then transcribe them into a faster language such as C++. That way you get the best of both languages. I take it that you're a C sharp developer? Have you ever programmed robots using C sharp? What was your experience like?
@@AdvancedHobbyLab no I m not developer . I studied Python beginner but I m suggested to study c sharp for future . I m mechanical designer , i like apr and robot dog
You have to make sure the voltages match. Most servos are only rated for 5V. In this build, I used 7.4V directly from the 2S lipo. You also have to make sure the servo horns match. I used the parts for "SpotMicro V2" that uses PDI-6221MG servos so it won't fit MG995 servos.
I'm glad you like it, however, I have no plans to use an arduino. You can find the github repo here: github.com/AdvancedHobbyLab/SpotMicro/tree/main. The code is written in Python, but perhaps it could help you with arduino code.
