Hexapod Robots in Automotive Applications

Back to PI Website, www.pi-usa.usAs the precision requirements in the automotive industry are increasing, the need for advanced robotics arises. Traditional robots are fast, can handle heavy loads, but lack positioning accuracy. Hexapod robots have a long history in precision alignment & micro-manufacturing automation, but were considered too precise for the automotive industry. The situation is rapidly changing.

Best of two worlds: Combination of a traditional articulated-arm robot with a hexapod parallel-robot provides long travel ranges and very high precision and flexibility. (Image: PI)
Best of two worlds: Combination of a traditional articulated-arm robot with a hexapod parallel-robot provides long travel ranges and very high precision and flexibility. (Image: PI)

Modern hexapod controllers can communicate directly with a PLC or CNC controller via fieldbus interfaces, facilitating the integrating into the automation environment. Applications are found in quality assurance, test and metrology, prototype design and evaluation, and on the production line as a supplement to the traditional industrial robots or for the worker in partially automated processes.

Human-Robot Collaboration. The compact workspace of the hexapod is a benefit to worker safety when positioning parts in semi-automated manufacturing. (Image: PI)
Human-Robot Collaboration: The compact workspace of the hexapod is a benefit to worker safety when positioning parts in semi-automated manufacturing. (Image: PI)

Hexapods are not new to the automotive industry – on the contrary, one of the first industrial applications of parallel kinematic robots was tire testing under different angles, offsets, and loads.  The first machine was designed by Dr. Eric Gough, who was working for a tire manufacturer in Birmingham, England.

The first industrial hexapod was used in in a tire-testing machine (Image: PI)
The first industrial hexapod was used in in a tire-testing machine (Image: PI)
Custom Hexapod for automated precision metrology in the DM401 DYMACO Dimensional Measuring Machine (Image: Dymaco)
Custom Hexapod for automated precision metrology in the DM401 DYMACO Dimensional Measuring Machine (Image: Dymaco)

Today’s applications require much higher precision; first-tier automotive suppliers have discovered hexapods for coordinate measuring machines to calibrate headlamps and for the alignment of optical components that are becoming more and more mainstream for autonomous driving. Precision laser welding can also be improved with the help of hexapods.

Aligning, testing, and manufacturing. Hexapods have a long history for precision alignment and positioning applications. They also provide higher accuracy and repeatability than articulated robots, while requiring less space. Hexapods are installed in CMMs (coordinate measuring machines) to calibrate headlamps. Suppliers appreciate their use in prototype construction and for testing and processing complex components. Off-the-shelf hexapods can carry multi-ton loads while maintaining micrometer precision. (Image: PI)
Aligning, testing, and manufacturing: Hexapods have a long history for precision alignment and positioning applications. They also provide higher accuracy and repeatability than articulated robots, while requiring less space. Hexapods are installed in CMMs (coordinate measuring machines) to calibrate headlamps. Suppliers appreciate their use in prototype construction and for testing and processing complex components. Off-the-shelf hexapods can carry multi-ton loads while maintaining micrometer precision. (Image: PI)

Why Hexapods?

Basically it comes down to smaller size, higher stiffness, dynamics, precision, and greater flexibility – the user programmable pivot point allows rotations around any center in space and multiple coordinate systems (work piece and tool can be set in software). Additional advantages are the lack of dragging cables as common with classical, serial multi-axis positioning systems.

Hexapods on the production line: Hexapods are used in the automotive industry in conjunction with classical industrial robots. They increase the positioning repeatability and accuracy of the robotic system. For short travel ranges, they can replace the articulated-arm robot completely. (Image: PI)
Hexapods on the production line: Hexapods are used in the automotive industry in conjunction with classical industrial robots. They increase the positioning repeatability and accuracy of the robotic system. For short travel ranges, they can replace the articulated-arm robot completely. (Image: PI)

Control

The math behind the parallel coordinate transformation is completely transparent to the user, as all 6 degrees of freedom are commanded in Cartesian coordinates. PLC standard language can be used and the controller communicates with the hexapod via a standard protocol. In addition to TCP/IP and RS232, established fieldbus protocols, such as EtherCAT and PROFINET, are available. The hexapod system then behaves as an intelligent multi-axis drive on the bus.

The PLC controller communicates with the Hexapod via a standard protocol, such as EtherCAT. (Image: PI)
The PLC controller communicates with the Hexapod via a standard protocol, such as EtherCAT. (Image: PI)

Simulation Software

Simulation software and a virtual controller allow application development before the hardware is installed. A plethora of programming tools, such as drivers, VI’s, collision avoidance software and a mobile app for wireless monitoring, are available to simplify implementation.

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About PI

PI (Physik Instrumente) is a leading manufacturer of precision motion control equipment, piezo motors, air bearing stages and hexapod parallel-kinematics for semiconductor applications, photonics, bio-nano-technology and medical engineering. PI has been developing and manufacturing standard & custom precision products with piezoceramic and electromagnetic drives for 4 decades. The company has been ISO 9001 certified since 1994 and provides innovative, high-quality solutions for OEM and research. PI is present worldwide with fifteen subsidiaries, R&D / engineering on 3 continents and total staff of more than 1,000.

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