Emmanuel Posted April 24, 2018 Share Posted April 24, 2018 Having spent a considerable amount of time striving to discover a topic related to the external wrenches/contact forces, all my efforts have been to no avail. Is there any means of acquiring end-effector contact force feedback (3 moments and 3 forces) through the Intera SDK? How do the existing interaction/force control algorithms function without this feedback? Quote Link to comment Share on other sites More sharing options...
Ian McMahon Posted April 24, 2018 Share Posted April 24, 2018 Hi Emmanuel, You can find the forces acting upon the end effector on the following topic: /robot/limb/right/endpoint_state The messages on this topic consist of intera_core_msgs/EndpointState . They contain Wrenches and Torques for the endpoint: std_msgs/Header header ... geometry_msgs/Pose pose ... geometry_msgs/Twist twist ... geometry_msgs/Wrench wrench geometry_msgs/Vector3 force float64 x float64 y float64 z geometry_msgs/Vector3 torque float64 x float64 y float64 z bool valid You can expect to see the force of gravity in the force value, but aside from that this message will show you the external forces you're looking for. Please let us know if you have any additional questions. Best, ~ Ian 1 1 Quote Link to comment Share on other sites More sharing options...
Emmanuel Posted April 30, 2018 Author Share Posted April 30, 2018 Hi Ian, Thank you for the enlightening response, and apologies for the belated acknowledgement. I will be more attentive next time. Best regards, Emmanuel Quote Link to comment Share on other sites More sharing options...
Emmanuel Posted May 11, 2018 Author Share Posted May 11, 2018 Hi Ian, It has recently come to my attention that the following topic: /robot/limb/right/endpoint_state does not actually provide the external wrench values 'felt' by the end-effector, which would have been provided if a force/torque sensor were incorporated into the tip of the end-effector. It appears as though the forenamed topic actually publishes external force/moment values generated using some kind of disturbance observer. Otherwise, I would be led to assume that the mere motion of the system is inducing noisy signals into the wrench readings. Is there any means of acquiring the actual wrenches at the end-effector, which would imply the generation of solely zero values during 'free motion', and non-zero values during environmental contact at the end-effector? Kind regards, Emmanuel Quote Link to comment Share on other sites More sharing options...
Danfei Posted May 19, 2018 Share Posted May 19, 2018 Kind of related to this: What is in the field "endpoint_force_command" of the messages in the topic: /robot/limb/right/interaction_controller/state ? I expected to see directly my commands when I send a desired force to the interaction_controller, but that is not the case. Are they computed from \tau of the joints? Do you subtract gravity? Thanks --Roberto Quote Link to comment Share on other sites More sharing options...
Yufei Posted March 20 Share Posted March 20 On 4/24/2018 at 11:04 AM, Ian McMahon said: Hi Emmanuel, You can find the forces acting upon the end effector on the following topic: /robot/limb/right/endpoint_state The messages on this topic consist of intera_core_msgs/EndpointState . They contain Wrenches and Torques for the endpoint: std_msgs/Header header ... geometry_msgs/Pose pose ... geometry_msgs/Twist twist ... geometry_msgs/Wrench wrench geometry_msgs/Vector3 force float64 x float64 y float64 z geometry_msgs/Vector3 torque float64 x float64 y float64 z bool valid You can expect to see the force of gravity in the force value, but aside from that this message will show you the external forces you're looking for. Please let us know if you have any additional questions. Best, ~ Ian Hi, thanks for pointing to this topic. I am wondering if there is a more detailed documentation on how is the force and torque computed? Are they measuring the same thing as say, if we mount a force-torque sensor to the robot end-effector? Quote Link to comment Share on other sites More sharing options...
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