Tethered payload motion control and cable robot using magnetorheological actuators

A system for controlling a tension of a tensioning member between an object and a load tethered to the object comprising

• at least two tensioning sets, each said tensioning set having
• at least one magnetorheological (MR) fluid actuator unit including at least one torque source and at least one MR fluid clutch apparatus coupled to the at least one torque source to receive torque from the at least one torque source, the MR fluid clutch apparatus containing a MR fluid and having an electromagnet being controllable to vary an apparent viscosity of the MR fluid to transmit a variable amount of torque via an output of the MR fluid actuator unit, and
• a tensioning member being connected to the output so as to be pulled by the output upon actuation of the magnetorheological fluid clutch apparatus, a free end of the tensioning member adapted to exert a pulling action when being pulled by the output;
• at least one sensor for providing information indicative of a relation between the object and the load tethered to the object;
• and
• a controller for controlling the MR fluid clutch apparatuses in exerting the pulling action based on said information, the controller configured for adjusting a strength of a magnetic field generated by the electromagnet based on said information, the controller for controlling the MR fluid clutch apparatuses for a first of the tensioning sets to provide a force on the output antagonistic to a transmission of the pulling action of a second of the tensioning sets on the output.

A method for controlling a force between at least two aircrafts and a load tethered to the at least two aircrafts, comprising

• a processing unit;
• and
• a non-transitory computer-readable memory communicatively coupled to the processing unit and comprising computer-readable program instructions executable by the processing unit for:
• obtaining information indicative of a relation between the at least two aircrafts and the load tethered to the at least two aircrafts;
• characterizing the relation from the information;
• determining from the characterizing a level of action required to control the relation;
• and
• controlling at least one MR fluid clutch apparatus to transmit a variable amount of torque via an output of the at least one MR fluid clutch apparatus to control a tension on at least one tensioning member between the load and the at least two aircrafts, including adjusting a strength of a magnetic field to vary an apparent viscosity of a MR fluid to control the force based on the level of action.