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Hello, I have been simulating a turtlebot3 waffle pi in Gazebo, and been using velocities as high as 0.5m/s. Looking at the hardware specifications: https://emanual.robotis.com/docs/en/p..., it says that the max velocity is 0.26 m/s. Does this mean that it can drive at 0.5m/s in the simulations, but not physically because of hardware limitations?
As keenly observed by @Roshan, the Turtlebot3 simulation linear velocity can be set higher than the physical robot.
The main function:
void Turtlebot3Fake::commandVelocityCallback(const geometry_msgs::TwistConstPtr cmd_vel_msg)
{
last_cmd_vel_time_ = ros::Time::now();
goal_linear_velocity_ = cmd_vel_msg->linear.x;
goal_angular_velocity_ = cmd_vel_msg->angular.z;
wheel_speed_cmd_[LEFT] = goal_linear_velocity_ - (goal_angular_velocity_ * wheel_seperation_ / 2);
wheel_speed_cmd_[RIGHT] = goal_linear_velocity_ + (goal_angular_velocity_ * wheel_seperation_ / 2);
}
https://github.com/ROBOTIS-GIT/turtle...
Doesn't check for:
#define MAX_LINEAR_VELOCITY 0.22 // m/s
#define MAX_ANGULAR_VELOCITY 2.84 // rad/s
found at: https://github.com/ROBOTIS-GIT/turtle...
To simulate accurately, it's suggested to just a check for maximum velocity like in the teleop program:
def checkLinearLimitVelocity(vel):
if turtlebot3_model == "burger":
vel = constrain(vel, -BURGER_MAX_LIN_VEL, BURGER_MAX_LIN_VEL)
elif turtlebot3_model == "waffle" or turtlebot3_model == "waffle_pi":
vel = constrain(vel, -WAFFLE_MAX_LIN_VEL, WAFFLE_MAX_LIN_VEL)
else:
vel = constrain(vel, -BURGER_MAX_LIN_VEL, BURGER_MAX_LIN_VEL)
return vel
Asked: 2021-12-26 04:14:42 -0500
Seen: 1,176 times
Last updated: Dec 27 '21
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Hi @Roshan
If the simulation is higher than specs it must be that a configuration file has been changed. I checked from the repo and the simulation matches robot spec:
BURGER_MAX_LIN_VEL = 0.22 BURGER_MAX_ANG_VEL = 2.84
WAFFLE_MAX_LIN_VEL = 0.26 WAFFLE_MAX_ANG_VEL = 1.82
LIN_VEL_STEP_SIZE = 0.01 ANG_VEL_STEP_SIZE = 0.1
https://github.com/ROBOTIS-GIT/turtle...
That's weird, I haven't changed the configuration file, but I can still publish for example 0.5 or 1 into the cmd_vel and see changes. Does the 0.5 I'm publishing into the cmd_vel mean something other than velocity maybe?
And here as well: https://github.com/ROBOTIS-GIT/turtle...
You can publish any speed but the robot will just go to your max speed
I think you may be right:
https://github.com/ROBOTIS-GIT/turtle...
It never checks against max velocity just checks against published velocity
Ah ok, so that does mean that the simulations don't actually have a max velocity, but once you start using a physical setup the max velocity will be at 0.26 m/s for linear velocity
That’s correct. You could add the checks like in the teleop program
Hi @Roshan, Added an answer to complete the cycle and summarize our discussion.