We will definitively do more event like this! (September? October? be ready …)

I did this shot in Los Angeles, last year. I took me thousands of shots before this one, hopefully this guy was there…

Next photo features Julien on the same beach (thanks Julien)…

3D CAD Model

We found many wheeled robot on the market, but nothing corresponding to our goals. So, we decide to design the one we want. On a previous post, Bilock introduced the Scalpel project. Here is more details about the Scapel’s mechanic design.

Our robot must be :

• Android based
• Fast, precise and responsive
• Fully autonomous
• Robust and easily assembled

We try to keep the design modular, so you could use this robot locomotion in your own project.

For each topic introduced here, I tried to give a theoretical overview combined with some manufacturing details. I would also try to give you tip and trick to create your own robot based on this scalpel kit. Later, with the scalpel team, we will take a confrontation between the theoretical analysis and experimental results.

Capacities of responsive and accurate displacements

The first step is to determine the mechanical characteristics of the robot’s locomotion. The reactivity of the platform is directly connected to the acceleration and deceleration capabilities without loss of grip. We will see the importance of choosing wisely the coordinates of the center of gravity and the importance of the grip between wheels and the ground.

The electric motors

Then we explain the motor choice to achieve the desired performance. We will detail the operating characteristics of a DC motors and the importance of specific power supplies. Electric motors for our robot, are controlled by PWM command. We will describe the signal command characteristics to optimise the locomotion precision and reactivity while securing the hardware against possible damage.

The control systems of rotary sensor wheels

Odometric wheels are use to estimate the position of a moving robot. This system is generally made by wheels connected to rotary encoders. Encoder are generally directly linked to the motor, but this assumes that the wheel is permanently in the contact with the ground and the friction is perfect. Here we explore an original solution of a decoupled odometric wheels. Encoders that are available on the market are expensive and the mechanical integration of this decoupled wheel is not trivial. I would show how, using an Hall effect sensors “1024 increments per revolution” and the minimum number of mechanic parts, that it is possible to manufacture a robust encoder wheel for an affordable cost.

Systems of perceptions by IR sensors

Since we want this robot being autonomous, we need to use efficient obstacle detection sensors in order to avoid obstacle collision. As a first step, we integrated the famous Sharp GP2D120. I know that software developers are never happy, they always want to modify the IR sensors angle but the Sharp senors packaging do not allow rapid orientation of the sensors. I will detail the mechanical changes I did on the Sharp infrared sensors packaging to allow my “never satisfied” friends to change quickly the sensor orientation.

]]> http://ognacgnouc.com/2012/03/mechanical-design-of-a-mobile-robot/feed/ 0 http://ognacgnouc.com/2011/12/collective-writing-using-twitter/ http://ognacgnouc.com/2011/12/collective-writing-using-twitter/#comments Thu, 01 Dec 2011 23:37:59 +0000 BiLocK http://ognacgnouc.com/?p=391 Read the Rest...

http://www.youtube.com/watch?v=DEziMqYbpEs

Scapel 1,5kg proto - Side view

Since few weeks I’m playing with the IOIO Board during my off time. This project is designed to be connected to a Android phone.

The target of this project is to create a high precision 2 wheels robot driven by an Android phone and release as an open source project. I call it the Scalpel. Max speed will be around 2 meter/second and positionning is done by 2 fully independent odometric wheels and distance sensors (sharp gp2d120). Weight will be 1.5kg or 6kg depending of motors and H Bridge power. Due to wheels size this robots will be more appropriate to be used on a flat floor such as a robotic competition floor or sport hall.

I bought the first board on Sparkfun : IOIO 10585. But since, a new version was release : IOIO 10748. This board has been develop by ytai as an open source project. It is a very active project and many information could be find here : ytai blog or here : IOIO google group

general view of IOIO board

Few weeks ago, I choose to develop a differential drive robot with my friends Sylvère (software), P’tit Flo (hardware design) and PA. We all want to design a very high level 2 wheels robot.

This is a view of the very early stage robot (hugh… I mean the electronic stuff, not the baby…):

Scalpel 1.5 Robot : My daughter at work

Here is the first print screen of my android app to control the robot :

First print screen of the scalpel android app.

The displayed map is the obstacle presence probability. This map is loaded from a bitmap and distance sensors (sharp gp2d120) are used to display real obstacles on the map. This map will be used as input of some path finding algorithm implementations.

It runs on my nexus S android phone. It runs well without lags or cpu overloading. My first tests told me that the basic control loops takes less than 5% of the cpu. Still, I have the secret hope to make some onboard video processing using the built camera.

Scapel1,5kg proto - Motor wheel and odometric wheel

Scapel1,5kg proto - Side view

Many parts has been done using 3D printing :

Scapel proto : 3D Printing parts

Tires was melt in silicon :

Scalpel proto : tire's silicon mould and wheel frame

Magnetic encoder frame et silicon tires

Here is the general view of electronic design :

Scalpel 1.5 proto : general electronic description

I did a video, it is not well done and the music is border line sorry

http://www.youtube.com/watch?v=kSdCF8Fturk

Florent (voice)
Alexis (Vielle à roue)
Mathieu (bass)
Me (drums)

Five years of development in embedded software for humanoid robots shared with fellow researchers and developers.

(May 13, 2011 – ICRA Shanghai, China) Aldebaran Robotics, the world-leading European humanoid robotics company announced at the 2011 IEEE International Conference on Robotics and Automation its decision to share a significant part of its source code with the research and developer community by the end of 2011.

“We will release our software as OPEN SOURCE to allow researchers, teachers, and developers to adapt and extend our software according to their needs and knowledge, said Bruno Maisonnier, the founder and CEO of Aldebaran Robotics. “Building robotics applications is challenging: applications are built upon many state-of-the-art complex technologies like speech recognition, object recognition, grasping, navigation and mapping. Applications need to be secure and be able to run in a constrained environment with limited resources. With over five years of experience in developing embedded systems for robotics platforms, we want to share our middleware, our core communication library, our cross-platform build tools and other essential modules with researchers, developers and emerging projects in humanoid robotics”, he added.

NAOqi, the embedded software on NAO, includes a highly cross-platform, fast, secure, reliable and distributed robotics framework which provides a comprehensive foundation for developers to leverage and improve NAO’s functionality.

Check the full announcement on the NAO Developer Program website

Either way, you’re bound to love these great videos by Taylor Veltrop! Taylor, one of the very first members of the NAO Developer Program, has created a robot teleoperation system using the Kinect and Wii-motes which won 3rd place in the ROS 3D Kinect contest!

For more information about the NAO Developer Program, go to http://www.aldebaran-robotics.com/developer_program.

http://www.youtube.com/watch?v=bfKgPejez9I

http://www.youtube.com/watch?v=4R7BNms88y4

As you know, you must be invited by a community member to have a chance to be selected.

Linux, Python, or C++ don’t have any secrets for you and you think you can do amazing things that could give Nao even more skills and fun ?

Here is your chance to be one of these 200 pioneer developers!

We reserved a couple of invitations especially for this occasion and will distribute them to you.

Just send us an email to developer at aldebaran-robotics.com about your motivations and skills or post a comment below.