PR2 Arm Control
From Healthcare Robotics Wiki
Lowlevel Controllers
Controller  Joint Spline Trajectory Controller  JTranspose Controller  JTranspose Task Controller  JInverse Controller  End Effector Cartesian Impedance Control 

Designer  Stuart Glaser  Stuart Glaser  Adam Leeper  Stuart Glaser  MIT 
Control Space  Joint space  Cartesian Space  Cartesian Space  Cartesian Space  Cartesian Space 
Control Type  Joint position, velocity, acceleration control with PID  Controls force at the end effector with PD on the Cartesian error  Same as JTranspose, shaped stiffness matrix in end effector's frame  Position or Velocity Cartesian control with PD control on joint velocities  Forcestiffness hybrid control, JTranspose on some DOF, force control on others 
Relevant Equations 
T = PID(spline(t, trajectory)  q_cur) 
T = J^T * PD(x_err) + Kff * J_null * (q_posture  q) 
Same but: PD(x_err) = R * Kp * R^T * x_err + R * Kd * R^T * x_dot 
T = Kp * (q_proxy  q) + Kd * (q_dot_des  q_dot) q_dot_des = J_pinv * x_dot + J_null * (q_posture  q) 
T = J^T * F F = PD(x_err) or F_des 
Control reference (the goal the controller is trying to achieve)  joint angles  Cartesian pose of rigid transformation from end effector frame  Cartesian pose of rigid transformation from end effector frame  Cartesian pose of rigid transformation from end effector frame  Cartesian frame attached to end effector with origin at wrist 
ROS Interface 





Demonstrated Tasks 



 
Can provide trajectory as sequence of reference points, velocities, and durations, which it then uses to generate way points (rather than only a single reference)  Yes  No  No  No  Template:Maybe 
Change Gains while the controller is running (through topic)  No  Yes  Yes  No  Yes, if using impedance control 
Integral Control  Yes  No  No  No  No 
Monitors Cartesian velocity and softly scales it (saturation)  No  Yes  Yes  No, not implemented yet  No 
Monitors torque at each joint and softly scales the entire torque vector (saturation)  No  Yes  Yes  No  No 
Pros 



 
Cons 


 
Issues/Bugs 


Notes 


