This is my first post to the SimpleFOC forum.
About myself: I am a retired teacher living near Brisbane, Australia. I am an amateur machinist and mechanical designer. I can make most things mechanical. I am very weak concerning electrical things tho I have done some work with RaspberyPi and Arduino.
My Project: I am attempting to make a biped walking robot. I now have the robot walking smoothly supported by a wheeled frame. Stability fore and aft is very good. Stability left and right (laterally) is zero. I want to use a reaction wheel to provide lateral stability.
I found the YouTube video " Arduino Reaction Wheel Inverted Pendulum" and was impressed that this might provide a solution to my stability problems. My first task is to buy the necessary hardware. This is what I have found so far on Ebay:
Controller: Simplefoc shield v2.0.3 FOC BLDC servo motor controller
Motor: MKS sF2804Brushless motor
Encoder: MKS AS5600encoder
Computer: Arduino UNO
Please refer to: https://www.youtube.com/watch?v=_sG-DOzc5R8
Question: Are the above motor and encoder up to the task of making a reaction wheel using the SimpleFOC library? If not what would you suggest?
Apology: Basically I am a hobby machinist and mechanical designer. I know next to nothing about electronics and coding. From my experience on other forums dealing with machining, clocks and gear driven mechanisms I know how frustrating is can be to deal with novices that ask very basic questions. I wish to not annoy and I apologize. Please point me in the right direction to get started. I think the potential for Field Oriented Control for makers/hobbyists is great.
Thank you in advance for any help you might be able to give. When I make progress I will share with the forum
Welcome to the forum, what you describe sounds awesome.
Let’s wait for someone more knowledgeable than me to input.
Seems possible, I believe.
Do you need only lateral stability or stability in X-Y?
Thank you Valentine,
X-Y stability is pretty good, only need lateral stability.
Using an inverted pendulum requires an immovable pivot point. Bipedal motion doesnt have such pivot point. Your only choice would be to attach the flywheel to the center of gravity of the mechanism and somehow hope the legs provide enough leverage, but the legs would be moving. Also the flywheel must be huge, weghing perhaps as much as the mechanism to provide sifficient momentum. Which means the motor must be huge, too, and i have not seen gimbal motors large enough to power human sized flywheel.
how big is the biped? are we talking toys or a life sized biped? The biggest gimbals on the market barely go 10 kg/cm. May be 20 if you are willing to spend $$$$.
Thats a hard problem to solve.
Great comments, thanks.
Size of the robot is 45 cm from bottom of foot to the hip joint. No upper body at this time. I have placed the legs close together, 45 mm width at the hip joint and the center of the right and left foot strikes are about 50 mm apart. I have tried to get the hip joints and foot strikes as close together as I can to reduce lateral movement. One foot is always in contact with the ground and the legs swing in a rolling motion, front to back. In “theory” the leg in contact with the ground is like a bar going from the ground up to the hip joint. I am hoping this provides the immovable pivot point you mention.
Though true, it is not entirely how some people work. Many people have sufficient experience and capacity to perform subconscious modelling and commit to material a decent working model. And then perform variations of the model to fine-tune the empirical result until it works to their satisfaction. We shall not discount the ability of people to use mental models which are sometimes all needed to commit to material.
Two very good comments from Axe and Valentine. I do respect and admire Axe’s approach and acknowledge his method is the right thing to do. (Thank you for the software recommendations.) Yet Valentine speaks more to the “art” of invention and problem solving. I wish I had more of Axe’s ability but I do not. So I will most likely fail in my little project but I am having fun and have made some little progress. I like making things. I’ve made more junk than good stuff but I keep learning.