com.yobotics.simulationconstructionset
Class PinJoint

java.lang.Object
  com.yobotics.simulationconstructionset.Joint
      com.yobotics.simulationconstructionset.PinJoint

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

CylinderJoint, GimbalJoint, UniversalJoint

public class PinJoint
extends Joint

Title: SimulationConstructionSet

Description: A rotational joint with a single degree of freedom. Pin joints allow rotation around a single axis specified upon creation. There are several joint types which extend this joint: universal, gimbal and cylinder joints. These joints are either multiple pin joints grouped together or a combination of pin and slider joints.

Copyright: Copyright (c) 2000

Company: Yobotics, Inc.

Version:

1.0

Author:

not attributable

See Also:

Joint, Serialized Form

Field Summary

Fields inherited from class com.yobotics.simulationconstructionset.Joint

MAX_ROT_ACCEL, MAX_TRANS_ACCEL, X, Y, Z

Constructor Summary

PinJoint(java.lang.String jname, javax.vecmath.Vector3d offset, Robot rob, int jaxis)
Creates a new pin joint and adds it to the specified robot.

PinJoint(java.lang.String jname, javax.vecmath.Vector3d offset, Robot rob, javax.vecmath.Vector3d u_hat)
Creates a new pin joint and adds it to the specified robot.

Method Summary

YoVariable	getQ() Retrieve the current angle (position) of this joint.
YoVariable	getQD() Retrieves the current velocity of this joint.
YoVariable	getQDD() Retrieves the current acceleration at this joint.
void	getState(double[] state) Inserts the given position and velocity of this pin joint into the provided array.
YoVariable	getTau() Retrieves the torque currently applied at this joint.
void	setDamping(double b_damp) Specifies the overall damping constant for this joint.
void	setInitialState(double q_init, double qd_init) Specify the intial position and velocity of this joint.
void	setLimitStops(double q_min, double q_max, double k_limit, double b_limit) Adds a set of limit stops to this joint.
void	setTau(double tau) Sets the torque applied to this joint.
void	setTorqueLimits(double tau_max) Sets a threshold for maximum allowed torque at this joint.
void	setVelocityLimits(double qd_max, double b_vel_limit) Adds a velocity limit for this joint.

Methods inherited from class com.yobotics.simulationconstructionset.Joint

addCameraMount, addExternalForcePoint, addGroundContactPoint, addJoint, addKinematicPoint, addRangeSensor, changeOffsetVector, changeOffsetVector, getChildrenJoints, getGroundContactPointGroup, getJointAxis, getLink, getName, getOffset, getRotationFromWorld, getRotationFromWorld, getTransformFromWorld, getTransformFromWorld, getTranslationFromWorld, getXYZFromWorld, getYawPitchRollFromWorld, isDynamic, recursiveDecideGroundContactPointsInContact, recursiveUpdateAllGroundContactPointVelocities, setDynamic, setLink, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

PinJoint

public PinJoint(java.lang.String jname,
                javax.vecmath.Vector3d offset,
                Robot rob,
                int jaxis)

Creates a new pin joint and adds it to the specified robot. There are three possible axis of rotation for this method: X, Y, and Z. To specified a particular axis use the public int provided in Joint.

Parameters:

jname - name of this joint

offset - Vector3d representing the offset from the robot origin to the joint.

rob - Robot to which this joint will belong

jaxis - int representing the axis

PinJoint

public PinJoint(java.lang.String jname,
                javax.vecmath.Vector3d offset,
                Robot rob,
                javax.vecmath.Vector3d u_hat)

Creates a new pin joint and adds it to the specified robot. This method allows the specification of an arbitrary joint axis.

Parameters:

jname - name of this joint

offset - Vector3d representing the offset from the robot origin to the joint.

rob - Robot to which this joint will belong

u_hat - Vector3d representing the axis of rotation

Method Detail

setInitialState

public void setInitialState(double q_init,
                            double qd_init)

Specify the intial position and velocity of this joint. This is used by gimbal, universal, and cylinder joints to initialize their member pin joints.

Parameters:

q_init - intial position of this joint in radians.

qd_init - intial velocity of this joint

getState

public void getState(double[] state)

Inserts the given position and velocity of this pin joint into the provided array. Index zero contains the position (angle) in radians, while index one contains the velocity.

Parameters:

state - double[]

setTau

public void setTau(double tau)

Sets the torque applied to this joint. Usually these variables are accessed by name instead of going through the joint.

Parameters:

tau - torque to be applied at this joint.

getQ

public YoVariable getQ()

Retrieve the current angle (position) of this joint.

Returns:

YoVariable representing the angle of this joint.

getQD

public YoVariable getQD()

Retrieves the current velocity of this joint.

Returns:

YoVariable representing the current angle of this joint.

getQDD

public YoVariable getQDD()

Retrieves the current acceleration at this joint.

Returns:

YoVariable representing the current acceleration

getTau

public YoVariable getTau()

Retrieves the torque currently applied at this joint.

Returns:

YoVariable representing the currently applied torque.

setLimitStops

public void setLimitStops(double q_min,
                          double q_max,
                          double k_limit,
                          double b_limit)

Adds a set of limit stops to this joint. This defines the allowed range of motion based on the provided min and max angles. Motion is constrained between these two values using a reaction torque calculated using the given spring and damper constants.

Parameters:

q_min - minimum allowed angle for this joint.

q_max - maximum allowed angle for this joint.

k_limit - spring constant used in torque calculations

b_limit - damping constant used in torque calculations

setVelocityLimits

public void setVelocityLimits(double qd_max,
                              double b_vel_limit)

Adds a velocity limit for this joint. This is achieved through the application of a resistive torque calculated based on the velocity and the provided damping fucntion.

Parameters:

qd_max - maximum allowed velocity

b_vel_limit - damping constant for torque calculations.

setTorqueLimits

public void setTorqueLimits(double tau_max)

Sets a threshold for maximum allowed torque at this joint. If a torque larger than the specified value is desired it will be cut to the given value.

Parameters:

tau_max - torque limit.

setDamping

public void setDamping(double b_damp)

Specifies the overall damping constant for this joint. If specified a torque base on this constant and the current velocity will be applied.

Parameters:

b_damp - general damping constant for this joint