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Asked — Edited

Determining When To Start & Stop Servos

I haven't actually started working on my project(s) yet, since I won't be getting my EZ-Robot until Christmas (if I was a good boy this year), but I am trying to learn as much as possible before then. I have two questions:

1. How can I determine the current position of the servo? When the code starts, the servo position is unknown, so I need a way to dynamically determine the position of the servo.

2. When using the grippers (I am hoping to get the Wild Thumper 4WD Chassis With Gripper), how do I know how far to close the gripper? Obviously not all objects are the same size, and the gripper needs to close enough that it can pick the object up, so how do we determine when the gripper is closed tight enough?

I don't know if this is the correct forum for these questions, but VB.NET is what I will be using for my projects, so I am posting it here. Thanks, any help would be appreciated.

PRO
Synthiam
#1  
Hi! Welcome to the community:) That will be an awesome christmas present!

1) The servo position is automatically set when you tell it. For example, there are hundreds of controls to move servos. But let's pretend you're just going to start off by using the Horizontal servo Control. If you slide the dial to position 25, the servo moves into that position. It doesn't matter what position it was in, it will move to 25. Position 25 is the same all the time, even when the power is cycled.

2) Your hand doesn't know how far to close either. When you think about picking up an object, the more you close your hand, the tighter the grip. So essentially, if you tell the servo to close all the way, it will put a great strong grip on the object. If it is a small object or large object, the grip strength will be different.

3) I don't know if you'll need to use VB.Net. Once you install ARC, i think you will be happy in that environment. ARC is pretty amazing:) And it's growing every week. It's an evolving peice of software. Browse the forum to see what people say about it, i think you'll be happier in ARC than VB.Net

Most of your questions will be answered when you begin using the kit. Browse the Tutorial section of this website and follow the steps. Each step has a video - watch the videos and it will help you understand what to expect.:)
#2  
Thanks, that definitely answers the servo position question. For the gripper, does that mean I should just always close it completely and then I will simply have the tightest grip possible? The reason I was asking about the gripper is because I didn't want to end up damaging the gripper by trying to close it too far.

I will probably be using ARC and VB.NET. The original reason I decided to ask for EZ-Robot is because I ran out of content and ideas for websites and apps, so I wanted some projects I could write code for (I have been writing VB.NET code for about 10 years), as well as a way to do something with my code that the rest of my family would find interesting. My plan is to test the basic components using ARC and then combine and convert them to VB.NET to add the more complex logic. Many of my project ideas, which include some ideas such as sorting colored blocks and solving a rubik's cube, involve logic that is probably too complex to write using anything other than an actual programming language, and I am the type of person that likes to have full control when doing things like this.

I have browsed the tutorial section, as well as done other searches, and have found many things that I expect will be useful, and I did assume many of my questions would be answered once I actually started doing everything, but I wanted to ask these questions now. I'm sure I will have other questions in the future as well (don't worry, I always do searches to try and answer them first), so thank you for your quick response.:)
Canada
#3  
Welcome @njsokalski

Yes, a nice Christmas present indeed!

As @DJ said, servos and, by extension, the gripper will just go or close where you "tell" them to go via software. What you are asking about is slightly more advanced technique called feedback. Just like the hand example, if we could not feel anything we would just open and close our hands based on how we "think" it in action, crushing an object instead of just grabbing it.

Thanks to EZ-Robot, getting feedback can be as easy to accomplish with sensor data like a potentiometer inline with the servo, or limit switches, etc... and the gripper pressure could be moderated with pressure sensing strips that return varying data back to the software.

Dive in when you get your kit and start with the basics first... the rest will come as you move forward. Over the years I have had a lot of theory and hands on tinkering, but it wasn't until I found EZ-Robot that I was able to quickly put my knowledge to practice and quickly built three simple robots in the last few months, I feel like a kid again (in a good way :P)

You will love this kit!:D
#4  
Are there any good sites you know of at which I would be able to buy a good appropriate sensor to use for that which would be compatible with the other EZ-Robot hardware? Obviously I have a lot to learn about this stuff (I've been doing software for almost 10 years, but this is my first big thing with hardware or robots). Thanks.
Canada
#5  
You could check out this LINK. Just one of many sites.:)

EZ-Robot uses "standard" ADC (analog to digital) inputs that measure voltage between 0-5v and the software registers that as 0-255. There are also Digital inputs and a I2C input.

Basically anything that works on an arduino should work with EZ-B... just easier:P
PRO
Synthiam
#6  
Beware of over complications. My moto is "Do more with less"

It's exciting shopping for sensors and features - but first start with the kit. Once you begin playing with the software and video processing, it is like a rabbit hole. And it's addictive, so beware of that too:)