ROS node using pyton ropspy package to send commands to topics in simple arm package to move the robotic joints.

simple_arm_arm.sh

import math
import rospy
from std_msgs.msg import Float64

def mover():
    pub_j1 = rospy.Publisher('/simple_arm/joint_1_position_controller/command',
                             Float64, queue_size=10)
    pub_j2 = rospy.Publisher('/simple_arm/joint_2_position_controller/command',
                             Float64, queue_size=10)
    rospy.init_node('arm_mover')
    rate = rospy.Rate(10)
    start_time = 0

    while not start_time:
        start_time = rospy.Time.now().to_sec()

    while not rospy.is_shutdown():
        elapsed = rospy.Time.now().to_sec() - start_time
        pub_j1.publish(math.sin(2*math.pi*0.1*elapsed)*(math.pi/2))
        pub_j2.publish(math.sin(2*math.pi*0.1*elapsed)*(math.pi/2))
        rate.sleep()

if __name__ == '__main__':
    try:
        mover()
    except rospy.ROSInterruptException:
        pass