Soon, made-in-India mobile robots at Bajaj Auto plants

It may appear to be a regular shop in Pune, with the usual loading and unloading of raw materials. However, on taking a closer look, one finds there are no blue-collared workers on the floor. Instead, robots, more specifically, automated guided vehicles (AGVs), are busy transferring goods from one corner of the unit to the other.

These robots stop at a junction, receive the material on their powered-roller conveyors, swiftly move to the other junction and unload the material. On coming across an obstacle in their path, they stop immediately. Their path is pre-defined and guided through laser detectors. So, they do not lose track of their locations.
The unit is part of Bajaj Auto's manufacturing plant in Pune. This unit has been using AGVs for the last three-four years. The company always sought locally-made robots and had approached the Bhabha Atomic Research Centre (BARC)'s autonomous robotics division for such AGVs

“This is a first-generation robot. We want to explore it as much as possible. This AGV helps transfer material with precision and without delay, especially if several units in a manufacturing set-up fall on the same line,” says Prabir K Pal, head (autonomous robotics section), BARC. Jaldoot Material Handling Private, Pune, developed the motorised platform for the AGV, which was unveiled to the media a couple of weeks earlier. Bajaj Auto has offered the developer a site in Pune to test the machine on an experimental basis. These robots would start functioning in the unit in three-four months.

“Though the AGV imported from abroad had greater speed, Bajaj was paying more for it. So, we made a machine suited to their requirements, at less than half the original price,” says Pal. The AGV developed by BARC costs Rs 60 lakh, while the imported ones cost Rs 2 crore or more, depending on the extent to which the supply is customised and installed.

An AGV-based material transfer system has been developed for automated transfer of materials between the supply station, and the machining and assembly units of a manufacturing set-up. Automated loading and unloading are carried out by programmed motion of powered-roller conveyers on board the AGV and corresponding stationary units. Apart from the AGV's design and fabrication, the system includes various software modules for AGV motion control, position sensing (using laser navigator) and trajectory tracking.

The possible routes for the AGV, along with nominal speeds and stoppages, can be specified in advance, using a trajectory editor. This is a CAD-based software that helps import the layout drawing of the workshop. This facilitates specifying the routes and loading/unloading stations for the AGV. A supervisory control programme allows the operator to monitor the status of conveyors, and intervene if necessary. The user may explicitly issue commands for material transfer, and alternatively, the planning for the transfer of material from the supply station to machining units can be performed autonomously by an intelligent scheduler programme.

The AGV has a free-ranging technique for navigation. It detects cylindrical reflectors installed within the work area through an on-board laser-ranging device. It has two independently drivable and steerable wheels along its centre line and is supported by four caster wheels mounted at the corners. It can execute 'forward' and 'reverse' motions along straight lines, turn on an arc of specified radius, turn-in-place and crab. It has a capacity of about 700 kilograms and can attain a maximum speed of 1.5 metres per second in straight segments.

For safety purposes, the AGV has a set of bump sensors to be able to stop on contact. A laser scanner-based soft bumper installed in the AGV enables it to slow down or stop on encountering unexpected obstacles. The integrity of communication channels between various levels of the software is continuously monitored. If any breach of safety is detected, the AGV is stopped and the fault is indicated to the operator.
“Bajaj Auto has many plants. So, in principle, it can employ AGVs at many places. We were given detailed specifications for one such application, and we have worked towards developing a solution for that,” says Pal. BARC has also demonstrated this technology to potential users and manufacturers.

Hi-tech Robotic Systems, Gurgaon, also offers AGVs. But BARC officials feel in terms of capability, it is more limited. “Before this, at various stages, Electronics Corporation of India Limited (ECIL) and Bharat Heavy Electricals Limited have built AGVs of various capabilities. At the moment, our AGV is the most modern in terms of features,” claims Pal.

BARC officials say although a specific application in the automotive sector was picked up as a model to design the AGV and its control software, the solutions generated were general and could be used with modifications or enhancements in other application environments as well. “Since the control architecture is modular, a wide range of sensors, navigation and localisation systems can be interchangeably interfaced to the system, according to the availability and requirement,” says Pal.