In described examples, a device includes a processor and a non-transitory memory storing instructions that, when executed, cause the processor to operate in an open loop mode a motor that includes a rotor and a stator. An angle error of the rotor is determined. In response to the angle error of the rotor being less than a threshold, the processor transitions from operating the motor in the open loop mode to operating the motor in a closed loop mode by changing from using a first coordinate system based on a command rotor position to using a second coordinate system based on an estimated rotor position to determine current vectors used to control the motor; and holding constant a current vector used to control the motor while performing the changing action. After performing the changing and holding actions, the processor operates the motor in the closed loop mode.

A controller for operating a brushless motor comprising a stator and a rotor is configured to: operate a sliding-mode observer (SMO) process detect an angular position of the rotor; predict an occurrence of a stall condition based on at least one of a rotational speed of the rotor or the phase current of the motor; operate a high-frequency injection (HFI) process in response to predicting the occurrence of the stall condition to determine the angular position of the rotor; determine whether the stall condition has occurred; and transition from the SMO process to the HFI process in response to the determination of the stall condition has occurred. In an embodiment, a power tool is provided including a motor and a controller as described above.

A dual-axis simultaneous motion system is disclosed and includes a first-axis sliding module, a second-axis sliding module, a transverse beam, a bearing, an encoder and a control unit. A first driver of the first-axis sliding module drives a first sliding block to slide. A second driver of the second-axis sliding module drives a second sliding block to slide. The transverse beam is connected to the first sliding block and the second sliding block. The bearing is pivotally connected between the transverse beam and the first or second sliding block. The encoder is configured to measure an angle of the transverse beam relative to the first or second sliding block. The control unit is connected to the first driver, the second driver and the encoder, and controls the first and second driver based on the encoder compensation, so that the first and second sliding blocks drive the transverse beam to slide.

An apparatus comprises a housing; a brushless motor including a rotor; a power switch circuit; a switch disposed on the housing; and a controller. The controller executes the steps of: receiving a power-ON signal from the switch; estimating an angular position of the rotor based on at least one electrical signal associated with a back electromotive force of the brushless motor; operating a switching of the power switch circuit to control a commutation of the brushless motor based on the angular position of the rotor upon receiving the power-ON signal from the switch if a rotational speed of the brushless motor associated with the angular position of the rotor is greater than a predetermined speed threshold; and braking the motor if the rotational speed of the brushless motor less than or equal to the predetermined speed threshold.