Motor control device and motor control method, control system and location estimation method used in control system

A motor control method for controlling a motor that operates a robot,

• wherein a position deviation is calculated based on the position command for controlling said motor and the actual rotational position of said motor, said position deviation is converted to a speed command, the speed deviation is calculated based on said speed command and said actual rotational speed of said motor, and said speed deviation is converted to a torque command;
• when the value of said torque command is below a predetermined limit level, said motor is driven based on said torque command as is;
• when the value of said torque command exceeds said limit level, said motor is driven based on said torque command having said limit level as its value;
• and
• wherein, in response to a voltage of a power source of said motor dropping below a predetermined reference level, the rotation speed of said motor is reduced and said speed command is limited.

A motor control device for use with a power source and a motor including an encoder, the motor control device comprising:

• a voltage fluctuation unit configured to detect a voltage drop in which a voltage output by power source falls below a predetermined reference value;
• a position command unit configured to output a position command and, in response to the voltage fluctuation unit detecting the voltage drop, vary the positional command to reduce a rotational speed of the motor;
• a position detection unit configured to receive an output of the encoder and calculate a rotational position of the motor based on the output of the encoder;
• a first subtraction unit configured to receive the rotational position of the motor from the position detection unit and receive a positional command from the position command unit, the first subtraction unit being further configured to calculate a position deviation by subtracting the rotational position from the position command;
• a position control unit configured to receive the position deviation from the first subtraction unit and output a target rotational speed based on the position deviation, the position control unit being further configured to, in response to the voltage fluctuation unit detecting the voltage drop, limit the target rotational speed that is output;
• a speed detection unit configured to calculate a rotational speed of the motor based on the output of the encoder;
• a second subtraction unit configured to receive the rotational speed of the motor from the speed detection unit and the target rotational speed from the position control unit, the second subtraction unit being further configured to calculate a speed deviation by subtracting the rotational speed of the motor from the target rotational speed;
• a speed control unit configured to receive the speed deviation from the second subtraction unit and convert the speed deviation into a torque command;
• a limiter configured to receive the torque command control unit, compare the torque command to a predetermined torque limit, output the torque command if the torque command is below the predetermined torque limit, and output the predetermined torque limit if the torque command is equal to or greater than the predetermined torque limit;
• and
• a motor driver configured to receive the output of the limiter and apply a voltage from the power source to the motor based on output of the limiter.