Question

A robotic arm is controlled by several stepper motors.

Stepper motor (or step motor) is a brushless DC electric motor that divides a full rotation (360 degree) into a number of equal steps (10 degree/step in this case). The motor's position can then be commanded to move and hold at one of these steps without any feedback sensor (an open-loop controller). This motor usually has 4 wires. To move a motor, the following bit patterns should be applied to these 4 wires.

Clockwise rotation: 1100à0110à0011à1001 and these 4 patterns repeated again such as à1100à0110....

Counter clockwise rotation: 1100à1001à0011à0110à and these 4 patterns repeated again such as 1100à1001….

Each input pattern (for example 1100) moves motor 10 degree. Assume the first four bits (least Significant bits) of register R2 are connected to one these motors.

Write a program in LC-3 assembly language, to do the following:

If you type “1” motor moves 120 degree clockwise (sending 12 patterns) and then 90 degree counter clockwise (sending 9 patterns). If you type “2” motor moves 50 degree counter clockwise (sending 5 patterns).

Depends on what number you enter; the console should display all the related patterns sending to the motor.

Answer 1

A servomotor consumes energy because it rotates to the commanded function however then the servomotor rests. Stepper motors run warm to the contact due to the fact they proceed to consume vigour to lock in and preserve the commanded role.

Servomotors are typically used as a high performance replacement to the stepper motor. Stepper motors have some inherent potential to control role, as they have constructed-in output steps. This frequently allows for them to be used as an open-loop position control, with none feedback encoder, as their pressure signal specifies the number of steps of motion to rotate, however for this the controller wants to 'recognize' the function of the stepper motor on vigor up. Thus, on first vigor up, the controller will have got to set off the stepper motor and turn it to a known position, e.G. Except it activates an finish restrict swap. This will also be found when switching on an inkjet printer; the controller will move the ink jet service to the extreme left and correct to set up the end positions. A servomotor will immediately turn to something attitude the controller instructs it to, regardless of the preliminary function at vigor up.

The dearth of suggestions of a stepper motor limits its performance, as the stepper motor can most effective force a load that's well within its capacity, otherwise ignored steps below load could lead to positioning error and the approach may just ought to be restarted or recalibrated. The encoder and controller of a servomotor are another fee, but they optimise the performance of the total process (for all of velocity, vigour and accuracy) relative to the potential of the basic motor. With bigger methods, where a strong motor represents an increasing share of the procedure cost, servomotors have the knowledge.

There was growing fame in closed loop stepper motors in latest years. They act like servomotors but have some variations of their software manage to get smooth motion. The highest three manufacturers of closed loop stepper motor programs appoint magnetic encoders as their suggestions device of option because of low rate, and resistance to vibration. The important advantage of a closed loop stepper motor is the price to performance ratio. There's additionally no have got to tune the PID controller on a closed loop stepper system saving time.

Many applications, corresponding to laser cutting machines, may be provided in two tiers, the affordable variety making use of stepper motors and the excessive-performance range utilizing servomotors.