Mobile Robot Base for Reachy

Hi Everyone,

Has anyone tried mounting the Reachy robot onto a mobile robot, for instance a robot from YouBot or another company, so you could control Reachy to move across an environment?

If so, what have been your experiences around this?

One of my concerns could be the center of mass of the robot while the arms are being moved around and the possibility of it to tip over because of any swaying motion caused by the arms and/or by the acceleration and deceleration of the mobile base.

Thank you,

Hi Ivan!

We haven’t mounted Reachy on an existing robot yet, but we are working on a prototype of our own mobile base .

Indeed, the robot could fall forward when we suddently stopped while the arms were extended in front of him.
The solution was to put the center of mass a bit more in the back of the mobile base, the wheels in the front, and we put a kind of stopper part in the front of the platform so that it touches the ground before the robot falls.

This is not the final solution, just a prototype to make reachy do his first moves :wink: We are already working on better solutions.

If you have any thought about it, ideas or solutions to share, feel free to do it here, that would help us! :smiley:


Hi Augustin,

Great to know you are also working on this.

I think the problem with the center of mass could also be worse depending on the number of arms, for instance of the robot only has one arm, you would need to also balance out weight of it.

One thing I thought of is to change the placement of the arms closer to the center of the body during different speeds (the faster the robot moves the closer the arms are to the robot’s center of mass) or during deceleration.

I also had the idea of putting the center of mass in the back, you just have to be careful when moving the robot backward and then suddenly stopping, but the stopper part you mentioned is a good solution for prototyping to keep the robot from being damaged.

Have you guys tried using the Unity plugin to try to simulate placing Reachy on a mobile base to test multiple base configurations, speeds, and different terrain types/inclinations, objects held while navigating, etc. before creating a physical prototype of the mobile base? I’m thinking of doing this but I’m not sure how much fidelity in the virtual environment and test results I can expect from it to transfer over to the real world.

Unity’s new robotics hub looks like a possible solution, they also have an example of mobile robot control using ROS.


Hi Ivan, Augustin,

Just in case it can help: the ETIS laboratory (Cergy, 95) asked for the same needs, so we have co-developped with my company (Instar Robotics) a mobile platform suited for the Reachy (see attached image). The platform weight around 65 kg, so there is no chance for the robot to tip over. However the platform is an heavy-duty one (75x70x40cm), designed for rough outdoor terrain, and it might not be the best fit for small indoors. I don’t know what exactly is your use-case for the reachy.
Anyway, the platform is available, if ever.


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Hi @Adrien ,

That’s great to hear you have already come up with a solution for this, and for use outside which can be more difficult with uneven terrains.

In my case I am looking into a platform for indoor use through narrow corridors and to avoid bumping into walls, chairs, people, etc. or at least if bumping does occur, it won’t damage the robot or hurt others. I’m considering about using some proximity sensors to help with this.

One thing I was thinking about is the rotation of the robot, if it would be helpful to rotate just the upper body (Reachy) or rotate the lower body (the mobile base) when performing in-place rotations in some cases.


Hi @A-Ivan ,

Our mobile platform is already equipped with a Lidar that can perceive obstacle up to 60m with a 0.25 degree angular precision. The placement of the lidar allows to see obstacles at 180° front, but not 360°. An obstacle memory map is mandatory to avoid bumping into obstacles when moving backward for exemple. But without memory map, it is ok to avoid obstacle while moving forward.

The size of the mobile base allows to pass through doors or corridors down to 80cm large, but you have to carefully drive it forward in this case. If you want a full 360° rotation of the mobile base, you will need a free space of at least 1.2m diameter, otherwise the back of the robot will bump into nearby obstacles.

About the rotation of the platform: The mobile base itself can rotate in-place.
But the Reachy is also mounted on a motorized axis (360° rotation). It means you can actually rotate the upper part (Reachy) without rotating the lower body (mobile base) if needed.