A robotic surgical system comprising: a robotic arm supporting a jaw assembly, the jaw assembly including opposed jaw members defining a jaw angle (α) therebetween; and a user interface including a handle assembly , the handle assembly including: a body portion ; a handle controller ; and a first actuator movable relative to the body portion to change an opening angle (Θ) of the first actuator , the first actuator having a force profile which is a force required to move the first actuator as a function of the opening angle (θ), and the jaw assembly having a jaw angle profile which is the jaw angle (α) as a function of the opening angle (θ), wherein the force profile defines a force curve, and wherein a microcontroller of the handle controller is configured to record the opening angle (Θ) of the first actuator and adjust operating parameters of a motor of the handle controller to effect a change in the force required to actuate the first actuator based on the force curve, a portion of the force curve having a negative slope in which the force increases as the opening angle decreases, characterised in that : the handle controller is disposed within the body portion of the handle assembly ; and a portion of the force curve has a positive to negative slope transition point at a predetermined opening angle of the first actuator , the motor producing a torque to maintain the first actuator at the predetermined opening angle. a robotic arm supporting a jaw assembly, the jaw assembly including opposed jaw members defining a jaw angle (α) therebetween; and a user interface including a handle assembly , the handle assembly including: a body portion ; a handle controller ; and a first actuator movable relative to the body portion to change an opening angle (Θ) of the first actuator , the first actuator having a force profile which is a force required to move the first actuator as a function of the opening angle (θ), and the jaw assembly having a jaw angle profile which is the jaw angle (α) as a function of the opening angle (θ), a body portion ; a handle controller ; and a first actuator movable relative to the body portion to change an opening angle (Θ) of the first actuator , the first actuator having a force profile which is a force required to move the first actuator as a function of the opening angle (θ), and the jaw assembly having a jaw angle profile which is the jaw angle (α) as a function of the opening angle (θ), wherein the force profile defines a force curve, and wherein a microcontroller of the handle controller is configured to record the opening angle (Θ) of the first actuator and adjust operating parameters of a motor of the handle controller to effect a change in the force required to actuate the first actuator based on the force curve, a portion of the force curve having a negative slope in which the force increases as the opening angle decreases, the handle controller is disposed within the body portion of the handle assembly ; and a portion of the force curve has a positive to negative slope transition point at a predetermined opening angle of the first actuator , the motor producing a torque to maintain the first actuator at the predetermined opening angle. <EOS>