tag:blogger.com,1999:blog-4183467386093942778.post6927553343123242839..comments2019-06-11T07:21:31.780-07:00Comments on aaronbot3000: Pythagoras: The Drawing Delta Robot: Math and Designaaronbot3000http://www.blogger.com/profile/03448341815321356647noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-4183467386093942778.post-25522905241181256992017-04-08T10:27:27.019-07:002017-04-08T10:27:27.019-07:00I hope to use stepper motor for the project then h...I hope to use stepper motor for the project then how I change the codes?Unknownhttps://www.blogger.com/profile/13948549354237417755noreply@blogger.comtag:blogger.com,1999:blog-4183467386093942778.post-47060596642378262362014-12-01T17:24:58.809-08:002014-12-01T17:24:58.809-08:00Aaron - You were pretty close on the fwd kinematic...Aaron - You were pretty close on the fwd kinematics. I think this will solve it exactly.<br /><br />I assume you are comfortable with vector addition in 3D.<br /><br />Let's work on solving the 3D point where motor1's downlinkage attaches to the end-effector. Call it LinkagePt1. You'll solve for LinkagePt2 and LinkagePt3 the same way, then solve for the end-effector centerpoint as the vector mean of these 3 Pts.<br /><br />We start by computing a 3D vector that goes from LinkagePt2 --> Linkage Pt1. Call it OffsetLinkage2_1. This is easy, since they are fixed points on the end-effector. You also need to compute OffsetLinkage3_1.<br /><br />The linkage arms are all length r. I assume you can compute cartesian coords {x y z ] for the linkage endpts of the 3 drivearms, based on the motor angles. Call these DriveArmTip1, DriveArmTip2, DriveArmTip3. You're intuition to use the intersection of 3 spheres is great.<br /><br />The accomodation you have to make is that, whatever sphere is carved out by the motor2's lower-linkage-tip (LinkagePt2), that sphere needs to be offset by vector OffsetLinkage2_1 when you go to intersect it with Sphere1. Why? because the point LinkagePt1 is the intersection of these 3 circles:<br /><br />LinkagePt1 = intersectionOf3Spheres (<br /> ( center = DriveArmTip1, radius = r ),<br /> (center DriveArmTip2 + OffsetLinkage2_1, radius = r ),<br /> (center DriveArmTip3 + OffsetLinkage3_1, radius = r ) )<br /><br />Same approach to compute LinkagePt2 and LinkagePt3.<br /><br />The end-effector center is then the vector mean<br /> (LinkagePt1 + LinkagePt2 + LinkagePt3 ) / 3<br /><br />pbierrehttps://www.blogger.com/profile/15764334913242128101noreply@blogger.com