The importance of Robot Arms (Serial Manipulators) is increasing rapidly in the last few years in space, industrial and medical applications. An important part of Robot Arms is to achieve desired pose (position and orientation), in order to accomplish this very good knowledge of inverse kinematics is needed. Getting a solution to Inverse kinematics of the Robot Arms has been considered as a mature problem which is thoroughly researched and is also on the focus of various research and developments in Robotics field. SSRMS (a redundant manipulator) has total 7 revolute joints. They can be structured as shoulder joints, elbow joints and wrist joints (end effector). This paper presents biologically-inspired Genetic Algorithms (optimization) approach for solving Inverse kinematics problem of SSRMS. In this paper GA solver from MATLAB’s (optimization toolbox) is used to find the joint angles of SSRMS robot, solver parameters such as population size, elite count, crossover fraction, etc. are selected to achieve maximum performance resulting in optimum joint variables.

1. By
Satyendra Kumar Jaladi
Robotics & Mechatronics Engineering
Inverse Kinematics Analysis of Serial Manipulators
Using Genetic Algorithms
December 18th 2018

2. Contents

3. Aim & Objectives
• To provide Accurate,fast,efficient algorithm to
Inverse Kinematics(IK) of Serial Manipulators, As
DOF gets increased solving IK becomes more
complex(more than 1 solution).
• Solve IK of Serial Manipulators using Nature
Inspired optimization algorithms.
• Employ recently developed Optimization
Techniques for solving position level IK problems
of Robot Arms.

4. What is Kinematics

5. Robot Kinematics Terminology
Homogeneous Transformation Matrix (HTM)
0Tn = 0A1 * 1A2 * 2A3 .... n−1An
Forward Kinematics
ξN = Қ (qj)
Inverse Kinematics
qj = Қ-1 (ξN)
ξN = Pose of the Robot end effector.
qj = Vector of Robot joint angles.
j ϵ [1…. n].
DOF
N = 3 (r – 1) – 2p (Planar)
N = 6 (r – 1 ) – 5p (Spatial)
D-H Parameters
Joint angle θj
Revolute
joint variable
Link Offset dj
Prismatic
joint variable
Link Length aj constant
Link Twist αj constant
J-1TJ = trotz(theta_j) * transl(0,0,d_j) * transl(a_j,0,0) * trotx(alpha_j)

6. What is Genetic Algorithm? Why is it chosen?
• It’s a class of stochastic search
strategies modeled after evolutionary
mechanisms.
• Why use GA instead of Newton-
Raphson for minimization.
• Newton-Raphson( ̈𝑋𝑋) method is based
on the use of local information.
Genetic Algorithm
Minimize: min f(x1 x2 x3 xn)
𝒕𝒕𝒕𝒕𝒕𝒕𝒕𝒕𝒕𝒕, 𝐟𝐟𝐟𝐟𝐟𝐟𝐟𝐟, exitflag,output,population,scores = 𝒈𝒈𝒈𝒈(𝑭𝑭𝑭𝑭𝑭𝑭 𝑭𝑭𝑭𝑭𝑭𝑭𝑭𝑭_𝑭𝑭𝑭𝑭𝑭𝑭𝑭𝑭𝑭𝑭𝑭𝑭𝑭𝑭 𝑭𝑭, 𝒏𝒏𝒏𝒏𝒏𝒏𝒏𝒏𝒏𝒏, [], [], [], [], 𝑳𝑳𝑳𝑳, 𝑼𝑼𝑼𝑼, [], 𝒐𝒐𝒐𝒐𝒐𝒐𝒐𝒐);

7. Literature Survey
 By using a niching method, the algorithm is able to calculate multiple solutions of the IK
problem for both positioning and orienting the end-effector (Tabandeh, Saleh, Christopher M.
Clark, and William Melek)
 Some of the other well-known soft computing techniques which explored to solve the
Inverse kinematics are fuzzy logic, neural network, artificial neural network, ANFIS,
hybrid neural network etc. At the same time, much focus toward the use of the nature-
inspired algorithm for resolving the inverse kinematics problem of the industrial
manipulator as well as other problems related to the engineering field. The most commonly
used algorithms for solving the real-world problems are artificial bee colony(ABC). (Golak
Bihari Mahanta, B. B. V. L. Deepak, M. Dileep, B. B. Biswaland S. K. Pattanayak)

8. Methodology
• Min(GA) = FK+ Known Coordinates +TSP.
• Plugin Forward Kinematics equations.
• Feed the known Coordinates [Px , Py ,Pz]
(X1,Y1)
(X2,Y2)
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5
Euclidian Distance

9. Robotics Toolbox for MATLAB
• Visualization and Interpretation of results.
MATLAB's Robotics Toolbox Optimization Toolbox.

10. Fitness(Maximize/Minimize) Function
 Fitness function solves the FK equations and minimizes the
difference between the actual and desired pose resulting in
greater positioning accuracy.
2 2 2
1
( ) ( ) ( )
n
t x t y t z
j
x p y p z p
=
− + − + −∑Minimize
Subjected to angle bounds [LB,UB] θmin
θmax
Use 4-bit binary strings for range between [0 ≤ θ1 ,θ2 ≤ 90].
Accuracy =
XU – XL
(24 )– 1
=
𝟗𝟗𝟗𝟗 −𝟎𝟎
𝟏𝟏𝟏𝟏 −𝟏𝟏
= 60
Example of 2-DOF Robot ARM

11. Results
ABB (ASEA Brown Boveri)
Robot Type Handling
capacity(kg)
Reach(m)
IRB 1600 6kg 1.45m
P1 = [1.533;0.270;-0.4035];
P2 = [1.400;0.3512;-0.1089];
P3 = [-0.8502;1.1421;2.392];
ABB IRB 1600-6KG/1.45m Robot(6-DOF)
CAD model (MSC ADAMS)
Output Joint Angles [ degree ]0
θ1
19.01 29.00 9.00
θ2
19.21 19.21 19.21
θ3
20.22 34.04 32.0
θ4
20.01 20.01 20.01
θ5
29.99 9.01 59.01
θ6
59.01 59.01 59.01

12. References
1. Števo, Stanislav, Ivan Sekaj, and Martin Dekan. "Optimization of robotic arm trajectory using genetic algorithm." IFAC Proceedings Volumes 47, no. 3
(2014): 1748-1753.
2. Tabandeh, Saleh, William W. Melek, and Christopher M. Clark. "An adaptive niching genetic algorithm approach for generating multiple solutions of serial
manipulator inverse kinematics with applications to modular robots." Robotica 28, no. 4 (2010): 493-07.
3. Mahanta, Golak Bihari, B. B. V. L. Deepak, M. Dileep, B. B. Biswal, and S. K. Pattanayak. "Prediction of Inverse Kinematics for a 6-DOF Industrial Robot
Arm Using Soft Computing Techniques." In Soft Computing for Problem Solving, pp. 519-530. Springer, Singapore, 2019.
4. Corke, Peter I. "A robotics toolbox for MATLAB." IEEE Robotics & Automation Magazine 3, no. 1 (1996): 24-32.
5. Saha, S. K. (2014). Introduction to robotics. Tata McGraw-Hill Education .
6. Mittal, R. K., and I. J. Nagrath. Robotics and control. Tata McGraw-Hill, 2003.
7. Garg, D. P., & Kumar, M. (2002). Optimization techniques applied to multiple ma-nipulators for path planning and torque minimization. Engineering
Applications of Ar-tificial Intelligence, 15(3–4), 241–252.
8. Davidor, Y. (1991). Genetic Algorithms and Robotics, a Heuristic Strategy for Optimization. World Scientific Eiben, A.E., Smith, J.E. (2007). Introduction to
evolutionary computing. Springer.

13. THANK YOU.