Compliation and build

You also need the following ros packages

$ sudo apt-get install ros-indigo-ridgeback-*
$ sudo apt-get install ros-indigo-universal-robot

if you are getting error for broken packages (most probably due to a wrong version of gazebo), you can use 'aptitude' instead of 'apt-get' which propose a solution and resolve the conflict.

Finally complie

$ cd ~/catkin_ws
$ catkin_make
$ source devel/setup.bash
$ catkin_make

you might need the source the bash file and compie again if the first compliation could not find some of in house dependencies.

For simulator, you can use gazebo7

$ sudo apt-get install ros-indigo-gazebo7-*

You might need to follow these instructions.

Control Architecture

Kinematics and transformations

Here is a short list of important frames and their usage.

frame id	Usage
world	Odometry and navigation
ur5_arm_base_link	Arm pose and twist
base_link	Platform pose and twist
robotiq_force_torque_frame_id	External force applied to the end-effector

Adamittance dynamics

The following figure shows the controller architecture for the admittance control on the robot.

The two equations in the center describe the admittance dynamics which compute the desired accelaration for the arm and the platform. These accelerations are integrated in time to acheive the desired velocities for the robot. The low-level velocity controller fullfills these velocities. In the case of platform, the computed velocities can be modified accroding to obstacle avoidance node.

The admittance parameters (shown in purple) are as follows:

Variable	Parameter
M_a	Desired mass of the arm
D_a	Desired damping of the arm
D_c	Desired damping of the coupling
K_c	Desired Stiffness of the coupling
M_p	Desired mass of the platform
D_p	Desired damping of the platform

These parameters are load from a yaml through the launch file.

External force

The external is initially measured by the force/torque sensor in its own frame reference. In admittance controller this force is transformed to "ur5_arm_base_link" where the control of arm takes place. To avoid reacting to small forces a deadzone is considered. Moreover, a low-pass filter is used to smooth the measurements. The parameters of the deadzone and the filter can be set from the launch file.

Higher-level control (Motion planning )

Through a higher level controller, the position of the equilibrium can be can be changed to acheive a desired behavior. Also, F_c can be used for control purposes; e.g., to compensate for the mass of an object carried by the arm.

这里面的用的controller其实和UR之前下载的controller没有什么本质的区别,仅仅是控制模式不一样而已,一个是velocity,而另一个是joint_trajectory,以后需要用到cartesian space的速度可以考虑用这个包!

仿真程序

roslaunch ur5_admittance_control admittance_controller.launch

真实程序

roslaunch ur5_admittance_control admittance_controller.launch sim:=false F/T_sensor:=true

安装错误

因为这个包很多ur的东西,所以很容易产生错误，如果错误无法解决，controller之类的错误，就把catkin_ws环境下的其他包移除，只留force_control的几个包然后，catkin_make就可以了

qwq321qwq/force_control