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mimicJointConstraint.py creates actual differential drive

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See https://www.youtube.com/watch?v=pK3PTPlRTGA  :-)
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erwincoumans
2017-06-09 10:15:05 -07:00
parent 0aeb4d5058
commit b2a46a7edd
16 changed files with 219 additions and 8 deletions
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<?xml version="1.0" ?>
<robot name="husky_robot" xmlns:xacro="http://ros.org/wiki/xacro">
<material name="White">
<color rgba="1.0 1.0 1.0 1.0"/>
</material>
<link name="world"/>
<link name="diff_ring">
<contact>
<lateral_friction value="1.0"/>
<rolling_friction value="0.0"/>
<stiffness value="30000"/>
<damping value="1000"/>
</contact>
<inertial>
<mass value="2.637"/>
<origin xyz="0 0 0"/>
<inertia ixx="0.02467" ixy="0" ixz="0" iyy="0.02467" iyz="0" izz="0.04411"/>
</inertial>
<visual>
<origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
<geometry>
<mesh scale="0.001 0.001 0.001" filename="differential/diff_ring.stl"/>
</geometry>
<material name="DarkGrey"/>
</visual>
<visual>
<origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
<geometry>
<mesh scale="0.001 0.001 0.001" filename="differential/diff_carrier.stl"/>
</geometry>
<material name="DarkGrey"/>
</visual>
<collision>
<origin rpy="1.570795 0 0" xyz="0 0.025 0"/>
<geometry>
<cylinder length="0.01" radius="0.05"/>
</geometry>
</collision>
</link>
<joint name="diff_ring_world" type="continuous">
<parent link="world"/>
<child link="diff_ring"/>
<origin rpy="0 0 0" xyz="0.256 0.2854 0.03282"/>
<axis rpy="0 0 0" xyz="0 1 0"/>
</joint>
<link name="diff_spiderA">
<contact>
<lateral_friction value="1.0"/>
<rolling_friction value="0.0"/>
<stiffness value="30000"/>
<damping value="1000"/>
</contact>
<inertial>
<mass value="2.637"/>
<origin xyz="0 0 0"/>
<inertia ixx="0.02467" ixy="0" ixz="0" iyy="0.02467" iyz="0" izz="0.04411"/>
</inertial>
<visual>
<origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
<geometry>
<mesh scale="0.001 0.001 0.001" filename="differential/diff_spider.stl"/>
</geometry>
<material name="DarkGrey"/>
</visual>
<collision>
<origin rpy="1.570795 0 0" xyz="0 0.01 0"/>
<geometry>
<cylinder length="0.01" radius="0.015"/>
</geometry>
</collision>
</link>
<joint name="diff_spiderA_ring" type="continuous">
<parent link="diff_ring"/>
<child link="diff_spiderA"/>
<origin rpy="0 0 1.570795" xyz="0.0 0.0 0.0"/>
<axis rpy="0 0 0" xyz="0 1 0"/>
</joint>
<link name="diff_spiderB">
<contact>
<lateral_friction value="1.0"/>
<rolling_friction value="0.0"/>
<stiffness value="30000"/>
<damping value="1000"/>
</contact>
<inertial>
<mass value="2.637"/>
<origin xyz="0 0 0"/>
<inertia ixx="0.02467" ixy="0" ixz="0" iyy="0.02467" iyz="0" izz="0.04411"/>
</inertial>
<visual>
<origin rpy="1.57079632679 0 0" xyz="0 0 0"/>
<geometry>
<mesh scale="0.001 0.001 0.001" filename="differential/diff_spider.stl"/>
</geometry>
<material name="DarkGrey"/>
</visual>
<collision>
<origin rpy="1.570795 0 0" xyz="0 0.01 0"/>
<geometry>
<cylinder length="0.01" radius="0.015"/>
</geometry>
</collision>
</link>
<joint name="diff_spiderB_ring" type="continuous">
<parent link="diff_ring"/>
<child link="diff_spiderB"/>
<origin rpy="0 0 -1.570795" xyz="0.0 0.0 0.0"/>
<axis rpy="0 0 0" xyz="0 1 0"/>
</joint>
<link name="diff_sideA">
<contact>
<lateral_friction value="1.0"/>
<rolling_friction value="0.0"/>
<stiffness value="30000"/>
<damping value="1000"/>
</contact>
<inertial>
<mass value="2.637"/>
<origin xyz="0 0 0"/>
<inertia ixx="0.02467" ixy="0" ixz="0" iyy="0.02467" iyz="0" izz="0.04411"/>
</inertial>
<visual>
<origin rpy="1.570795 0 0" xyz="0 0 0"/>
<geometry>
<mesh scale="0.001 0.001 0.001" filename="differential/diff_side.stl"/>
</geometry>
<material name="DarkGrey"/>
</visual>
<collision>
<origin rpy="1.570795 0 0" xyz="0 0.01 0"/>
<geometry>
<cylinder length="0.01" radius="0.015"/>
</geometry>
</collision>
</link>
<joint name="diff_sideA_ring" type="continuous">
<parent link="diff_ring"/>
<child link="diff_sideA"/>
<origin rpy="0 0 0" xyz="0.0 0.0 0.0"/>
<axis rpy="0 0 0" xyz="0 1 0"/>
</joint>
<link name="diff_sideB">
<contact>
<lateral_friction value="1.0"/>
<rolling_friction value="0.0"/>
<stiffness value="30000"/>
<damping value="1000"/>
</contact>
<inertial>
<mass value="2.637"/>
<origin xyz="0 0 0"/>
<inertia ixx="0.02467" ixy="0" ixz="0" iyy="0.02467" iyz="0" izz="0.04411"/>
</inertial>
<visual>
<origin rpy="-1.570795 0 0" xyz="0 0 0"/>
<geometry>
<mesh scale="0.001 0.001 0.001" filename="differential/diff_side.stl"/>
</geometry>
<material name="DarkGrey"/>
</visual>
<collision>
<origin rpy="-1.570795 0 0" xyz="0 -0.01 0"/>
<geometry>
<cylinder length="0.01" radius="0.015"/>
</geometry>
</collision>
</link>
<joint name="diff_sideB_ring" type="continuous">
<parent link="diff_ring"/>
<child link="diff_sideB"/>
<origin rpy="0 0 0" xyz="0.0 0.0 0.0"/>
<axis rpy="0 0 0" xyz="0 1 0"/>
</joint>
</robot>

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stl files were copied from http://www.otvinta.com/download09.html
URDF file was manually created, along with mimicJointConstraint.py

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examples/Importers/ImportURDFDemo/UrdfParser.cpp
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@@ -323,8 +323,10 @@ bool UrdfParser::parseInertia(UrdfInertia& inertia, TiXmlElement* config, ErrorL
bool UrdfParser::parseGeometry(UrdfGeometry& geom, TiXmlElement* g, ErrorLogger* logger) bool UrdfParser::parseGeometry(UrdfGeometry& geom, TiXmlElement* g, ErrorLogger* logger)
{ {
btAssert(g); // btAssert(g);
if (g==0)
return false;
TiXmlElement *shape = g->FirstChildElement(); TiXmlElement *shape = g->FirstChildElement();
if (!shape) if (!shape)
{ {

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examples/pybullet/examples/mimicJointConstraint.py
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@@ -4,13 +4,22 @@
import pybullet as p import pybullet as p
import time import time
p.connect(p.GUI) p.connect(p.GUI)
wheelA = p.loadURDF("wheel.urdf",[0,0,0]) p.loadURDF("plane.urdf",0,0,-2)
wheelB = p.loadURDF("wheel.urdf",[0,0,1]) wheelA = p.loadURDF("differential/diff_ring.urdf",[0,0,0])
p.setJointMotorControl2(wheelA,0,p.VELOCITY_CONTROL,targetVelocity=0,force=0) for i in range(p.getNumJoints(wheelA)):
p.setJointMotorControl2(wheelB,0,p.VELOCITY_CONTROL,targetVelocity=1,force=1) print(p.getJointInfo(wheelA,i))
p.setJointMotorControl2(wheelA,i,p.VELOCITY_CONTROL,targetVelocity=0,force=0)
c = p.createConstraint(wheelA,1,wheelA,3,jointType=p.JOINT_GEAR,jointAxis =[0,1,0],parentFramePosition=[0,0,0],childFramePosition=[0,0,0])
p.changeConstraint(c,gearRatio=1, maxForce=10000)
c = p.createConstraint(wheelA,2,wheelA,4,jointType=p.JOINT_GEAR,jointAxis =[0,1,0],parentFramePosition=[0,0,0],childFramePosition=[0,0,0])
p.changeConstraint(c,gearRatio=-1, maxForce=10000)
c = p.createConstraint(wheelA,1,wheelA,4,jointType=p.JOINT_GEAR,jointAxis =[0,1,0],parentFramePosition=[0,0,0],childFramePosition=[0,0,0])
p.changeConstraint(c,gearRatio=-1, maxForce=10000)
c = p.createConstraint(wheelA,0,wheelB,0,jointType=p.JOINT_GEAR,jointAxis =[0,1,0],parentFramePosition=[0,0,0],childFramePosition=[0,0,0])
p.changeConstraint(c,gearRatio=-0.1, maxForce=10000)
p.setRealTimeSimulation(1) p.setRealTimeSimulation(1)
while(1): while(1):