HAS-Motion Software Documentation

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at_least_3_tracking_markers_must_be_attached_to_each_segment_and_recorded_during_the_movement_trial._a_standing_trial_identifies_four_static_markers_that_represent_medial_and_lateral_locations_at_the_proximal_end_of_the_segment_and_the_medial_and_lateral_locations_at_the_distal_end_of_the_segment._scsxperptoyzplane.gif_useful_consequences_of_these_rules._consequence_1._segments_to_do_not_have_to_be_part_of_the_human_body_any_object_can_be_tracked_provided_the_rules_are_followed._those_objects_that_are_not_part_of_the_primary_subject_can_only_be_interpreted_as_kinematics_only_segments._at_this_time_the_dynamics_of_the_interactions_cannot_be_quantified_within_visual3d._the_calculation_of_inverse_dynamics_based_on_signals_collected_from_an_instrumented_handle_are_currently_under_development._assistive_devices_such_as_a_cane_can_be_tracked._external_objects_such_as_peg_boards_can_be_incorporated_into_the_animation._segments_can_be_from_different_bodies_allowing_the_creation_of_models_of_multiple_subjects_in_the_scene._a_robot_can_be_tracked_that_is_interacting_with_the_user_e.g._a_phantom_robot_._consequence_2._segments_of_the_body_can_be_defined_with_more_than_one_segment_coordinate_system._visual3d_assumes_that_segments_are_not_twisted_about_their_longitudinal_axis._if_there_is_a_torsion_of_the_bone_such_that_the_proximal_and_distal_joints_are_rotated_relative_to_each_other_it_might_be_useful_to_create_one_coordinate_system_for_defining_the_proximal_joint_angle_and_a_rotated_coordinate_system_for_defining_the_distal_joint_angle._note_that_only_one_of_these_segments_can_be_considered_part_of_the_inverse_dynamics_calculation_the_other_segment_s_must_be_a_kinematics_only_segment._exceptions_to_these_rules_provide_flexibility._exception_1._common_targets_are_allowed._visual3d_allows_the_user_to_define_the_same_tracking_marker_to_adjacent_segments._for_example_a_marker_placed_on_the_lateral_aspect_of_the_knee_may_be_used_to_track_the_thigh_and_the_shank._under_these_conditions_the_visual3d_model_no_longer_has_6_independent_degrees_of_freedom._exception_2._using_a_movement_trial_as_a_static_trial_visual3d_allows_the_user_to_use_the_movement_trial_as_both_a_movement_trial_and_a_standing_trial_selecting_one_frame_for_processing_._the_movement_trial_must_have_the_four_static_markers_required_to_define_a_segment._exception_3._anatomical_measurements_can_be_used_to_create_virtual_static_markers_visual3d_in_model_builder_mode_allows_the_user_to_create_virtual_markers._these_virtual_markers_are_defined_as_offsets_with_respect_to_an_existing_marker._these_offsets_are_commonly_determined_from_anatomical_measurements_on_the_subject._exception_4._a_3d_digitizer_can_be_used_to_create_virtual_static_markers_some_laboratories_use_a_digitizing_wand_to_locate_anatomical_landmarks._these_landmarks_are_typically_collected_in_the_laboratory_coordinate_system_defined_by_the_video_cameras_._the_user_can_specify_the_digitized_values_as_offsets_from_the_lab_segment_in_model_builder_mode._note_that_these_values_can_also_be_entered_into_the_ascii_model_file._exception_5._defining_virtual_tracking_markers._tracking_markers_are_assumed_to_exist_in_all_movement_trials._the_user_can_create_plug-ins_or_import_data_for_which_virtual_tracking_markers_are_calculated._visual3d_uses_this_approach_to_create_tracking_markers_that_represent_the_virtual_joint_centers_for_helen_hayes_marker_sets._note_that_the_helen_hayes_marker_sets_typically_have_two_tracking_markers_per_segment_and_the_proximal_joint_center._because_the_proximal_joint_center_has_been_calculated_using_information_from_the_proximal_segment_the_helen_hayes_marker_set_does_not_have_6_degrees_of_freedom._this_dependence_on_the_proximal_segment_causes_errors_to_propogate_from_segment_to_segment_e.g._errors_in_the_hip_joint_center_cause_errors_in_determining_the_pose_of_the_foot_._marker_placement_visual3d_interprets_all_marker_sets_in_a_similar_fashion._the_marker_configuration_promoted_for_visual3d_consists_of_a_combination_of_arrays_of_markers_placed_on_a_rigid_surface_and_markers_placed_on_anatomical_landmarks._marker_clusters_marker_set_guidelines}}