Robotics nerd

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  1. 4 Bar Linkage Problem

    Anyone trying to solve a 4 bar linkage, can look at the file I have uploaded. It contains enough information and an external link to a PDF file that helped me in solving my 4 bar linkage. Solving 4 bar Linkage.pdf
  2. 4 Bar Linkage Problem

    Dear Drd, Thank you so much. I solved the problem by the following steps step-1 ) do vector loop analysis and get two equations(x and y) step-2) derive freudstein equation and simplify into 2 variables ( squaring and adding equations and removing 1 variable using trignometric identities) step-3) use half angle identities to get the desired joint angle as a quadratic equation whose coefficients depend on independent variable and link lenghts Your derivation is better! i will use both and see the results. Thank you again : ) Best Regards, Nerd
  3. 4 Bar Linkage Problem

    Dear DrD, Thank you for the response. I have gone through the posts in your blog. I can do the displacement analysis based on your methods by using vector loop equations and using the x and y parts separately to get two equations. The displacement methods assume that the given or known angle is the input crank angle. In my case, the motor is mounted at the joint joining the rocker and coupler. I can not measure the crank angle because it is a passive joint. What do you suggest for such a situation? Thank you.
  4. Hello guys, I am an electrical engineer, trying to solve a mechanical engineering problem. I am stuck at the analysis of the 4 bar cross quadrilateral linkage that allows a box as shown in figure 1 to pitch along z axis. Some information of symbols in figure -1 : -- The images are the top view with the z axis for each joint coming out of the paper. -- Joints (All joints are Revolute): J1 (Actuated by motor) J2 (Passive) J3 (Passive), J4 (Passive) -- Links: L34 is the ground link / fixed link L23 is the input link/ crank L12 is the coupler link L41 is the output link / rocker I have done alot of research over the past week and found freundstein equation. For solving it, it is assumed that the input crank angle is given but my motor is mounted at at joint J1. I have to find the pitch at joint J4 as a function of motor angle at Joint J1. Could some one please guide me in this matter.. The blue bot in the image is the motor axis of rotation( Joint J1). Link L12 is distance from the blue dot (joint J1) to the joint J2 and only link length L12 is important, you can ignore the link above the blue dot.. The housing of the motor as shown in figure below is fixed on the box and the I expect the whole box to pitch as shown in the following images about joint J4. After some rotation of the motor in clockwise direction, the box moves as shown below by rotating about joint J4.