A surgical device includes an end effector having a pair of opposing jaw members and a drive beam movable longitudinally through the pair of opposing jaw members thereby approximating the pair of opposing jaw members relative to each other. The device also includes an adapter assembly configured to selectively couple to the end effector. The adapter assembly includes an actuation assembly configured to mechanically engage the drive beam and to move the drive beam longitudinally. The device also includes a handle assembly configured to selectively couple to the adapter assembly. The handle assembly includes: a power source, a motor coupled to the power source, a sensor configured to measure a force imparted on the drive beam, and a motor controller configured to control the motor to maintain constant force on the drive beam based on the force measured by the sensor during longitudinal movement of the drive beam approximating the pair of opposing jaw members closer relative to each other.