GB2486013A

GB2486013A - Omnidirectionally mobile robot having three feet

Info

Publication number: GB2486013A
Application number: GB1020382.6A
Authority: GB
Inventors: Gareth John Monkman; Daniel Wahler; Suraj Nandigahahlli Jayaprakash
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-12-02
Filing date: 2010-12-02
Publication date: 2012-06-06
Also published as: GB201020382D0

Abstract

This invention relates to a mobile robot comprising a minimal configuration of three controllable linear actuators 1 and three controllable feet 3. The device may be configured in a triangular or three armed star shape and may be driven omni-directionally. Movement of the robot is achieved by applying or releasing a brake (10 see fig 3b) to a ground engaging ball (8 see fig 3b) in each foot 3 and then extending or contracting selected linear actuators. The configuration of the robot overcomes accessibility issues experienced with circular robots used in cleaning. The invention is theoretically holonomic and experiences no kinematic singularities.

Description

Trilqpede rnc�jle robot

-Description

Many mobile service robots exist for cleaning purposes. Most suffer from an inability to reach into room corners because of their usually round design and a wheeled platform in which it is seldom possible to mount the wheels on the outer extremities of the device.

Legged mobile robots usually consist of pairs of legs with several joints (knee, ankle etc.). Less complicated designs are employed for snake like devices whereby the sliding of one or more members over a surface is required. For the latter a minimum of two linear actuators is required with a rotatable link between them. The greatest problem with this configuration is the mathematical singularity which occurs when both actuators are aligned along a common axis. The trilopede configuration overcomes this problem and also results in a robot capable of reaching into room corners.

Three linear actuators 1 may be connected together in delta (figure 1) or star (figure 2) form. The linear actuators I may comprise any mechanical prime mover capable of linear movement (for example: pneumatically, hydraulically, electrically etc. driven devices). As illustrated in figure 1 and 2, the ends of the said actuators 1 are connected together at a pivotal junction 2 where passive mechanical rotation orthogonal to the axis of linear actuation is allowed. At and underneath each of the three junctions 2 a foot 3 is mounted. The feet 3 are active in that they may be controlled in onloff states to achieve immobility (in the on state) of the said foot due to frictional resistance with respect to the surface 4 on which they reside or alternatively allow passive translation (in the off state) by means of free movement with minimal friction over the same surface 4.

Movement of the robot is achieved by selective control of the feet 3 and mechanical extension and contraction of the linear actuators 1 mounted physically between the junctions 2 above each of the three foot axes. For example adhesion with one foot 3 and movement of one or more actuators 1 will allow motion of the feet 3 which are not immobilised due to adhesion with the said surface 4.

Adhesion of the feet 3 may be achieved actively (for example: pneumatic suction, electroadhesion etc.) or passively (a high frictional coefficient between stationary foot and floor surface 4) at each linkS (which may be integrated with, or comprise part of; the junction 2).

In the configuration depicted in figure 1, each foot 3 (and any associated control mechanism) is connected to a pivotable junction 2 situated between the ends of two actuators 1.

In the configuration depicted in figure 2, each foot 3 (and any associated control mechanism) is connected to a pivotable junction 2 situated at one end of each actuators 1. The other end of the said actuator being secured to a central pivotable link similar to the link 2 but with or without an attached foot.

The foot may be a simple wheel and brake mechanism as depicted in figures 1 and 2. An alternative version of the feet 3 comprises a ball and collet arrangement as shown in figure 3. In the latter case, a frame 6 fitted with a collet 7 in order to retain a ball 8 or omnidirectional wheel as shown in figures 3a and 3b. The ball or wheel may be allowed to passively rotate by means of a bearing 9 and may be secured against rotation (immobilised) by means of a controllable mechanical brake mechanism 10. Thus, when the brake 10 is inactive, the free rotation of the ball 8 allows free movement of the foot 3 over the surface 4 in accordance with operation of the linear actuators 1.

Activating the brake 10 secures the ball 8 and prevents sliding movement of the foot 3 over the said surface 4.

Claims

Tn lppede mobile robot Claims 1. A mobile robot comprising three controllable linear actuators and three controllable feet connected together in star configuration by means of a common centre.
2. A mobile robot comprising three controllable linear actuators and three controllable feet connected together in delta configuration without a common centre.
3. A mobile robot as claimed in claim 1 and 2 comprising actuators which are mechanically binary (zero and full stroke states).
4. A mobile robot as claimed in claim 1 and 2 comprising actuators which have electromechanical proportional control capability.
5. A mobile robot as claimed in claims 1, 2, 3 and 4 equipped with feet whose adhesive action is mechanically binary (adhesive and non-adhesive states) intended to allow both states of mobility and immobility.
6. A mobile robot as claimed in claims 1, 2, 3 and 4 where the free movement of the said feet is possible in the non-adhesive (mobile) state.
7. A mobile robot as claimed in claims 1, 2, 3, 4, 5 and 6 where rotation of the foot joint around one axis may be allowed during the adhesive state.
8. A mobile robot as claimed in claims 1, 2, 3, 4, 5, 6 and 7 where the feet comprise wheels or balls or devices having other rotational geometries.