Rotation controller for a differential actuator

A rotation control apparatus used for a differential actuator having two induction motors and a differential mechanism for producing on an output shaft a constant torque at varying rotational speeds of said induction motors, said apparatus comprising two inverters each connected between a corresponding one of said induction motors and a power source which supplies power to said induction motors and adapted to set frequencies of power supplied to said induction motors so as to control the rotational speed of said output shaft based on the difference of frequencies of power supplied to said induction motors;

• wherein one of said two inverters provides a constant-frequency power to one of said induction motors and the other inverter for provides a variable-frequency power to the other of said induction motors;
• said apparatus controlling said differential actuator to produce a constant torque on the output shaft thereof at a differential speed between said induction motors at each variable frequency;
• and
• a digital torque sensor attached to said output shaft of said differential actuator for meauring the output torque on said output shaft in a digital manner, said digital torque sensor having a measured value read out on a torque meter, torque control being implemented by setting a frequency of said variable-frequency inverter.

A differential actuator for producing a differential output from two induction motors and outputting a high torque driving force at low speed, each of said induction motors being connected to a power source by a corresponding one of two inverters, comprising:

• (a) two axially-aligned induction motors arranged to be driven at selected rotational speeds;
• (b) two aligned hollow input shafts, each of said induction motors being connected to a corresponding one of said hollow input shafts for driving said shafts;
• (c) output shafts aligned with said induction motors and extending through said hollow input shafts and rotatable relative to said hollow input shafts;
• and
• (d) differential means connecting said hollow input shafts and said output shafts.

A differential actuator for providing a differential output from two motors and outputting a high torque driving force at low speed, each of said motors being controlled by a corresponding one of two inverters, comprising:

• (a) a case;
• (b) two motors arranged within said case at opposite ends thereof and to be driven at selected rotational speeds;
• (c) two hollow input shafts, each of said motors being connected to a corresponding one of said hollow input shafts for driving said shafts;
• (d) two oppositely facing side bevel gears arranged on a first axis, each of said bevel gears being attached to a corresponding one of said hollow input shafts, said hollow input shafts being rotatable at different speeds by said motors;
• (e) two oppositely facing pinion bevel gears engaging said two side bevel gears, said pinion bevel gears being arranged on a second axis which is perpendicular to said first axis;
• (f) a differential shaft extending between said pinion bevel gears along said second axis;
• (g) output shafts extending through said hollow input shafts and through opposite ends of said case and being rotatable relative to said hollow input shafts, said output shafts being connected at their inner ends to said differential shaft.