# Revision history [back]

### using cmd_vel and navigation stack for our robot

Hi! We have our own robot which has two wheels in the back (each one with an independent motor) and one free wheel on the front. It can already accept commands to move a certain distance forwards or backwards or to move at a certain speed. It can also be told to spin at a certain velocity (one wheel goes backwards and the other forwards, differential). For odometry we have the encoders plus visual odometry from a kinect using ccny_rgbd. That is already working.

Now we are looking up the NAVIGATION STACK and trying to see if we can use it: The tutorial states that our robot has to be able to accept messages on topic /cmd_vel of type "twist". These messages contain linear velocities Vx and Vy and angular velocities Vtheta.

In the case of our robot, for example, if it is looking towards the x-axis, it has to spin before it can have a a Vy velocity. Or it would require a calculating the different speeds needed in each wheel to have them both Vx and Vy at the same time. Any suggestions, help?

Also, my robot can't have all three of these velocities at the same time. Is that possible? Or are the messages supposed to contain all zeros but one of the three componentes?

### using cmd_vel and navigation stack for our robot

Hi! We have our own robot which has two wheels in the back (each one with an independent motor) and one free wheel on the front. It can already accept commands to move a certain distance forwards or backwards or to move at a certain speed. It can also be told to spin at a certain velocity (one wheel goes backwards and the other forwards, differential). For odometry we have the encoders plus visual odometry from a kinect using ccny_rgbd. That is already working.

Now we are looking up the NAVIGATION STACK and trying to see if we can use it: The tutorial states that our robot has to be able to accept messages on topic /cmd_vel of type "twist". These messages contain linear velocities Vx and Vy and angular velocities Vtheta.

In the case of our robot, for example, if it is looking towards the x-axis, it has to spin before it can have a a Vy velocity. Or it would require a calculating the different speeds needed in each wheel to have them both Vx and Vy at the same time. Any suggestions, help?

Also, my robot can't have all three of these velocities at the same time. Is that possible? Or are the messages supposed to contain all zeros but one of the three componentes?

### using cmd_vel and navigation stack for our robot

Hi! We have our own robot which has two wheels in the back (each one with an independent motor) and one free wheel on the front. It can already accept commands to move a certain distance forwards or backwards or to move at a certain speed. It can also be told to spin at a certain velocity (one wheel goes backwards and the other forwards, differential). For odometry we have the encoders plus visual odometry from a kinect using ccny_rgbd. That is already working.

Now we are looking up the NAVIGATION STACK and trying to see if we can use it: The tutorial states that our robot has to be able to accept messages on topic /cmd_vel of type "twist". These messages contain linear velocities Vx and Vy and angular velocities Vtheta.

In the case of our robot, for example, if it is looking towards the x-axis, it has to spin before it can have a a Vy velocity. Or it would require a calculating the different speeds needed in each wheel to have them both Vx and Vy at the same time. Any suggestions, help?

Also, my robot can't have all three of these velocities at the same time. Is that possible? Or are the messages coming out of the navigation stack supposed to contain all zeros but one of the three componentes?

### using cmd_vel and navigation stack for our robot

Hi! We have our own robot which has two wheels in the back (each one with an independent motor) and one free wheel on the front. It can already accept commands to move a certain distance forwards or backwards or to move at a certain speed. It can also be told to spin at a certain velocity (one wheel goes backwards and the other forwards, differential). For odometry we have the encoders plus visual odometry from a kinect using ccny_rgbd. That is already working.

Now we are looking up the NAVIGATION STACK and trying to see if we can use it: The tutorial states that our robot has to be able to accept messages on topic /cmd_vel of type "twist". These messages contain linear velocities Vx and Vy and angular velocities Vtheta.

In the case of our robot, for example, if it is looking towards the x-axis, it has to spin before it can have a a Vy velocity. Or it To have them both at the same time would require a calculating the different speeds needed in each wheel to have them both Vx and Vy at the same time. Any suggestions, help?

Also, my robot can't have all three of these velocities at the same time. Is that possible? Or are the messages coming out of the navigation stack supposed to contain all zeros but one of the three componentes?

### using cmd_vel and navigation stack for our robot

Hi! We have our own robot which has two wheels in the back (each one with an independent motor) and one free wheel on the front. It can already accept commands to move a certain distance forwards or backwards or to move at a certain speed. It can also be told to spin at a certain velocity (one wheel goes backwards and the other forwards, differential). For odometry we have the encoders plus visual odometry from a kinect using ccny_rgbd. That is already working.

Now we are looking up the NAVIGATION STACK and trying to see if we can use it: The tutorial states that our robot has to be able to accept messages on topic /cmd_vel of type "twist". These messages contain linear velocities Vx and Vy and angular velocities Vtheta.

In the case of our robot, for example, if it is looking towards the x-axis, it has to spin before it can have a a Vy velocity. To have them both at the same time would require calculating the different speeds needed in each wheel to have them both Vx and Vy at the same time. Any suggestions, help?

Also, my robot can't have How about having all three of these velocities at the same time. Is that possible? Or are the messages coming out of the navigation stack supposed to contain all zeros but one of the three componentes?