US 12,611,771 B2 · TCP acceleration limitation for joint interpolated motions

Abstract

A method for computing robot motion where the tool center point translational acceleration does not exceed a defined limit. Robot motion for an upcoming segment of a trajectory is computed using a known “S-curve” technique, where joint motions are calculated which move the robot from a start pose to an end pose in the shortest time given maximum joint velocity, acceleration and jerk values. Significant points on the S-curve are identified which correspond with maximum translational acceleration of the tool center point. Tool center point Cartesian motion is then calculated from the joint motions using forward kinematics. The maximum translational acceleration of the tool center point is determined and compared to the defined acceleration limit. If the maximum acceleration of the tool center point exceeds the acceleration limit, the joint motions for the trajectory segment are re-calculated using a scale factor which reduces the joint and tool center point accelerations.

Claims20

Dependent claims

A method for tool center point acceleration limitation in a multi-axis robot, said method comprising:

computing, by a computing device, a robot joint motion profile for a trajectory, including computing joint motions for a time duration of the trajectory for all joints in the multi-axis robot;
calculating tool center point velocity and acceleration in Cartesian space for the time duration of the trajectory, based on the robot joint motion profile and robot geometry;
determining a maximum absolute value of tool center point acceleration during the trajectory;
and
when the maximum absolute value of tool center point acceleration exceeds a pre-defined tool center point acceleration limit, calculating a scale factor and re-computing the robot joint motion profile for the trajectory using a time constant which is increased by the scale factor;
and
when the maximum absolute value of tool center point acceleration does not exceed the tool center point acceleration limit, controlling the robot to move a tool center point through the trajectory.

4 more elements

A method for tool center point acceleration limitation in a multi-axis robot, said method comprising:

providing input parameters including robot joint mechanical constraints, start and end positions for a trajectory, and a tool center point acceleration limit;
computing, by a robot controller, a robot S-curve joint motion profile for the trajectory using the input parameters, including computing joint motions for a time duration of the trajectory for all joints in the multi-axis robot;
calculating tool center point velocity and acceleration in Cartesian space for the time duration of the trajectory, based on the S-curve joint motion profile and robot geometry;
determining a maximum absolute value of tool center point acceleration during the trajectory;
and
when the maximum absolute value of tool center point acceleration exceeds the tool center point acceleration limit, calculating a scale factor as a ratio of the maximum absolute value of tool center point acceleration to the tool center point acceleration limit, and re-computing the S-curve joint motion profile for the trajectory using a time constant which is increased by the scale factor, where the time constant is a time to reach an end of a maximum positive joint acceleration phase of the S-curve joint motion profile.

3 more elements

An industrial robot system with tool center point acceleration limitation, said system comprising:

a multi-axis robot;
and
a controller, having a processor and memory, in communication with the robot,
where the controller is configured with a tool center point acceleration limitation algorithm performing steps including;
computing a robot joint motion profile for a trajectory, including computing joint motions for a time duration of the trajectory for all joints in the multi-axis robot;
calculating tool center point velocity and acceleration in Cartesian space for the time duration of the trajectory, based on the robot joint motion profile and robot geometry;
determining a maximum absolute value of tool center point acceleration during the trajectory;
when the maximum absolute value of tool center point acceleration exceeds a pre-defined tool center point acceleration limit, calculating a scale factor and re-computing the robot joint motion profile for the trajectory using a time constant which is increased by the scale factor;
and
controlling the multi-axis robot to move a tool center point through the trajectory.

7 more elements

Dependencies are inferred from the claim text.

TCP acceleration limitation for joint interpolated motions

Life of this patent

TCP acceleration limitation for joint interpolated motions

Life of this patent

Abstract

Claims20