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JointTrajectory: Don't use shortest_angular_distance for linear joints #623

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JointTrajectory: Don't use shortest_angular_distance for linear joints #623

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1 change: 1 addition & 0 deletions ...t_trajectory_controller/include/joint_trajectory_controller/joint_trajectory_controller.h
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Original file line number Diff line number Diff line change
Expand Up @@ -182,6 +182,7 @@ class JointTrajectoryController : public controller_interface::Controller<Hardwa
std::string name_; ///< Controller name.
std::vector<JointHandle> joints_; ///< Handles to controlled joints.
std::vector<bool> angle_wraparound_; ///< Whether controlled joints wrap around or not.
std::vector<bool> is_linear_; ///< Whether controlled joints are linear or not.
std::vector<std::string> joint_names_; ///< Controlled joint names.
SegmentTolerances<Scalar> default_tolerances_; ///< Default trajectory segment tolerances.
HwIfaceAdapter hw_iface_adapter_; ///< Adapts desired trajectory state to HW interface.
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17 changes: 16 additions & 1 deletion ...jectory_controller/include/joint_trajectory_controller/joint_trajectory_controller_impl.h
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Expand Up @@ -254,6 +254,7 @@ bool JointTrajectoryController<SegmentImpl, HardwareInterface>::init(HardwareInt
// Initialize members
joints_.resize(n_joints);
angle_wraparound_.resize(n_joints);
is_linear_.resize(n_joints);
for (unsigned int i = 0; i < n_joints; ++i)
{
// Joint handle
Expand All @@ -267,13 +268,16 @@ bool JointTrajectoryController<SegmentImpl, HardwareInterface>::init(HardwareInt

// Whether a joint is continuous (ie. has angle wraparound)
angle_wraparound_[i] = urdf_joints[i]->type == urdf::Joint::CONTINUOUS;
is_linear_[i] = urdf_joints[i]->type == urdf::Joint::PRISMATIC;
const std::string not_if = angle_wraparound_[i] ? "" : "non-";
const std::string linear = is_linear_[i] ? "linear " : "";

ROS_DEBUG_STREAM_NAMED(name_, "Found " << not_if << "continuous joint '" << joint_names_[i] << "' in '" <<
ROS_DEBUG_STREAM_NAMED(name_, "Found " << not_if << "continuous " << linear << "joint '" << joint_names_[i] << "' in '" <<
this->getHardwareInterfaceType() << "'.");
}

assert(joints_.size() == angle_wraparound_.size());
assert(joints_.size() == is_linear_.size());
ROS_DEBUG_STREAM_NAMED(name_, "Initialized controller '" << name_ << "' with:" <<
"\n- Number of joints: " << getNumberOfJoints() <<
"\n- Hardware interface type: '" << this->getHardwareInterfaceType() << "'" <<
Expand Down Expand Up @@ -779,6 +783,17 @@ updateStates(const ros::Time& sample_time, const Trajectory* const traj)
desired_state_.velocity[joint_index] = desired_joint_state_.velocity[0];
desired_state_.acceleration[joint_index] = desired_joint_state_.acceleration[0];

if (is_linear_[joint_index])
{
state_joint_error_.position[0] = desired_joint_state_.position[0] - current_state_.position[joint_index];
}
else
{
state_joint_error_.position[0] = angles::shortest_angular_distance(current_state_.position[joint_index],desired_joint_state_.position[0]);
}
state_joint_error_.velocity[0] = desired_joint_state_.velocity[0] - current_state_.velocity[joint_index];
state_joint_error_.acceleration[0] = 0.0;

state_error_.position[joint_index] = angles::shortest_angular_distance(current_state_.position[joint_index],desired_joint_state_.position[0]);
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Suggested change
if (is_linear_[joint_index])
{
state_joint_error_.position[0] = desired_joint_state_.position[0] - current_state_.position[joint_index];
}
else
{
state_joint_error_.position[0] = angles::shortest_angular_distance(current_state_.position[joint_index],desired_joint_state_.position[0]);
}
state_joint_error_.velocity[0] = desired_joint_state_.velocity[0] - current_state_.velocity[joint_index];
state_joint_error_.acceleration[0] = 0.0;
state_error_.position[joint_index] = angles::shortest_angular_distance(current_state_.position[joint_index],desired_joint_state_.position[0]);
if (is_linear_[joint_index])
{
state_error_.position[joint_index] = desired_joint_state_.position[0] - current_state_.position[joint_index];
}
else
{
state_error_.position[joint_index] = angles::shortest_angular_distance(current_state_.position[joint_index],desired_joint_state_.position[0]);
}

state_error_.velocity[joint_index] = desired_joint_state_.velocity[0] - current_state_.velocity[joint_index];
state_error_.acceleration[joint_index] = 0.0;
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