/*
 * Copyright (C) 2008  Manish Pandya, [manish at meetamanish dot com]
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 * 
 */
package org.hooliguns.ninja.telnet.phiPiMod;

/**
 * The backspace (Cntl-H for Halt) immediately stops all motion and exits from a
 * macro if one is running. All uninterpreted data in the serial port's FIFO
 * buffer is purged. Since the speed is not ramped down prior to a halt, rapid
 * motion may overshoot the internally-stored position by four steps. (See
 * "Motion Dynamics" below.) Otherwise, it remembers where it is, and an S or M
 * command can be used to resume travel to the next chosen position. Any defined
 * macro is preserved and may be restarted from the beginning with the R
 * command. It cannot be resumed where it left off.
 * <h4>Motion Dynamics</h4>
 * <p>
 * The stepper motors in the Ninja are run in open loop fashion. This is to say
 * that, other than in the centering operation (which uses position sensors),
 * the Ninja doesn't know where it is - just where it's supposed to be. Each
 * motor is operated with two coils always active at once while moving. (The
 * coils are turned off between moves.) The original Ninja program used just one
 * coil at a time. This gives the new configuration considerably more torque and
 * top-end speed than the old one. In order to accommodate the highest speeds,
 * the new program incorporates ramping. This allows the motors to accelerate
 * and decelerate smoothly, thus minimizing cogging (or step errors). Even with
 * ramping, though, the top error-free speed will vary, depending on the load
 * carried on the Ninja's platform. The higher the load, the lower the top speed
 * (or the more chance for position errors at high speed).
 * </p>
 * <p>
 * The Ninja is mechanically very sloppy. This is to say it has a lot of
 * backlash in its linkage from motor to platform. Backlash is most noticeable
 * when reversing direction. The motor has to rotate a little before actual
 * motion resumes. This is called taking up the backlash. The new program
 * incorporates backlash compensation. The amount of backlash present on each
 * axis has been characterized, and changes of direction are given that many
 * extra steps to compensate. These extra steps are incorporated into the entire
 * trajectory and will not normally be noticed. Although a better way is to
 * compensate the backlash before beginning the programmed trajectory, thus
 * making the trajectory itself correct from start to finish, the Ninja's
 * simpler way still allows the endpoints to be correct.
 * </p>
 * <p>
 * The Y (altitude) backlash cannot be entirely compensated out. The reason is
 * the platform's high center of gravity. With a moderate to heavy load, the Y
 * axis will appear to have no backlash - until it passes it's top equilibrium
 * point. There the load will cause the platform to "flop over the center" all
 * at once, then continue with no further backlash in evidence. The Y axis,
 * however, seems to be much tighter than the X axis, so this phenomenon is not
 * very pronounced.
 * </p>
 * 
 * @author Manish Pandya (July 1 2008)
 * 
 */
public class BackSpace extends CommandSingleChar {
	/**
	 * Creates a BackSpace command
	 */
	public BackSpace() {
		command = "\b";
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.hooliguns.ninja.telnet.Command#getHumanName()
	 */
	public String getHumanName() {
		return "BackSpace command";
	}
}