Holding arrangement having an apparatus for balancing a load torque

A holding arrangement for an instrument including a medical-optical instrument, the holding arrangement comprising:

• at least one rotational joint which is subjected to a load torque by said instrument;
• and,
• an apparatus for balancing said load torque applied to said rotational joint;
• said apparatus including:
• an electric motor;
• a detecting unit for detecting a position of said rotational joint and for providing a signal representing a position value for said position of said rotational joint;
• and, said electric motor being combined with said detecting unit;
• a control unit for receiving said signal and assigning a motor current to said position value;
• said control unit outputting said motor current to said electric motor so as to cause said electric motor to generate a counter torque to balance said load torque applied to said rotational joint;
• said apparatus further comprising a brake assigned to said rotational joint;
• said apparatus further comprising a gear assembly for coupling said electric motor to said rotational joint;
• said rotational joint defining a rotational axis and said electric motor defining a drive axis offset relative to said rotational axis;
• said detecting unit including an encoder of said electric motor or a position transducer;
• and,
• an electronic memory assigned to said control unit;
• and, said electronic memory having a curve of current as a function of rotational joint position or a table of current/rotational joint stored therein.

A holding arrangement for an instrument including a medical-optical instrument, the holding arrangement comprising:

• at least one rotational joint which is subjected to a load torque by said instrument;
• and,
• an apparatus for balancing said load torque applied to said rotational joint,
• said apparatus including:
• an electric motor;
• a detecting unit for detecting a position of said rotational joint and for providing a signal representing a position value for said position of said rotational joint;
• and, said electric motor being combined with said detecting unit;
• a control unit for receiving said signal and assigning a motor current to said position value;
• and,
• said control unit outputting said motor current to said electric motor so as to cause said electric motor to generate a counter torque to balance said load torque applied to said rotational joint;
• said rotational joint being a first rotational joint and said apparatus being a first apparatus and wherein said holding arrangement further comprises a second rotational joint and a second apparatus for balancing a second load torque caused by said instrument and applied to said second rotational joint;
• said electric motor of said first apparatus being a first electric motor and said second apparatus including a second electric motor;
• said control unit including two control loops;
• and,
• each of said apparatus further comprising means for detecting a time-dependent change of the position of the rotational joint corresponding thereto and for supplying said time-dependent change to said control loops;
• and, said control loops outputting two motor currents for corresponding ones of said electric motors which counter the change of position of said rotational joints.

A method for determining a current control curve for adjusting an equilibrium state in a holding arrangement which includes:

• at least one rotational joint which is subjected to a load torque by said instrument;
• and, an apparatus for balancing said load torque applied to said rotational joint;
• said apparatus including:
• an electric motor;
• a detecting unit for detecting a position of said rotational joint and for providing a signal representing a position value for said position of said rotational joint;
• and, said electric motor being combined with said detecting unit;
• a control unit for receiving said signal and assigning a motor current to said position value;
• said control unit outputting said motor current to said electric motor so as to cause said electric motor to generate a counter torque to balance said load torque applied to said rotational joint;
• the method comprising the steps of:
• rotating said rotational joint about said rotational axis thereof utilizing said electric motor;
• determining the current demand of said electric motor required to effect the movement of said rotational joint about said rotational axis;
• determining the instantaneous position of said rotational joint;
• and,
• storing said current demand as a current control curve in an electronic memory as a function of the position of said rotational joint.

A method for adjusting an equilibrium state in a holding arrangement which includes:

• at least one rotational joint which is subjected to a load torque by said instrument;
• and, an apparatus for balancing said load torque applied to said rotational joint;
• said apparatus including:
• an electric motor;
• a detecting unit for detecting a position of said rotational joint and for providing a signal representing a position value for said position of said rotational joint;
• and, said electric motor being combined with said detecting unit;
• a control unit for receiving said signal and assigning a motor current to said position value;
• said control unit outputting said motor current to said electric motor so as to cause said electric motor to generate a counter torque to balance said load torque applied to said rotational joint;
• the method comprising the steps of:
• determining an instantaneous position of said rotational joint;
• and,
• supplying current to said electric motor in correspondence to a current control curve stored in a memory with said current control curve assigning a current value for torque compensation to said instantaneous position of said rotational joint.

A method for determining a current control curve for adjusting a state of equilibrium in a holding arrangement which includes:

• at least one rotational joint which is subjected to a load torque by said instrument;
• and, an apparatus for balancing said load torque applied to said rotational joint;
• said apparatus including:
• an electric motor;
• a detecting unit for detecting a position of said rotational joint and for providing a signal representing a position value for said position of said rotational joint;
• and, said electric motor being combined with said detecting unit;
• a control unit f or receiving said signal and assigning a motor current to said position value;
• said control unit outputting said motor current to said electric motor so as to cause said electric motor to generate a counter torque to balance said load torque applied to said rotational joint;
• said rotational joint being a first rotational joint and said apparatus being a first apparatus;
• a second rotational joint and a second apparatus for balancing a second load torque caused by said instrument and applied to said second rotational joint;
• said electric motor of said first apparatus being a first electric motor and said second apparatus including a second electric motor;
• the method comprising the steps of:
• detecting the position of said first rotational joint;
• with the position of said first rotational joint known, moving said second rotational joint about its axis utilizing said second electric motor;
• determining the current demand of said second electric motor needed to move said second rotational joint;
• determining the instantaneous position of said second rotational joint;
• storing the current demand in dependence upon the position of said second rotational joint as a first current control curve in an electronic memory;
• thereafter, and for the known position of said second rotational joint, moving said first rotational joint about its axis utilizing said first electric motor;
• determining the current demand of said first electric motor needed for the movement of said first rotational joint;
• determining the instantaneous position of said first rotational joint;
• and,
• storing the determined current demand in dependence upon the position of said first rotational joint in said electronic memory as a second current control curve.

A method for adjusting a state of equilibrium in a holding arrangement which includes:

• at least one rotational joint which is subjected to a load torque by said instrument;
• and, an apparatus for balancing said load torque applied to said rotational joint;
• said apparatus including:
• an electric motor;
• a detecting unit for detecting a position of said rotational joint and for providing a signal representing a position value for said position of said rotational joint;
• and, said electric motor being combined with said detecting unit;
• a control unit for receiving said signal and assigning a motor current to said position value;
• said control unit outputting said motor current to said electric motor so as to cause said electric motor to generate a counter torque to balance said load torque applied to said rotational joint;
• said rotational joint being a first rotational joint and said apparatus being a first apparatus;
• a second rotational joint and a second apparatus for balancing a second load torque caused by said instrument and applied to said second rotational joint;
• said electric motor of said first apparatus being a first electric motor and said second apparatus including a second electric motor;
• the method comprising the steps of:
• determining an instantaneous position of said first rotational joint;
• determining an instantaneous position of said second rotational joint;
• supplying current to said first electric motor and said second electric motor in correspondence to a current control curve stored in a memory;
• and,
• wherein said current control curve assigns each of said first and second electric motors a current value for torque compensation in correspondence to the respective ones of said instantaneous positions.